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  • 1.
    Amcoff, Mirjam
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Arnqvist, Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Courtship signalling with a labile bilateral signal: males show their best side2009Ingår i: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 63, nr 12, s. 1717-1725Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Asymmetries in courtship signals can result from both developmental instability during ontogeny and from temporary or permanent damage following mating, fighting, or interactions with predators. These two types of asymmetries, which can be divided into fluctuating asymmetry (FA) and damage asymmetry (DA), have both been suggested to play an important role in mate choice as potential honest indicators of phenotypic and/or genetic quality, while at the same time, DA may affect ornament asymmetry in a random manner. Interestingly, despite the massive research effort that has been devoted to the study of asymmetry during the past decades, very little is known about how an individual's behaviour relates to asymmetry. Here, we measure and characterise asymmetry in morphological courtship signals in Corynopoma riisei, a fish where males carry elaborate paddle-like appendices on each side of the body that they display in front of females during courtship. Moreover, we investigate whether male courtship display, employing this bilateral morphological trait, reflects trait asymmetry. Finally, we assess whether males respond to phenotypic manipulations of DA with corresponding changes in courtship behaviour. We show that male display behaviour is asymmetric in a manner that reflects asymmetry of their morphological courtship trait and that male display behaviour responds to manipulations of asymmetry of these paddles. Our results thus suggest that males preferentially use their best side and, hence, that males respond adaptively to temporary changes in signal trait asymmetry.

  • 2.
    Amcoff, Mirjam
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Gonzalez-Voyer, A.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Evolution of egg dummies in Tanganyikan cichlid fishes: the roles of parental care and sexual selection2013Ingår i: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 26, nr 11, s. 2369-2382Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Sexual selection has been suggested to be an important driver of speciation in cichlid fishes of the Great Lakes of Africa, and the presence of male egg dummies is proposed to have played a key role. Here, we investigate how mouthbrooding and egg dummies have evolved in Tanganyikan cichlids, the lineage which seeded the other African radiations, with a special emphasis on the egg dummies. Using modern phylogenetic comparative analyses and a phylogeny including 86% of the 200 described species, we provide formal evidence demonstrating correlated evolution between mouthbrooding and egg dummies in Tanganyikan cichlids. These results concur with existing evidence, suggesting that egg dummies have evolved through sensory exploitation. We also demonstrate that there is a strong evolutionary correlation between the presence of egg dummies and both pre- and post-copulatory sexual selection. Moreover, egg dummy evolution was contingent on the intensity of pre- and post-copulatory sexual selection in Tanganyikan cichlids. In sum, our results provide evidence supporting the hypothesis of egg dummies evolving through sensory exploitation and highlight the role of sexual selection in favouring the evolution and maintenance of this trait.

  • 3.
    Amcoff, Mirjam
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Hallsson, Lara R.
    Winberg, Svante
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för neurovetenskap, Fysiologi.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Male Courtship Pheromones Affect Female Behaviour in the Swordtail Characin ( Corynopoma riisei)2014Ingår i: Ethology, ISSN 0179-1613, E-ISSN 1439-0310, Vol. 120, nr 5, s. 463-470Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Pheromones constitute an important cue used by both males and females during courtship. Here, we investigate the effect of male pheromones on female behaviour in the swordtail characin (Corynopoma riisei), a species of fish where males have a caudal pheromone gland which has been suggested to affect female behaviour during courtship. We subjected female C.riisei to male courtship pheromones and investigated the effect on both female behaviour and brain serotonergic activity levels compared to a control group. While no difference in serotonergic activity was found, the pheromone-treated females showed lower stress levels compared to the control group. Furthermore, pheromone-treated females increased locomotor activity over time, while a decrease in locomotor activity was observed in the control group. These results suggest that the male courtship pheromones may serve to reduce female stress and increase female activity, possibly to aid males in gaining access to females and facilitating sperm transfer.

  • 4.
    Amcoff, Mirjam
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    A test of sensory exploitation in the swordtail characin (Corynopoma riisei) based on colour matchingbetween female prey and a male ornament2014Ingår i: Environmental Biology of Fishes, ISSN 0378-1909, E-ISSN 1573-5133, Vol. 97, nr 3, s. 247-254Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The sensory exploitation hypothesis states that pre-existing biases in female sensory systems may generate strong selection on male signals to match such biases. As environmental conditions differ between populations, sexual preferences resulting from natural selection are expected to vary as well. The swordtail characin (Corynopoma riisei) is a species in which males carry a flag-like ornament growing from the operculum that has been proposed to function as a prey mimic to attract females. Here, we investigated if female plasticity in feeding preferences is associated with plasticity in preference for an artificial male ornament in this species. Females were trained for 10 days by offering them differently coloured food items and were then tested for changes in preferences for differently coloured artificial male ornaments according to foraging experience. We found a rapid and pronounced change in female preference for the colouration of the artificial ornament according to food training. Thus our results support the possibility that sensory exploitation may act as a driving force for female preferences for male ornaments in this species.

  • 5.
    Amcoff, Mirjam
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Does female feeding motivation affect the response to a food-mimicking male ornament in the swordtail characin Corynopoma riisei?2013Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 83, nr 2, s. 343-354Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Female response to various aspects of male trait morphology and the effect of female feeding motivation were investigated in the swordtail characin Corynopoma riisei, a species where males are equipped with a flag-like food-mimicking ornament that grows from the operculum. Unfed females responded more strongly to the male ornament and showed a stronger preference for larger ornaments than did fed females. Females were shown not to discriminate between artificial male ornaments of either undamaged or damaged shape.

  • 6.
    Amcoff, Mirjam
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Kolm, Niclas
    Multiple male sexual signals and female responsiveness in the swordtail characin, Corynopoma riisei2015Ingår i: Environmental Biology of Fishes, ISSN 0378-1909, E-ISSN 1573-5133, Vol. 98, nr 7, s. 1731-1740Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the courtship process, multiple signals are often used between the signaller and the receiver. Here we describe female response to multiple male visual morphological and behavioural signals in the swordtail characin, Corynopoma riisei. The swordtail characin is a species in which males display several morphological ornaments as well as a rich courtship repertoire. Our results show that high courtship intensity was associated with an increased female response towards the male ornament, increased number of mating attempts and a reduction in female aggression. The morphological aspects investigated here did not seem to correlate with female response. This may indicate that, when both behaviour and morphology are considered simultaneously, courtship behaviour may have priority over morphological cues in this species.

  • 7.
    Amcoff, Mirjam
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Lindqvist, Charlotte
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Sensory exploitation and plasticity in female mate choice in the swordtail characin2013Ingår i: Animal Behaviour, ISSN 0003-3472, E-ISSN 1095-8282, Vol. 85, nr 5, s. 891-898Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Despite extensive research in the field of sexual selection, the evolutionary origin and maintenance of preferences for sexual ornaments are still debated. Recent studies have pointed out that plasticity in mate choice might be more common than previously thought, but little is still known about the factors that affect such plasticity. The swordtail characin, Corynopoma riisei, is a tropical fish species in which males use a food-mimicking ornament to attract females. We tested whether ecological factors, more specifically prior foraging experience, can affect female preference for male ornaments. For this, we habituated females on a diet consisting of either red-coloured food or standard-coloured green food items and then we tested whether female preferences for artificially red-coloured male ornaments matched their previous foraging experience. We found a strong effect of food treatment: females trained on red food showed a stronger response to males with red-coloured ornaments than females trained on green food. Our results show that ecological variation can generate divergence of female preferences for male ornaments and that the response in preference to environmental change can be rapid if the bias is partly learnt.

  • 8.
    Arnqvist, Göran
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Population differentiation in the swordtail characin (Corynopoma riisei): a role for sensory drive?2010Ingår i: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 23, nr 9, s. 1907-1918Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Sensory drive, where the efficacy of a sexual signal depends on the environment in which it is employed, is a potential mechanism behind divergent evolution of secondary sexual traits. Male swordtail characins are equipped with a narrow and transparent extension of the gill cover with a flag-like structure at its tip. This opercular flag mimics a prey item and is employed by males as a 'lure' to attract the attention of females during mating attempts. We conducted a study of genetic and morphological differentiation across swordtail characin populations throughout their native range in Trinidad. The morphology of the opercular flag varied across populations and several aspects of this variation match the predicted hallmarks of sensory drive. First, morphological differentiation of the flag across populations was unrelated to genetic similarity at neutral genetic markers. Second, the shape of the flag covaried with those aspects of body shape that should reflect adaptation to different feeding regimes. Third, and most importantly, the shape of the flag covaried across populations with those environmental characteristics that should most closely reflect differences in local prey abundance. Overall, our results are consistent with a scenario where the evolution of this male sexual signal tracks food-related shifts in female sensory biases across populations, thus providing at least provisional support for a role for sensory drive in population differentiation.

