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  • 1.
    Ah-King, Malin
    et al.
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Arts, Centre for Gender Research.
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Problemet med "könsroller" kvarstår2013In: Tidskrift för Genusvetenskap, ISSN 1654-5443, E-ISSN 2001-1377, no 1, p. 136-137Article in journal (Other academic)
  • 2.
    Ah-King, Malin
    et al.
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Arts, Centre for Gender Research.
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    The "Sex Role" Concept: An Overview and Evaluation2013In: Evolutionary biology, ISSN 0071-3260, E-ISSN 1934-2845, Vol. 40, no 4, p. 461-470Article, review/survey (Refereed)
    Abstract [en]

    "Sex roles" are intuitively associated to stereotypic female and male sexual strategies and in biology, the term "sex role" often relates to mating competition, mate choice or parental care. "Sex role reversals" imply that the usual typological pattern for a population or species is deviates from a norm, and the meaning of "sex role reversal" thus varies depending upon whatever is the usual pattern of sex-typical behavior in a given taxon. We identify several problems with the current use of the "sex role" concept. (1) It is typological and reflects stereotypic expectations of the sexes. (2) The term "sex role" parses continuous variation into only two categories, often obscuring overlap, between the sexes in behavior and morphology, and variability in relation to ecological circumstances. (3) Common generalizations such as "sex role as seen in nature" mask variation upon which selection may act. (4) The general meaning of "sex roles" in society (i.e. "socially and culturally defined prescriptions and beliefs about the behavior and emotions of men and women") is contrary to biological "sex role" concepts, so that confusing the two obscure science communication in society. We end by questioning the validity of the "sex role" concept in evolutionary biology and recommend replacing the term "sex role" with operational descriptions.

  • 3.
    Ah-King, Malin
    et al.
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Arts, Centre for Gender Research.
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Vad kan vi lära av biologisk forskning om “könsroller”?2012In: Tidskrift för Genusvetenskap, ISSN 1654-5443, E-ISSN 2001-1377, Vol. 6, no 4, p. 51-56Article in journal (Refereed)
  • 4.
    AHNESJO, I
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology.
    TEMPERATURE AFFECTS MALE AND FEMALE POTENTIAL REPRODUCTIVE RATES DIFFERENTLY IN THE SEX-ROLE REVERSED PIPEFISH, SYNGNATHUS-TYPHLE1995In: BEHAVIORAL ECOLOGY, ISSN 1045-2249, Vol. 6, no 2, p. 229-233Article in journal (Other academic)
    Abstract [en]

    The differences in potential reproductive rate between the sexes can be used to predict the operational sex ratio and the patterns and intensity of mating competition and hence sexual selection in a population. This article describes how one environmental

  • 5.
    Ahnesjo, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology.
    Apparent resource competition among embryos in the brood pouch of a male pipefish1996In: BEHAVIORAL ECOLOGY AND SOCIOBIOLOGY, ISSN 0340-5443, Vol. 38, no 3, p. 167-172Article in journal (Other academic)
    Abstract [en]

    Embryo success was studied in the paternally brooding pipefish Syngnathus typhle. During brooding, which lasts about a month, males provide embryos in their brood pouch with nutrients and oxygen via a placenta-like structure. Egg size depends on female si

  • 6.
    Ahnesjo, Ingrid
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Craig, J. F.
    The biology of Syngnathidae: pipefishes, seadragons and seahorses2011In: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 78, no 6, p. 1597-1602Article in journal (Other academic)
  • 7.
    Ahnesjo, Ingrid
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology.
    Kvarnemo, C
    Merilaita, S
    Using potential reproductive rates to predict mating competition among individuals qualified to mate2001In: BEHAVIORAL ECOLOGY, ISSN 1045-2249, Vol. 12, no 4, p. 397-401Article in journal (Refereed)
    Abstract [en]

    The potential reproductive rate (PRR), which is the offspring production per unit time each sex would achieve if unconstrained by mate availability, often differs between the sexes. An increasing sexual difference in PRR predicts an intensified mating com

  • 8.
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Behavioural temperature preference in a brooding male pipefish Syngnathus typhle2008In: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 73, no 4, p. 1039-1045Article in journal (Refereed)
    Abstract [en]

    In the broad-nosed pipefish Syngnathus typhle, brooding males positioned themselves significantly more often towards the warmer part (18 degrees C) of an aquarium. whereas females were indifferent in this respect. This behavioural temperature preference may increase male brooding rate and indirectly influence patterns of mating competition. (c) 2008 The Author Journal compilation (c) 2008 The Fisheries Society of the British Isles.