  • 9.
    Bloch, Natasha, I
    et al.
    UCL, Dept Genet Evolut & Environm, London, England.
    Corral-Lopez, Alberto
    Stockholm Univ, Dept Zool Ethol, Stockholm, Sweden.
    Buechel, Severine D.
    Stockholm Univ, Dept Zool Ethol, Stockholm, Sweden.
    Kotrschal, Alexander
    Stockholm Univ, Dept Zool Ethol, Stockholm, Sweden.
    Kolm, Niclas
    Stockholm Univ, Dept Zool Ethol, Stockholm, Sweden.
    Mank, Judith E.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för organismbiologi, Systematisk biologi. UCL, Dept Genet Evolut & Environm, London, England.
    Early neurogenomic response associated with variation in guppy female mate preference2018Ingår i: Nature Ecology & Evolution, E-ISSN 2397-334X, Vol. 2, nr 11, s. 1772-1781Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Understanding the evolution of mate choice requires dissecting the mechanisms of female preference, particularly how these differ among social contexts and preference phenotypes. Here, we studied the female neurogenomic response after only 10 min of mate exposure in both a sensory component (optic tectum) and a decision-making component (telencephalon) of the brain. By comparing the transcriptional response between females with and without preferences for colourful males, we identified unique neurogenomic elements associated with the female preference phenotype that are not present in females without preference. A network analysis revealed different properties for this response at the sensory-processing and the decision-making levels, and we show that this response is highly centralized in the telencephalon. Furthermore, we identified an additional set of genes that vary in expression across social contexts, beyond mate evaluation. We show that transcription factors among these loci are predicted to regulate the transcriptional response of the genes we found to be associated with female preference.

  • 10. Emerson, Brent C.
    et al.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Response to comments on Species diversity can drive speciation2007Ingår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 30, nr 3, s. 334-338Artikel i tidskrift (Refereegranskat)
  • 11. Emerson, Brent C.
    et al.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Species diversity can drive speciation: reply2007Ingår i: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 88, nr 8, s. 2135-2138Artikel i tidskrift (Refereegranskat)
  • 12. Fitzpatrick, J. L.
    et al.
    Almbro, M.
    Gonzalez-Voyer, A.
    Hamada, S.
    Pennington, C.
    Scanlan, J.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Sexual selection uncouples the evolution of brain and body size in pinnipeds2012Ingår i: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 25, nr 7, s. 1321-1330Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The size of the vertebrate brain is shaped by a variety of selective forces. Although larger brains (correcting for body size) are thought to confer fitness advantages, energetic limitations of this costly organ may lead to trade-offs, for example as recently suggested between sexual traits and neural tissue. Here, we examine the patterns of selection on male and female brain size in pinnipeds, a group where the strength of sexual selection differs markedly among species and between the sexes. Relative brain size was negatively associated with the intensity of sexual selection in males but not females. However, analyses of the rates of body and brain size evolution showed that this apparent trade-off between sexual selection and brain mass is driven by selection for increasing body mass rather than by an actual reduction in male brain size. Our results suggest that sexual selection has important effects on the allometric relationships of neural development.

  • 13. Fitzpatrick, J. L.
    et al.
    Almbro, M.
    Gonzalez-Voyer, A.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Simmons, L. W.
    Male Contest Competition And The Coevolution Of Weaponry And Testes In Pinnipeds2012Ingår i: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 66, nr 11, s. 3595-3604Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Male reproductive success is influenced by competitive interactions during precopulatory and postcopulatory selective episodes. Consequently, males can gain reproductive advantages during precopulatory contest competition by investing in weaponry and during postcopulatory sperm competition by investing in ejaculates. However, recent theory predicts male expenditure on weaponry and ejaculates should be subject to a trade-off, and should vary under increasing risk and intensity of sperm competition. Here, we provide the first comparative analysis of the prediction that expenditure on weaponry should be negatively associated with expenditure on testes mass. Specifically, we assess how sexual selection influences the evolution of primary and secondary sexual traits among pinnipeds (seals, sea lions, and walruses). Using recently developed comparative methods, we demonstrate that sexual selection promotes rapid divergence in body mass, sexual size dimorphism (SSD), and genital morphology. We then show that genital length appears to be positively associated with the strength of postcopulatory sexual selection. However, subsequent analyses reveal that both genital length and testes mass are negatively associated with investment in precopulatory weaponry. Thus, our results are congruent with recent theoretical predictions of contest-based sperm competition models. We discuss the possible role of trade-offs and allometry in influencing patterns of reproductive trait evolution in pinnipeds.

  • 14. Fitzpatrick, John L.
    et al.
    Montgomerie, Robert
    Desjardins, Julie K.
    Stiver, Kelly A.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Balshine, Sigal
    Female promiscuity promotes the evolution of faster sperm in cichlid fishes2009Ingår i: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 106, nr 4, s. 1128-1132Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Sperm competition, the contest among ejaculates from rival males to fertilize ova of a female, is a common and powerful evolutionary force influencing ejaculate traits. During competitive interactions between ejaculates, longer and faster spermatozoa are expected to have an edge; however, to date, there has been mixed support for this key prediction from sperm competition theory. Here, we use the spectacular radiation of cichlid fishes from Lake Tanganyika to examine sperm characteristics in 29 closely related species. We provide phylogenetically robust evidence that species experiencing greater levels of sperm competition have faster-swimming sperm. We also show that sperm competition selects for increases in the number, size, and longevity of spermatozoa in the ejaculate of a male, and, contrary to expectations from theory, we find no evidence of trade-offs among sperm traits in an interspecific analysis. Also, sperm swimming speed is positively correlated with sperm length among, but not within, species. These different responses to sperm competition at intra-and interspecific levels provide a simple, powerful explanation for equivocal results from previous studies. Using phylogenetic analyses, we also reconstructed the probable evolutionary route of trait evolution in this taxon, and show that, in response to increases in the magnitude of sperm competition, the evolution of sperm traits in this clade began with the evolution of faster (thus, more competitive) sperm.

  • 15.
    Gonzalez-Voyer, Alejandro
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Fitzpatrick, John L.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Evolutionsbiologi.
    Sexual selection determines parental care patterns in cichlid fishes2008Ingår i: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 62, nr 8, s. 2015-2026Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Despite a massive research effort, our understanding of why, in most vertebrates, males compete for mates and females care for offspring remains incomplete. Two alternative hypotheses have been proposed to explain the direction of causality between parental care and sexual selection. Traditionally, sexual selection has been explained as a consequence of relative parental investment, where the sex investing less will compete for the sex investing more. However, a more recent model suggests that parental care patterns result from sexual selection acting on one sex favoring mating competition and lower parental investment. Using species-level comparative analyses on Tanganyikan cichlid fishes we tested these alternative hypotheses employing a proxy of sexual selection based on mating system, sexual dichromatism, and dimorphism data. First, while controlling for female reproductive investment, we found that species with intense sexual selection were associated with female-only care whereas species with moderate sexual selection were associated with biparental care. Second, using contingency analyses, we found that, contrary to the traditional view, evolutionary changes in parental care type are dependent on the intensity of sexual selection. Hence, our results support the hypothesis that sexual selection determines parental care patterns in Tanganyikan cichlid fishes.

  • 16.
    Gonzalez-Voyer, Alejandro
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Rates of phenotypic evolution of ecological characters and sexual traits during the Tanganyikan cichlid adaptive radiation2011Ingår i: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 24, nr 11, s. 2378-2388Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Theory suggests that sexual traits evolve faster than ecological characters. However, characteristics of a species niche may also influence evolution of sexual traits. Hence, a pending question is whether ecological characters and sexual traits present similar tempo and mode of evolution during periods of rapid ecological divergence, such as adaptive radiation. Here, we use recently developed phylogenetic comparative methods to analyse the temporal dynamics of evolution for ecological and sexual traits in Tanganyikan cichlids. Our results indicate that whereas disparity in ecological characters was concentrated early in the radiation, disparity in sexual traits remained high throughout the radiation. Thus, closely related Tanganyikan cichlids presented higher disparity in sexual traits than ecological characters. Sexual traits were also under stronger selection than ecological characters. In sum, our results suggest that ecological characters and sexual traits present distinct evolutionary patterns, and that sexual traits can evolve faster than ecological characters, even during adaptive radiation.

  • 17.
    Gonzalez-Voyer, Alejandro
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Evolutionsbiologi.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Evolutionsbiologi.
    Sex, Ecology and the Brain: Evolutionary Correlates of Brain Structure Volumes in Tanganyikan Cichlids2010Ingår i: PLoS ONE, ISSN 1932-6203, Vol. 5, nr 12, s. e14355-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Analyses of the macroevolutionary correlates of brain structure volumes allow pinpointing of selective pressures influencing specific structures. Here we use a multiple regression framework, including phylogenetic information, to analyze brain structure evolution in 43 Tanganyikan cichlid species. We analyzed the effect of ecological and sexually selected traits for species averages, the effect of ecological traits for each sex separately and the influence of sexual selection on structure dimorphism. Our results indicate that both ecological and sexually selected traits have influenced brain structure evolution. The patterns observed in males and females generally followed those observed at the species level. Interestingly, our results suggest that strong sexual selection is associated with reduced structure volumes, since all correlations between sexually selected traits and structure volumes were negative and the only statistically significant association between sexual selection and structure dimorphism was also negative. Finally, we previously found that monoparental female care was associated with increased brain size. However, here cerebellum and hypothalamus volumes, after controlling for brain size, associated negatively with female-only care. Thus, in accord with the mosaic model of brain evolution, brain structure volumes may not respond proportionately to changes in brain size. Indeed selection favoring larger brains can simultaneously lead to a reduction in relative structure volumes.

  • 18.
    Gonzalez-Voyer, Alejandro
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Winberg, Svante
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för neurovetenskap, Fysiologi.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Brain structure evolution in a basal vertebrate clade: evidence from phylogenetic comparative analysis of cichlid fishes2009Ingår i: BMC Evolutionary Biology, ISSN 1471-2148, E-ISSN 1471-2148, Vol. 9, s. 238-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

     Background: The vertebrate brain is composed of several interconnected, functionally distinct structures and much debate has surrounded the basic question of how these structures evolve. On the one hand, according to the 'mosaic evolution hypothesis', because of the elevated metabolic cost of brain tissue, selection is expected to target specific structures mediating the cognitive abilities which are being favored. On the other hand, the 'concerted evolution hypothesis' argues that developmental constraints limit such mosaic evolution and instead the size of the entire brain varies in response to selection on any of its constituent parts. To date, analyses of these hypotheses of brain evolution have been limited to mammals and birds; excluding Actinopterygii, the basal and most diverse class of vertebrates. Using a combination of recently developed phylogenetic multivariate allometry analyses and comparative methods that can identify distinct rates of evolution, even in highly correlated traits, we studied brain structure evolution in a highly variable clade of ray-finned fishes; the Tanganyikan cichlids.

    Results: Total brain size explained 86% of the variance in brain structure volume in cichlids, a lower proportion than what has previously been reported for mammals. Brain structures showed variation in pair-wise allometry suggesting some degree of independence in evolutionary changes in size. This result is supported by variation among structures on the strength of their loadings on the principal size axis of the allometric analysis. The rate of evolution analyses generally supported the results of the multivariate allometry analyses, showing variation among several structures in their evolutionary patterns. The olfactory bulbs and hypothalamus were found to evolve faster than other structures while the dorsal medulla presented the slowest evolutionary rate.

    Conclusion: Our results favor a mosaic model of brain evolution, as certain structures are evolving in a modular fashion, with a small but non-negligible influence of concerted evolution in cichlid fishes. Interestingly, one of the structures presenting distinct evolutionary patterns within cichlids, the olfactory bulbs, has also been shown to evolve differently from other structures in mammals. Hence, our results for a basal vertebrate clade also point towards a conserved developmental plan for all vertebrates.

  • 19.
    Gonzalez-Voyer, Alejandro
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Winberg, Svante
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för neurovetenskap, Fysiologi.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Distinct Evolutionary Patterns of Brain and Body Size During Adaptive Radiation2009Ingår i: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 63, nr 9, s. 2266-2274Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Morphological traits are often genetically and/or phenotypically correlated with each other and such covariation can have an important influence on the evolution of individual traits. The strong positive relationship between brain size and body size in vertebrates has attracted a lot of interest, and much debate has surrounded the study of the factors responsible for the allometric relationship between these two traits. Here, we use comparative analyses of the Tanganyikan cichlid adaptive radiation to investigate the patterns of evolution for brain size and body size separately. We found that body size exhibited recent bursts of rapid evolution, a pattern that is consistent with divergence linked to ecological specialization. Brain weight on the other hand, showed no bursts of divergence but rather evolved in a gradual manner. Our results thus show that even highly genetically correlated traits can present markedly different patterns of evolution, hence interpreting patterns of evolution of traits from correlations in extant taxa can be misleading. Furthermore, our results suggest, contrary to expectations from theory, that brain size does not play a key role during adaptive radiation.

  • 20.
    Gonzalez-Voyer, Alejandro
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Winberg, Svante
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för neurovetenskap, Fysiologi.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Social fishes and single mothers: brain evolution in African cichlids2009Ingår i: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 276, nr 1654, s. 161-167Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    As with any organ, differences in brain size-after adequate control of allometry-are assumed to be a response to selection. With over 200 species and an astonishing diversity in niche preferences and social organization, Tanganyikan cichlids present an excellent opportunity to study brain evolution. We used phylogenetic comparative analyses of sexed adults from 39 Tanganyikan cichlid species in a multiple regression framework to investigate the influence of ecology, sexual selection and parental care patterns on whole brain size, as well as to analyse sex-specific effects. First, using species-specific measures, we analysed the influence of diet, habitat, form of care (mouthbrooding or substrate guarding), care type (biparental or female only) and intensity of sexual selection on brain size, while controlling for body size. Then, we repeated the analyses for male and female brain size separately. Type of diet and care type were significantly correlated with whole brain size. Sex-specific analyses showed that female brain size correlated significantly with care type while male brain size was uncorrelated with care type. Our results suggest that more complex social interactions associated with diet select for larger brains and further that the burden of uniparental care exerts high cognitive demands on females.

  • 21. Hoffman, Eric A.
    et al.
    Arquello, J. Roman
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Jones, Adam G.
    Eleven polymorphic microsatellite loci in a coral reef fish, Pterapogon kauderni2004Ingår i: Molecular Ecology Notes, ISSN 1471-8278, E-ISSN 1471-8286, Vol. 4, nr 3, s. 342-344Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We describe the isolation and characterization of 11 polymorphic tetranucleotide microsatellite loci from a male mouthbrooding coral reef fish, the Banggai cardinalfish Pterapogon kauderni. In a sample of 37 fish from a natural population, polymorphism at these loci ranged from two to 15 alleles, with expected heterozygosities ranging from 0.107 to 0.928, enabling high-resolution genetic studies of this coral reef fish.

  • 22. Hoffman, Eric A.
    et al.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Arquello, J. Roman
    Jones, A dam G.
    Genetic structure in the coral-reef-associated Banggai cardinalfish, Pterapogon kauderni2005Ingår i: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 14, nr 5, s. 1367-1375Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, we used 11 polymorphic microsatellite loci to show that oceanic distances as small as 2–5 km are sufficient to produce high levels of population genetic structure (multilocus FST as high as 0.22) in the Banggai cardinalfish(Pterapogon kauderni), a heavily exploited reef fish lacking a pelagic larval dispersal phase. Global FST among all populations, separated by a maximum distance of 203 km, was 0.18 (RST = 0.35). Moreover, two lines of evidence suggest that estimates of FST may actually underestimate the true level of genetic structure. First, within-locus FST values were consistently close to the theoretical maximum set by the average within-population heterozygosity. Second, the allele size permutation test showed that RST values were significantly larger than FST values, indicating that populations have been isolated long enough for mutation to have played a role in generating allelic variation among populations. The high level of microspatial structure observed in this marine fish indicates that life history traits such as lack of pelagic larval phase and a good homing ability do indeed play a role in shaping population genetic structure in the marine realm.

  • 23.
    Höglund, Erik
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för evolutionsbiologi, Limnologi.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för evolutionsbiologi, Zooekologi.
    Winberg, Svante
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för fysiologi och utvecklingsbiologi, Jämförande fysiologi. Jämförande fysiologi.
    Stress-induced changes in brain serotonergic activity, plasma cortisol and aggressive behavior in Arctic charr (Salvelinus alpinus) is counteracted by L-DOPA2001Ingår i: Physiology and Behavior, ISSN 0031-9384, E-ISSN 1873-507X, Vol. 74, nr 3, s. 381-389Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Arctic charr (Salvelinus alpinus) were tested for aggressive behavior using intruder tests, before and after 2 days of dyadic social interaction. Following social interaction, half of the dominant and half of the subordinate fish were given l-DOPA (10 mg/kg, orally), whereas the remaining dominant and subordinate fish were given vehicle. One hour following drug treatment, the fish were tested for aggressive behavior again in a third and final intruder test, after which blood plasma and brain tissue were sampled for analysis of plasma cortisol concentrations and brain levels of monoamines and monoamine metabolites. Subordinate fish showed a reduction in the number of attacks launched against the intruder, as well as an increase in attack latency, as compared to prior to dyadic social interactions. Social subordination also resulted in an elevation of brain serotonergic activity. Fish receiving l-DOPA prior to the final intruder test showed shorter attack latency than vehicle controls. Drug treatment was a stressful experience and vehicle controls showed elevated plasma cortisol levels and longer attack latency as compared to before treatment. l-DOPA-treated fish showed lower plasma levels of cortisol and lower serotonergic activity in certain brain areas than vehicle controls. These results suggest that l-DOPA counteracts the stress-induced inhibition of aggressive behavior, and at the same time inhibits stress-induced effects on brain serotonergic activity and plasma cortisol concentrations.

  • 24.
    Kolm, N
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Teknisk-naturvetenskapliga fakulteten, Biologiska sektionen, Institutionen för ekologi och evolution. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Teknisk-naturvetenskapliga fakulteten, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi. Zooekologi.
    Goodwin, NB
    Balshine, S
    Reynolds, JD
    Life history evolution in cichlids 1: Revisiting the evolution of life histories in relation to parental care2006Ingår i: Journal of Evolutionary Biology, Vol. 19, s. 66-75Artikel i tidskrift (Refereegranskat)
  • 25.
    Kolm, N
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Teknisk-naturvetenskapliga fakulteten, Biologiska sektionen, Institutionen för ekologi och evolution. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Teknisk-naturvetenskapliga fakulteten, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi. Zooekologi.
    Goodwin, NB
    Balshine, S
    Reynolds, JD
    Life history evolution in cichlids 2: directional evolution of the trade-off between egg number and egg size2006Ingår i: Journal of Evolutionary Biology, Vol. 19, s. 76-84Artikel i tidskrift (Refereegranskat)
  • 26.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Female courtship in the Banggai cardinalfish: honest signals of egg maturity and reproductive output?2004Ingår i: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 56, nr 1, s. 59-64Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Despite the vast literature on male courtship behaviour, little is known about the function and information content of female courtship behaviour. Female courtship behaviour may be important in many species, particularly where both sexes invest heavily in the offspring, and if such behaviours contain honest information regarding a female’s potential reproductive investment, they may be particularly important in male mate choice. Using observations of two female courtship behaviours (the “rush” and the “twitch”) from experimental pairings in the Banggai cardinalfish (Pterapogon kauderni), I addressed the question of whether these courtship behaviours contained information on female reproductive output (clutch weight) and egg maturity (proximity to spawning), traits commonly associated with male mate choice. I especially focused on the importance of these courtship behaviours in relation to other female characters, such as size and condition, using multiple regression. I found that one of these behaviours, the rush, was strongly associated with fecundity, whereas size, condition and the twitch were not. Further, I found that the “twitch” behaviour was associated with how close to actual spawning a female was. The results suggest that female courtship behaviour may convey highly important information in a mate choice context. I discuss the adaptive value of honest information in female courtship behaviour in light of these results.

  • 27.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för evolutionsbiologi, Zooekologi.
    Females produce larger eggs for large males in a paternal mouthbrooding fish2001Ingår i: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 268, nr 1482, s. 2229-2234Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    When individuals receive different returns from their reproductive investment dependent on mate quality, they are expected to invest more when breeding with higher quality mates. A number of studies over the past decade have shown that females may alter their reproductive effort depending on the quality/attractiveness of their mate. However, to date, despite extensive work on parental investment, such a differential allocation has not been demonstrated in fish. Indeed, so far only two studies from any taxon have suggested that females alter the quality of individual offspring according to the quality/attractiveness of their mate. The banggai cardinal fish is an obligate paternal mouth brooder where females lay few large eggs. It has previously been shown that male size determines clutch weight irrespective of female size in this species. In this study, I investigated whether females perform more courtship displays towards larger males and whether females allocate their reproductive effort depending on the size of their mate by experimentally assigning females to either large or small males. I found that females displayed more towards larger males, thereby suggesting a female preference for larger males. Further, females produced heavier eggs and heavier clutches but not more eggs when paired with large males. My experiments show that females in this species adjust their offspring weight and, thus, presumably offspring quality according to the size of their mate.

  • 28.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för evolutionsbiologi, Zooekologi.
    Influence of Mate Quality on Reproductive Decisions in a Fish with Paternal Care2003Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Female reproductive decisions have been suggested to be highly influenced by mate quality. I have studied whether offspring quality may be adjusted by females to match the attractiveness of males and how strong control females have over their reproductive investment focusing on egg size. This was done in the Banggai cardinalfish (Pterapogon kauderni), a sex-role reversed obligate paternal mouthbrooder where males invest heavily into reproduction. As this species is suitable for both laboratory experiments and field studies it is an ideal candidate for the study of reproductive investment.

    Mating was size-assortative and both males and females benefited from pairing with large partners. However, male size determined the reproductive output of a pair. Females courted large males more intensively and produced larger, but not fewer eggs when mated to large males as compared to small males. Further, this matching of egg size to mate attractiveness may be fast. Female courtship behaviours contained honest information regarding both clutch weight and egg maturity, traits that may be highly important for male mate choice. Surprisingly, males played an important part in territory defence suggesting relatively equal sex-roles in this species. Also, this species showed stable group structures which may be important for the evolution of female plasticity in reproductive investment due to high variance in quality of available mates.

    This thesis suggest that females have a remarkable control over their reproductive investments and that male quality may be highly influential on reproductive decisions regarding offspring quality. Furthermore, it suggest that sexual selection may have strong effects on the evolution of egg size and parental care on a whole.

    Delarbeten
    1. Male size determines reproductive output in a paternal mouthbrooding fish
    Öppna denna publikation i ny flik eller fönster >>Male size determines reproductive output in a paternal mouthbrooding fish
    2002 (Engelska)Ingår i: Animal Behaviour, ISSN 0003-3472, E-ISSN 1095-8282, Vol. 63, nr 4, s. 727-733Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Size can have strong effects on reproductive success in both males and females, and in many species large individuals are preferred as mates. To estimate the potential benefits from mate choice for size in both sexes, I studied the effects of the size of each sex on the reproductive output of pairs of Banggai cardinalfish, Pterapogon kauderni, a sexually monomorphic obligate paternal mouthbrooder. When pairs were allowed to form freely, a size-assortative mating pattern was observed and larger pairs had a higher reproductive output as determined by total clutch weight and egg size. To separate the potential benefits from mate choice for size for each sex, I subsequently used these pairs to form reversed size-assortative pairs, that is, the largest male paired to the smallest female and vice versa. I found a positive correlation between male size and clutch size: relatively heavier clutches were found in pairs where females were given a larger male. This suggests that the size of the male influences clutch weight. For egg size, however, the size of both sexes seemed important. The study reveals the benefits of mutual mate choice on size in this species: larger females provide larger eggs and larger males can brood heavier clutches. Furthermore, these results suggest that females differentially allocate resources into the eggs according to the size of the mate.

    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:uu:diva-90785 (URN)10.1006/anbe.2001.1959 (DOI)
    Tillgänglig från: 2003-09-04 Skapad: 2003-09-04 Senast uppdaterad: 2017-12-14Bibliografiskt granskad
    2. Females produce larger eggs for large males in a paternal mouthbrooding fish
    Öppna denna publikation i ny flik eller fönster >>Females produce larger eggs for large males in a paternal mouthbrooding fish
    2001 (Engelska)Ingår i: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 268, nr 1482, s. 2229-2234Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    When individuals receive different returns from their reproductive investment dependent on mate quality, they are expected to invest more when breeding with higher quality mates. A number of studies over the past decade have shown that females may alter their reproductive effort depending on the quality/attractiveness of their mate. However, to date, despite extensive work on parental investment, such a differential allocation has not been demonstrated in fish. Indeed, so far only two studies from any taxon have suggested that females alter the quality of individual offspring according to the quality/attractiveness of their mate. The banggai cardinal fish is an obligate paternal mouth brooder where females lay few large eggs. It has previously been shown that male size determines clutch weight irrespective of female size in this species. In this study, I investigated whether females perform more courtship displays towards larger males and whether females allocate their reproductive effort depending on the size of their mate by experimentally assigning females to either large or small males. I found that females displayed more towards larger males, thereby suggesting a female preference for larger males. Further, females produced heavier eggs and heavier clutches but not more eggs when paired with large males. My experiments show that females in this species adjust their offspring weight and, thus, presumably offspring quality according to the size of their mate.

    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:uu:diva-90786 (URN)10.1098/rspb.2001.1792 (DOI)
    Tillgänglig från: 2003-09-04 Skapad: 2003-09-04 Senast uppdaterad: 2017-12-14Bibliografiskt granskad
    3. Differential investment in the Banggai cardinalfish: can females adjust egg size close to egg maturation to match the attractiveness of a new partner?
    Öppna denna publikation i ny flik eller fönster >>Differential investment in the Banggai cardinalfish: can females adjust egg size close to egg maturation to match the attractiveness of a new partner?
    2003 (Engelska)Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 63, nr S1, s. 144-151Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    To test whether females can change their egg investment according to the different attractiveness ( i.e. size as measured by standard length, Ls) of a new mate after eggs have already matured in response to an earlier mate, female Banggai cardinalfish Pterapogon kauderni were first allowed to produce eggs for small (unattractive) or large (attractive) males. Then, when spawning was initiated, but prior to actual spawning, their partner was switched to either a significantly larger or a significantly smaller partner, respectively. A strong positive correlation between egg size and days until spawning with the second male was found for the females initially paired to a small and then a large male. Within a few days, these females apparently increased their egg size to match the attractiveness of their new male. No correlation between days until spawning and egg size in females initially paired to a large and then a small male, however was found, so apparently females were unable to adjust egg size in response to a decrease in mate attractiveness. Consequently, it is suggested that females can increase their egg size investment even after the onset of egg maturation and that this change can be quite rapid.

    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:uu:diva-90787 (URN)10.1111/j.1095-8649.2003.00205.x (DOI)
    Tillgänglig från: 2003-09-04 Skapad: 2003-09-04 Senast uppdaterad: 2017-12-14Bibliografiskt granskad
    4. Female courtship in the Banggai cardinalfish: honest signals of egg maturity and reproductive output?
    Öppna denna publikation i ny flik eller fönster >>Female courtship in the Banggai cardinalfish: honest signals of egg maturity and reproductive output?
    2004 (Engelska)Ingår i: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 56, nr 1, s. 59-64Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Despite the vast literature on male courtship behaviour, little is known about the function and information content of female courtship behaviour. Female courtship behaviour may be important in many species, particularly where both sexes invest heavily in the offspring, and if such behaviours contain honest information regarding a female’s potential reproductive investment, they may be particularly important in male mate choice. Using observations of two female courtship behaviours (the “rush” and the “twitch”) from experimental pairings in the Banggai cardinalfish (Pterapogon kauderni), I addressed the question of whether these courtship behaviours contained information on female reproductive output (clutch weight) and egg maturity (proximity to spawning), traits commonly associated with male mate choice. I especially focused on the importance of these courtship behaviours in relation to other female characters, such as size and condition, using multiple regression. I found that one of these behaviours, the rush, was strongly associated with fecundity, whereas size, condition and the twitch were not. Further, I found that the “twitch” behaviour was associated with how close to actual spawning a female was. The results suggest that female courtship behaviour may convey highly important information in a mate choice context. I discuss the adaptive value of honest information in female courtship behaviour in light of these results.

    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:uu:diva-90788 (URN)10.1007/s00265-003-0754-5 (DOI)
    Tillgänglig från: 2003-09-04 Skapad: 2003-09-04 Senast uppdaterad: 2017-12-14Bibliografiskt granskad
    5. Sex-specific territorial behaviour in the Banggai cardinalfish, Pterapogon kauderni
    Öppna denna publikation i ny flik eller fönster >>Sex-specific territorial behaviour in the Banggai cardinalfish, Pterapogon kauderni
    2004 (Engelska)Ingår i: Environmental Biology of Fishes, ISSN 0378-1909, E-ISSN 1573-5133, Vol. 70, nr 4, s. 375-379Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    In a field experiment, we studied how levels of aggression in males and females in established pairs of the Banggai cardinalfish were influenced by the sex of an experimentally introduced individual larger and more attractive than its resident counterpart. Contrary to previous studies on other cardinalfish species, and contrary to expectations in a sex role reversed species, the male was the main aggressor towards an intruder. Moreover, residents were more aggressive towards an intruder of the same sex as themselves. Furthermore, even though females often courted introduced, larger males, no intruder managed to take over the partnership of any resident. We suggest that our findings imply relatively equal sex roles in the Banggai cardinalfish and we discuss the evolution of sex specific territory defence and its significance in the Banggai cardinalfish as well as the implications of such behaviour in the interpretations of sex roles in general.

    Nyckelord
    territorial defence, sex, sex roles
    Nationell ämneskategori
    Biologiska vetenskaper
    Identifikatorer
    urn:nbn:se:uu:diva-90789 (URN)10.1023/B:EBFI.0000035430.76766.53 (DOI)000222800800009 ()
    Tillgänglig från: 2003-09-04 Skapad: 2003-09-04 Senast uppdaterad: 2017-12-14Bibliografiskt granskad
    6. Wild Populations of a Reef Fish Suffer from the “Nondestructive” Aquarium Trade Fishery
    Öppna denna publikation i ny flik eller fönster >>Wild Populations of a Reef Fish Suffer from the “Nondestructive” Aquarium Trade Fishery
    2003 (Engelska)Ingår i: Conservation Biology, ISSN 0888-8892, E-ISSN 1523-1739, Vol. 17, nr 3, s. 910-914Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    The commercial fishery for coral reef fish for the aquarium trade has begun to change, at least in some parts of the world, from destructive methods such as cyanide and dynamite fishing to less-destructive methods such as hand-net fishing. However, data on the effects on wild populations of such relatively nondestructive methods is nonexistent. The Banggai cardinalfish (   Pterapogon kauderni ) is a paternal mouthbrooder living in groups of 2–200 individuals in the proximity of sea urchins (   Diadema setosum ). This fish has limited dispersal abilities because it lacks a pelagic larval phase, and it is believed to be endemic to the Banggai archipelago off the east coast of Sulawesi, Indonesia. Since its rediscovery in 1995, the Banggai cardinalfish has become a popular aquarium fish, and thousands have been exported—mainly to North America, Japan, and Europe. To study the effects of the aquarium trade fishery on wild populations of the Banggai cardinalfish, we performed a field study in which we quantified density, age distribution ( quantified as the ratio of numbers of juveniles to adults ) and habitat quality ( i.e., sea urchin density ) at eight sites in the Banggai archipelago. Through interviews with local fishers, we estimated the fishing pressure at each site and related this to data on fish density. We found a marginally significant negative effect of fishing pressure on density of fish and significant negative effects on group size in both sea urchins and fish. We did not find any effect of fishing on fish size structure. To our knowledge this is the first study to compare sites under different amounts of fishing pressure that has demonstrated the negative effects of the aquarium trade on wild populations of reef fish, despite the widespread use of relatively nondestructive fishing methods.

    Nationell ämneskategori
    Biologiska vetenskaper
    Identifikatorer
    urn:nbn:se:uu:diva-90790 (URN)10.1046/j.1523-1739.2003.01522.x (DOI)000183077800036 ()
    Tillgänglig från: 2003-09-04 Skapad: 2003-09-04 Senast uppdaterad: 2017-12-14Bibliografiskt granskad
    7. Do egg size and parental care coevolve in fish?
    Öppna denna publikation i ny flik eller fönster >>Do egg size and parental care coevolve in fish?
    2005 (Engelska)Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 66, nr 6, s. 1499-1515Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    A phenomenon that has attracted a substantial theoretical and empirical interest is the positive relationship between egg size and the extent of parental care in fishes. Interestingly, despite the effort put into solving the causality behind this relationship over the past two decades it remains largely unsolved. Moreover, how general the positive relationship between egg size and parental care is among fishes is also poorly understood. In order to stimulate research exploring egg size and parental care variation in fishes, the potential selective forces from both natural and sexual selection on egg size and parental care are discussed. Recent empirical findings on how oxygen requirements and developmental times may differ between differently sized eggs are incorporated into a critical view of the current theory of this field. Furthermore, it is suggested that the up to now neglected effects of sexual selection, through both mate choice and sexual conflict, can have strong effects on the relationship between egg size and parental care in fishes. In light of the recent developments of comparative and experimental methods, future approaches that may improve the understanding of the relationship between egg size and care in fishes are suggested.

    Nationell ämneskategori
    Ekologi
    Identifikatorer
    urn:nbn:se:uu:diva-90791 (URN)10.1111/j.0022-1112.2005.00777.x (DOI)
    Tillgänglig från: 2003-09-04 Skapad: 2003-09-04 Senast uppdaterad: 2017-12-14
  • 29.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för evolutionsbiologi, Zooekologi.
    Male size determines reproductive output in a paternal mouthbrooding fish2002Ingår i: Animal Behaviour, ISSN 0003-3472, E-ISSN 1095-8282, Vol. 63, nr 4, s. 727-733Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Size can have strong effects on reproductive success in both males and females, and in many species large individuals are preferred as mates. To estimate the potential benefits from mate choice for size in both sexes, I studied the effects of the size of each sex on the reproductive output of pairs of Banggai cardinalfish, Pterapogon kauderni, a sexually monomorphic obligate paternal mouthbrooder. When pairs were allowed to form freely, a size-assortative mating pattern was observed and larger pairs had a higher reproductive output as determined by total clutch weight and egg size. To separate the potential benefits from mate choice for size for each sex, I subsequently used these pairs to form reversed size-assortative pairs, that is, the largest male paired to the smallest female and vice versa. I found a positive correlation between male size and clutch size: relatively heavier clutches were found in pairs where females were given a larger male. This suggests that the size of the male influences clutch weight. For egg size, however, the size of both sexes seemed important. The study reveals the benefits of mutual mate choice on size in this species: larger females provide larger eggs and larger males can brood heavier clutches. Furthermore, these results suggest that females differentially allocate resources into the eggs according to the size of the mate.

  • 30.
    Kolm, Niclas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Ahnesjö, Ingrid
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Do egg size and parental care coevolve in fish?2005Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 66, nr 6, s. 1499-1515Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A phenomenon that has attracted a substantial theoretical and empirical interest is the positive relationship between egg size and the extent of parental care in fishes. Interestingly, despite the effort put into solving the causality behind this relationship over the past two decades it remains largely unsolved. Moreover, how general the positive relationship between egg size and parental care is among fishes is also poorly understood. In order to stimulate research exploring egg size and parental care variation in fishes, the potential selective forces from both natural and sexual selection on egg size and parental care are discussed. Recent empirical findings on how oxygen requirements and developmental times may differ between differently sized eggs are incorporated into a critical view of the current theory of this field. Furthermore, it is suggested that the up to now neglected effects of sexual selection, through both mate choice and sexual conflict, can have strong effects on the relationship between egg size and parental care in fishes. In light of the recent developments of comparative and experimental methods, future approaches that may improve the understanding of the relationship between egg size and care in fishes are suggested.

  • 31.
    Kolm, Niclas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Amcoff, Mirjam
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Mann, Richard P.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Matematiska institutionen, Analys och tillämpad matematik.
    Arnqvist, Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Diversification of a Food-Mimicking Male Ornament via Sensory Drive2012Ingår i: Current Biology, ISSN 0960-9822, E-ISSN 1879-0445, Vol. 22, nr 15, s. 1440-1443Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The evolutionary divergence of sexual signals is often important during the formation of new animal species, but our understanding of the origin of signal diversity is limited [1, 2]. Sensory drive, the optimization of communication signal efficiency through matching to the local environment, has been highlighted as a potential promoter of diversification and speciation [3]. The swordtail characin (Corynopoma riisei) is a tropical fish in which males display a flag-like ornament that elicits female foraging behavior during courtship. We show that the shape of the male ornament covaries with female diet across natural populations. More specifically, natural populations in which the female diet is more dominated by ants exhibit male ornaments more similar to the shape of an ant. Feeding experiments confirm that females habituated to a diet of ants prefer to bite at male ornaments from populations with a diet more dominated by ants. Our results show that the male ornament functions as a "fishing lure" that is diversifying in shape to match local variation in female search images employed during foraging. This direct link between variation in female feeding ecology and the evolutionary diversification of male sexual ornaments suggests that sensory drive may be a common engine of signal divergence.

  • 32.
    Kolm, Niclas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Arnqvist, Göran
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Environmental correlates of diet in the swordtail characin (Corynopoma riisei, gill)2011Ingår i: Environmental Biology of Fishes, ISSN 0378-1909, E-ISSN 1573-5133, Vol. 92, nr 2, s. 159-166Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the sexually dimorphic swordtail characin (Corynopoma riisei, Gill), males are equipped with an opercular flag-ornament that has been suggested to function as a food-mimic since females bite at the ornament during courtship. However, virtually nothing is known about the diet in wild populations of this species. In this study, we first investigated composition of and variation in the diet of C. riisei across 18 different populations in Trinidad, using gut content analyses. We then related variation in gut content to habitat features of populations to investigate the potential link between environmental conditions and prey utilization. Our results showed that the dominating food type in the gut was various terrestrial invertebrates, both adults and larvae, but we also document substantial variation in prey types across populations. Furthermore, a canonical correlation analysis revealed a relationship between environmental characteristics and diet: populations from wider and more rapidly flowing streams with more canopy cover tended to have a diet based more on ants and mosquitoes while populations from narrow and slow flowing streams with little canopy cover tended to have a diet based more on springtails, mites and mayfly larvae. Our results add novel information on the ecology of this interesting fish and suggest the possibility of local adaptation reflecting differences in prey availability across natural populations.

  • 33.
    Kolm, Niclas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för evolutionsbiologi, Zooekologi.
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Sex-specific territorial behaviour in the Banggai cardinalfish, Pterapogon kauderni2004Ingår i: Environmental Biology of Fishes, ISSN 0378-1909, E-ISSN 1573-5133, Vol. 70, nr 4, s. 375-379Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In a field experiment, we studied how levels of aggression in males and females in established pairs of the Banggai cardinalfish were influenced by the sex of an experimentally introduced individual larger and more attractive than its resident counterpart. Contrary to previous studies on other cardinalfish species, and contrary to expectations in a sex role reversed species, the male was the main aggressor towards an intruder. Moreover, residents were more aggressive towards an intruder of the same sex as themselves. Furthermore, even though females often courted introduced, larger males, no intruder managed to take over the partnership of any resident. We suggest that our findings imply relatively equal sex roles in the Banggai cardinalfish and we discuss the evolution of sex specific territory defence and its significance in the Banggai cardinalfish as well as the implications of such behaviour in the interpretations of sex roles in general.

  • 34.
    Kolm, Niclas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för evolutionsbiologi, Zooekologi.
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för evolutionsbiologi, Zooekologi.
    Wild Populations of a Reef Fish Suffer from the “Nondestructive” Aquarium Trade Fishery2003Ingår i: Conservation Biology, ISSN 0888-8892, E-ISSN 1523-1739, Vol. 17, nr 3, s. 910-914Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The commercial fishery for coral reef fish for the aquarium trade has begun to change, at least in some parts of the world, from destructive methods such as cyanide and dynamite fishing to less-destructive methods such as hand-net fishing. However, data on the effects on wild populations of such relatively nondestructive methods is nonexistent. The Banggai cardinalfish (   Pterapogon kauderni ) is a paternal mouthbrooder living in groups of 2–200 individuals in the proximity of sea urchins (   Diadema setosum ). This fish has limited dispersal abilities because it lacks a pelagic larval phase, and it is believed to be endemic to the Banggai archipelago off the east coast of Sulawesi, Indonesia. Since its rediscovery in 1995, the Banggai cardinalfish has become a popular aquarium fish, and thousands have been exported—mainly to North America, Japan, and Europe. To study the effects of the aquarium trade fishery on wild populations of the Banggai cardinalfish, we performed a field study in which we quantified density, age distribution ( quantified as the ratio of numbers of juveniles to adults ) and habitat quality ( i.e., sea urchin density ) at eight sites in the Banggai archipelago. Through interviews with local fishers, we estimated the fishing pressure at each site and related this to data on fish density. We found a marginally significant negative effect of fishing pressure on density of fish and significant negative effects on group size in both sea urchins and fish. We did not find any effect of fishing on fish size structure. To our knowledge this is the first study to compare sites under different amounts of fishing pressure that has demonstrated the negative effects of the aquarium trade on wild populations of reef fish, despite the widespread use of relatively nondestructive fishing methods.

  • 35.
    Kolm, Niclas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Gonzalez-Voyer, Alejandro
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Brelin, Daniel
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för neurovetenskap, Fysiologi.
    Winberg, Svante
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för neurovetenskap, Fysiologi.
    Evidence for small scale variation in the vertebrate brain: mating strategy and sex affect brain size and structure in wild brown trout (Salmo trutta)2009Ingår i: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 22, nr 12, s. 2524-2531Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The basis for our knowledge of brain evolution in vertebrates rests heavily on empirical evidence from comparative studies at the species level. However, little is still known about the natural levels of variation and the evolutionary causes of differences in brain size and brain structure within-species, even though selection at this level is an important initial generator of macroevolutionary patterns across species. Here, we examine how early life-history decisions and sex are related to brain size and brain structure in wild populations using the existing natural variation in mating strategies among wild brown trout (Salmo trutta). By comparing the brains of precocious fish that remain in the river and sexually mature at a small size with those of migratory fish that migrate to the sea and sexually mature at a much larger size, we show, for the first time in any vertebrate, strong differences in relative brain size and brain structure across mating strategies. Precocious fish have larger brain size (when controlling for body size) but migratory fish have a larger cerebellum, the structure in charge of motor coordination. Moreover, we demonstrate sex-specific differences in brain structure as female precocious fish have a larger brain than male precocious fish while males of both strategies have a larger telencephalon, the cognitive control centre, than females. The differences in brain size and structure across mating strategies and sexes thus suggest the possibility for fine scale adaptive evolution of the vertebrate brain in relation to different life histories.

  • 36.
    Kolm, Niclas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Hoffman, Eric A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Olsson, Jens
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Limnologi.
    Group stability and homing behavior but no kin group sturcture in a coral reef fish2005Ingår i: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 16, nr 3, s. 521-527Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Understanding the reasons behind stable group formations has received considerable theoretical and empirical attention. Stable groups displaying homing behavior have been suggested to form as a result of, for instance, benefits from knowledge of the social or physical environment or through kin selection and the forming of kin groups. However, no one has disentangled preference for grouping in a familiar location from preference for grouping with familiar or related individuals. To investigate this, we conducted a series of field experiments and a group genetic analysis on the group-living Banggai cardinalfish (Pterapogon kauderni). We found homing behavior but no evidence for recognition of familiar group members. Instead, homing was based on the original location of their group rather than the individuals in that group. Moreover, we found no evidence for kin structures within these groups. We suggest that benefits from living in a known social environment drive homing behavior in this species and that homing behavior is not enough for the formation of kin group structures. Instead, our results suggest that kin recognition may be a prerequisite for the forming of kin groups.

  • 37.
    Kolm, Niclas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för evolutionsbiologi, Zooekologi.
    Olsson, Jens
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för evolutionsbiologi, Limnologi.
    Differential investment in the Banggai cardinalfish: can females adjust egg size close to egg maturation to match the attractiveness of a new partner?2003Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 63, nr S1, s. 144-151Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To test whether females can change their egg investment according to the different attractiveness ( i.e. size as measured by standard length, Ls) of a new mate after eggs have already matured in response to an earlier mate, female Banggai cardinalfish Pterapogon kauderni were first allowed to produce eggs for small (unattractive) or large (attractive) males. Then, when spawning was initiated, but prior to actual spawning, their partner was switched to either a significantly larger or a significantly smaller partner, respectively. A strong positive correlation between egg size and days until spawning with the second male was found for the females initially paired to a small and then a large male. Within a few days, these females apparently increased their egg size to match the attractiveness of their new male. No correlation between days until spawning and egg size in females initially paired to a large and then a small male, however was found, so apparently females were unable to adjust egg size in response to a decrease in mate attractiveness. Consequently, it is suggested that females can increase their egg size investment even after the onset of egg maturation and that this change can be quite rapid.

  • 38.
    Kolm, Niclas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Stein, R.W
    Mooers, A.
    Verspoor, J.J.
    Cunningham, J.A.
    Can sexual selection drive female life histories?: A comparative study on Galliform birds2007Ingår i: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 20, nr 2, s. 627-638Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Sexual selection has been identified as a major evolutionary force shaping male life history traits but its impact on female life history evolution is less clear. Here we examine the impact of sexual selection on three key female traits (body size, egg size and clutch size) in Galliform birds. Using comparative independent contrast analyses and directionaldiscreteanalyses, based on published data and a new genera-level supertree phylogeny of Galliform birds, we investigated how sexual selection [quantified as sexual size dimorphism (SSD) and social mating system (MS)] affects these three important female traits. We found that female body mass was strongly and positively correlated with egg size but not with clutch size, and that clutch size decreased as egg size increased. We established that SSD was related to MS, and then used SSD as a proxy of the strength of sexual selection. We found both a positive relationship between SSD and female body mass and egg size and that increases in female body mass and egg size tend to occur following increases in SSD in this bird order. This pattern of female body mass increases lagging behind changes in SSD, established using our directionaldiscreteanalysis, suggests that female body mass increases as a response to increases in the level of sexual selection and not simply through a strong genetic relationship with male body mass. This suggests that sexual selection is linked to changes in female life history traits in Galliformes and we discuss how this link may shape patterns of life history variation among species.

  • 39.
    Kotrschal, Alexander
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Lievens, Eva J. P.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Dahlbom, Josefin
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för neurovetenskap.
    Bundsen, Andreas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Semenova, Svetlana
    Sundvik, Maria
    Maklakov, Alexei A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Winberg, Svante
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för neurovetenskap, Fysiologi.
    Panula, Pertti
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Artificial Selection on Relative Brain Size Reveals a Positive Genetic Correlation Between Brain Size and Proactive Personality in the Guppy2014Ingår i: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 68, nr 4, s. 1139-1149Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Animal personalities range from individuals that are shy, cautious, and easily stressed (a "reactive" personality type) to individuals that are bold, innovative, and quick to learn novel tasks, but also prone to routine formation (a "proactive" personality type). Although personality differences should have important consequences for fitness, their underlying mechanisms remain poorly understood. Here, we investigated how genetic variation in brain size affects personality. We put selection lines of large- and small-brained guppies (Poecilia reticulata), with known differences in cognitive ability, through three standard personality assays. First, we found that large-brained animals were faster to habituate to, and more exploratory in, open field tests. Large-brained females were also bolder. Second, large-brained animals excreted less cortisol in a stressful situation (confinement). Third, large-brained animals were slower to feed from a novel food source, which we interpret as being caused by reduced behavioral flexibility rather than lack of innovation in the large-brained lines. Overall, the results point toward a more proactive personality type in large-brained animals. Thus, this study provides the first experimental evidence linking brain size and personality, an interaction that may affect important fitness-related aspects of ecology such as dispersal and niche exploration.

  • 40.
    Kotrschal, Alexander
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Rasanen, Katja
    Kristjansson, Bjarni K.
    Senn, Mike
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Extreme Sexual Brain Size Dimorphism in Sticklebacks: A Consequence of the Cognitive Challenges of Sex and Parenting?2012Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, nr 1, s. e30055-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Selection pressures that act differently on males and females produce numerous differences between the sexes in morphology and behaviour. However, apart from the controversial report that males have slightly heavier brains than females in humans, evidence for substantial sexual dimorphism in brain size is scarce. This apparent sexual uniformity is surprising given that sexually distinct selection pressures are ubiquitous and that brains are one of the most plastic vertebrate organs. Here we demonstrate the highest level of sexual brain size dimorphism ever reported in any vertebrate: male three-spined stickleback of two morphs in an Icelandic lake have 23% heavier brains than females. We suggest that this dramatic sexual size dimorphism is generated by the many cognitively demanding challenges that males are faced in this species, such as an elaborate courtship display, the construction of an ornate nest and a male-only parental care system. However, we consider also alternative explanations for smaller brains in females, such as life-history trade-offs. Our demonstration of unprecedented levels of sexual dimorphism in brain size in the three-spined stickleback implies that behavioural and life-history differences among the sexes can have strong effects also on neural development and proposes new fields of research for understanding brain evolution.

  • 41.
    Kotrschal, Alexander
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Rogell, Björn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Bundsen, Andreas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Svensson, Beatrice
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Zajitschek, Susanne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Evolutionsbiologi.
    Brännström, Ioana
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Evolutionsbiologi.
    Immler, Simone
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Evolutionsbiologi.
    Maklakov, Alexei A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    The benefit of evolving a larger brain: big-brained guppies perform better in a cognitive task2013Ingår i: Animal Behaviour, ISSN 0003-3472, E-ISSN 1095-8282, Vol. 86, nr 4, s. E4-E6Artikel i tidskrift (Refereegranskat)
  • 42.
    Kotrschal, Alexander
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Rogell, Björn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Bundsen, Andreas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Svensson, Beatrice
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Zajitschek, Susanne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Evolutionsbiologi.
    Brännström, Ioana Onut
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Evolutionsbiologi.
    Immler, Simone
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Evolutionsbiologi.
    Maklakov, Alexei A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Artificial selection on relative brain size in the guppy reveals costs and benefits of evolving a larger brain2013Ingår i: Current Biology, ISSN 0960-9822, E-ISSN 1879-0445, Vol. 23, nr 2, s. 168-171Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The large variation in brain size that exists in the animal kingdom has been suggested to have evolved through the balance between selective advantages of greater cognitive ability and the prohibitively high energy demands of a larger brain (the "expensive-tissue hypothesis" [1]). Despite over a century of research on the evolution of brain size, empirical support for the trade-off between cognitive ability and energetic costs is based exclusively on correlative evidence [2], and the theory remains controversial [3, 4]. Here we provide experimental evidence for costs and benefits of increased brain size. We used artificial selection for large and small brain size relative to body size in a live-bearing fish, the guppy (Poecilia reticulata), and found that relative brain size evolved rapidly in response to divergent selection in both sexes. Large-brained females outperformed small-brained females in a numerical learning assay designed to test cognitive ability. Moreover, large-brained lines, especially males, developed smaller guts, as predicted by the expensive-tissue hypothesis [1], and produced fewer offspring. We propose that the evolution of brain size is mediated by a functional trade-off between increased cognitive ability and reproductive performance and discuss the implications of these findings for vertebrate brain evolution.

  • 43.
    Kotrschal, Alexander
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Rogell, Björn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Maklakov, Alexei A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Kolm, Nichlas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Sex-specific plasticity in brain morphology depends on social environment of the guppy, Poecilia reticulata2012Ingår i: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 66, nr 11, s. 1485-1492Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The vertebrate brain is a remarkably plastic organ, which responds quickly to environmental changes. However, to date, studies investigating plasticity in brain morphology have focused mostly on the physical properties of the surrounding environment, and little is known about brain plasticity in response to the social environment. Moreover, sex differences in brain plasticity remain virtually unexplored. Here, we tested how the social environment influenced brain morphology in adult males and females using experimental manipulation of the sex composition of social pairs (same sex vs. mixed sex) in the guppy (Poecilia reticulata). We detected substantial sex-specific plasticity in both the overall brain size (controlling for body size) and separate brain structures. The brain size was larger in males that interacted with females, and female optic tectum was larger in female-only groups. Overall, females had larger olfactory bulbs and cerebellum in comparison to males. While net sexual dimorphism in the brain structure can be explained in light of the known differences in boldness and foraging behaviour between the sexes, our results also support that cognitive demands associated with courtship behaviour can lead to plastic changes in the brain size. Our findings demonstrate that not only social environment can generate rapid, plastic responses in the vertebrate brain but also that such responses can depend strongly on sex.

  • 44.
    Kotrschal, Alexander
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Sundström, L. Fredrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Brelin, D.
    Devlin, R. H.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Inside the heads of David and Goliath: environmental effects on brain morphology among wild and growth-enhanced coho salmon Oncorhynchus kisutch2012Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 81, nr 3, s. 987-1002Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Transgenic and wild-type individual coho salmon Oncorhynchus kisutch were reared in hatchery and near-natural stream conditions and their brain and structure sizes were determined. Animals reared in the hatchery grew larger and developed larger brains, both absolutely and when controlling for body size. In both environments, transgenics developed relatively smaller brains than wild types. Further, the volume of the optic tectum of both genotypes was larger in the hatchery animals and the cerebellum of transgenics was smaller when reared in near-natural streams. Finally, wild types developed a markedly smaller telencephalon under hatchery conditions. It is concluded that, apart from the environment, genetic factors that modulate somatic growth rate also have a strong influence on brain size and structure.

  • 45.
    Maklakov, Alexei A.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Immler, Simone
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Evolutionsbiologi.
    Gonzalez-Voyer, Alejandro
    Rönn, Johanna
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Brains and the city: big-brained passerine birds succeed in urban environments2011Ingår i: Biology Letters, ISSN 1744-9561, E-ISSN 1744-957X, Vol. 7, nr 5, s. 730-732Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Urban regions are among the most human-altered environments on Earth and they are poised for rapid expansion following population growth and migration. Identifying the biological traits that determine which species are likely to succeed in urbanized habitats is important for predicting global trends in biodiversity. We provide the first evidence for the intuitive yet untested hypothesis that relative brain size is a key factor predisposing animals to successful establishment in cities. We apply phylogenetic mixed modelling in a Bayesian framework to show that passerine species that succeed in colonizing at least one of 12 European cities are more likely to belong to big-brained lineages than species avoiding these urban areas. These data support findings linking relative brain size with the ability to persist in novel and changing environments in vertebrate populations, and have important implications for our understanding of recent trends in biodiversity.

  • 46.
    Maklakov, Alexei A.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Immler, Simone
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Evolutionsbiologi.
    Gonzalez-Voyer, Alejandro
    Rönn, Johanna
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Kolm, Niclas
    Brains and the city in passerine birds: re-analysis and confirmation of the original result2013Ingår i: Biology Letters, ISSN 1744-9561, E-ISSN 1744-957X, Vol. 9, nr 6, s. 20130859-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Our original paper [1] included two Bayesian analyses [2] of the association between brain size and the probability of a passerine species of bird breeding in the city centre—at the level of families and at the level of individual species—with both analyses suggesting the same pattern. It has since been brought to our attention that in one of the analyses at the level of individual species, the residual variance was not fixed to 1 resulting in overestimation of the variance. We re-ran the analysis using fixed residual variance and the results support the original conclusion that relative brain size is associated with breeding in the city centre (ln brain size: posterior mean, 324.53, 95% credibility interval, 52.61–601.35; ln body size: posterior mean, −276.22, 95% credibility interval, −490.60 to −70.32). Furthermore, we applied a complimentary approach using logistic regression to test whether brain size predicts breeding in the city centre (yes/no) without accounting for phylogeny. This analysis also resulted in a significant positive association between brain size and breeding in city centres (likelihood ratio tests: ln brain size: d.f. = 1, χ2 = 11.08, p = 0.0009; ln body size: d.f. = 1, χ2 = 11.26, p = 0.0008). Thus, our results are confirmed by both phylogenetic and non-phylogenetic analyses.

  • 47. Ridley, J.
    et al.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution.
    Freckleton, R.P.
    Gage, M.J.
    An unexpected influence of widely used significance thresholds on the distribution of reported P-values2007Ingår i: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 20, nr 3, s. 1082-1089Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We consider the problematic relationship between publication success and statistical significance in the light of analyses in which we examine the distribution of published probability (P) values across the statistical `significance' range, below the 5% probability threshold. P-values are often judged according to whether they lie beneath traditionally accepted thresholds (< 0.05, < 0.01, < 0.001, < 0.0001); we examine how these thresholds influence the distribution of reported absolute P-values in published scientific papers, the majority in biological sciences. We collected published P-values from three leading journals, and summarized their distribution using the frequencies falling across and within these four threshold values between 0.05 and 0. These published frequencies were then fitted to three complementary null models which allowed us to predict the expected proportions of P-values in the top and bottom half of each inter-threshold interval (i.e. those lying below, as opposed to above, each P-value threshold). Statistical comparison of these predicted proportions, against those actually observed, provides the first empirical evidence for a remarkable excess of probability values being cited on, or just below, each threshold relative to the smoothed theoretical distributions. The pattern is consistent across thresholds and journals, and for whichever theoretical approach used to generate our expected proportions. We discuss this novel finding and its implications for solving the problems of publication bias and selective reporting in evolutionary biology.

  • 48.
    Tsuboi, Masahito
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Gonzalez-Voyer, Alejandro
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Höglund, Jacob
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Populationsbiologi och naturvårdsbiologi.
    Kolm, Niclas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Ecology and mating competition influence sexual dimorphism in Tanganyikan cichlids2012Ingår i: Evolutionary Ecology, ISSN 0269-7653, E-ISSN 1573-8477, Vol. 26, nr 1, s. 171-185Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Sexual selection contributes strongly to the evolution of sexual dimorphism among animal taxa. However, recent comparative analyses have shown that evolution of sexual dimorphism can be influenced by extrinsic factors like mating system and environment, and also that different types of sexual dimorphism may present distinct evolutionary pathways. Investigating the co-variation among different types of sexual dimorphism and their association with environmental factors can therefore provide important information about the mechanisms generating variation in sexual dimorphism among contemporary species. Using phylogenetic comparative analyses comparing 49 species of Tanganyikan cichlid fishes, we first investigated the pairwise relationship between three types of sexual dimorphism [size dimorphism (SSD), colour dimorphism (COD) and shape dimorphism (SHD)] and how they were related to the strength of pre- and post-copulatory sexual selection. We then investigated the influence of ecological features on sexual dimorphism. Our results showed that although SSD was associated with the overall strength of sexual selection it was not related to other types of sexual dimorphism. Also, SSD co-varied with female size and spawning habitat, suggesting a role for female adaptations to spawn in small crevices and shells influencing SSD in this group. Further, COD and SHD were positively associated and both show positive relationships with the strength of sexual selection. Finally, the level of COD and SHD was related to habitat complexity. Our results thus highlight distinct evolutionary pathways for different types of sexual dimorphism and further that ecological factors have influenced the evolution of sexual dimorphism in Tanganyikan cichlid fishes.

  • 49.
    Tsuboi, Masahito
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Gonzalez-Voyer, Alejandro
    Kolm, Niclas
    Phenotypic integration of brain size and head morphology in Lake Tanganyika Cichlids2014Ingår i: BMC Evolutionary Biology, ISSN 1471-2148, E-ISSN 1471-2148, Vol. 14, s. 39-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background: Phenotypic integration among different anatomical parts of the head is a common phenomenon across vertebrates. Interestingly, despite centuries of research into the factors that contribute to the existing variation in brain size among vertebrates, little is known about the role of phenotypic integration in brain size diversification. Here we used geometric morphometrics on the morphologically diverse Tanganyikan cichlids to investigate phenotypic integration across key morphological aspects of the head. Then, while taking the effect of shared ancestry into account, we tested if head shape was associated with brain size while controlling for the potentially confounding effect of feeding strategy. Results: The shapes of the anterior and posterior parts of the head were strongly correlated, indicating that the head represents an integrated morphological unit in Lake Tanganyika cichlids. After controlling for phylogenetic non-independence, we also found evolutionary associations between head shape, brain size and feeding ecology. Conclusions: Geometric morphometrics and phylogenetic comparative analyses revealed that the anterior and posterior parts of the head are integrated, and that head morphology is associated with brain size and feeding ecology in Tanganyikan cichlid fishes. In light of previous results on mammals, our results suggest that the influence of phenotypic integration on brain diversification is a general process.

  • 50.
    Zwoinska, Martyna K.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Kolm, Niclas
    Maklakov, Alexei A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Sex differences in cognitive ageing: Testing predictions derived from life-history theory in a dioecious nematode2013Ingår i: Experimental Gerontology, ISSN 0531-5565, E-ISSN 1873-6815, Vol. 48, nr 12, s. 1469-1472Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Life-history theory maintains that organisms allocate limited resources to different traits to maximize fitness. Learning ability and memory are costly and known to trade-off with longevity in invertebrates. However, since the relationship between longevity and fitness often differs between the sexes, it is likely that sexes will differentially resolve the trade-off between learning and longevity. We used an established associative learning paradigm in the dioecious nematode Caenorhabditis remanei, which is sexually dimorphic for lifespan, to study age-related learning ability in males and females. In particular, we tested the hypothesis that females (the shorter-lived sex) show higher learning ability than males early in life but senesce faster. Indeed, young females outperformed young males in learning a novel association between an odour (butanone) and food (bacteria). However, while learning ability and offspring production declined rapidly with age in females, males maintained high levels of these traits until mid-age. These results not only demonstrate sexual dimorphismin age-related learning ability but also suggest that it conforms to predictions derived from the life-history theory.

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