  • 9.
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Bokrecension av Retorik för naturvetare: skrivande som fördjupar lärandet2014In: Högre Utbildning, ISSN 2000-7558, E-ISSN 2000-7558, Vol. 4, no 1, p. 83-85Article, book review (Other academic)
  • 10.
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Equal Opportunity for Sexual Evolution2011In: BioScience, ISSN 0006-3568, E-ISSN 1525-3244, Vol. 61, no 8, p. 641-642Article, book review (Other academic)
  • 11.
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics.
    Fewer Newborn Result In Superior Juveniles In The Paternally Brooding Pipefish Syngnathus-Typhle L1992In: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 41, no Suppl. B, p. 53-63Article in journal (Refereed)
  • 12.
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Mate Choice in Males and Females2010In: Encyclopedia of Animal Behavior / [ed] Michael D. Breed and Janice Moore, Oxford: Academic Press, 2010, p. 394-398Chapter in book (Other academic)
    Abstract [en]

    Finding a ‘dream mate’ is important for fitness in many sexually reproducing animals because half the genome of the offspring will come from this mate. Individuals that choose their mates carefully may gain both direct benefits (i.e., good care, territories, and other resources) and indirect benefits (genes that improve offspring viability or attractiveness). Mate choices occur in both sexes and the same individuals can be both choosy and competitive. Mate choice and mating competition often result in sexual selection and the evolution of secondary sexual characters. Mate choice is interactive, context dependent, operates on multiple traits, and varies in time and space.

  • 13.
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Seahorses and Their Relatives2010In: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 77, no 1, p. 308-309Article, book review (Other academic)
  • 14.
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology.
    Sex-role reversal in two pipefish (Syngnathidae) species: paternal care and male limitation of female reproductive success1989Doctoral thesis, comprehensive summary (Other academic)
  • 15.
    Ahnesjö, Ingrid
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Forsgren, Elisabet
    Norsk institutt for naturforskning i Trondheim, Norway.
    Karlsson, Anna
    Enheten för biologisk mångfald och områdesskydd, Havs och Vattenmyndigheten, Göteborg.
    Kvarnemo, Charlotta
    Zoologi, Göteborgs universitet, Göteborg.
    Magnhagen, Carin
    Fiskbiologi, Sveriges lantbruksuniversitet (SLU), Umeå.
    Rosenqvist, Gunilla
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Natural Resources and Sustainable Development. Etologi, NTNU, Trondheim, Norway.
    Östlund Nilsson, Sara
    Nasjonalbiblioteket, Oslo, Norway.
    En beteende-ekologisk forskningsperiod på Klubbans biologiska station: Rapport från återträff med Doktorer som disputerade (1983-2001) på avhandlingar med fältarbete på Klubbans Biologiska station. I en värld av kantnålar, stubbar, spiggar och nudingar.2018Report (Other (popular science, discussion, etc.))
    Abstract [en]

    We had the fortune as PhD-students and scientists in Animal Ecology at Uppsala University, to spend joyful and creative field work summers at Klubban Biological Station, during the 1980-90’s. A reunion in June 2018 resulted in this report highlighting research on pipefishes, gobies, sticklebacks and nudibranchs. Our research on these animals have provided novel insights and knowledge of the process of sexual selection and paternal care. These animals have, in many aspects, now become model organisms in evolutionary behavioral ecology in marine environments. Our list of publications provides many examples of how environmental factors influence how sexual selection and mate choice operate, how predictors like potential reproductive rates, operational sex ratios work and how male parental care is prominent in influencing selection. This research, that started at Klubban, has broadened our understanding of the ecological importance of shallow marine areas. The evolutionary understanding of how males and females can behave and how adaptive traits are selected in interaction with social and an increasingly changing ambient environment is in focus in our continued scientific endeavors. We have happily compiled this report illustrating how science and scientist can stimulate each other at a wonderful place like Klubban Biological Station, with the access to amazing organisms like pipefishes, gobies, sticklebacks and nudibranchs.

  • 16.
    Ahnesjö, Ingrid
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Braga Goncalves, Ines
    Mate Choice in Males and Females2017In: Reference Module in Life Sciences, Elsevier, 2017, p. 394-398Chapter in book (Other academic)
    Abstract [en]

    To find a “dream mate” is important for fitness in all sexually reproducing animals because half of the genome of one’s offspring comes from the chosen mate. Individuals that choose their mates may gain both direct benefits (ie, care or other resources) and indirect benefits (genes improving offspring viability or attractiveness). Mate choice occurs in males and females, and individuals may simultaneously be choosy and compete to be chosen. Processes that often result in sexual selection and in the evolution of secondary sexual characters. Mate choice is context-dependent, operates on multiple traits and varies in time and space.

  • 17.
    Ahnesjö, Ingrid
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Braga Goncalves, Ines
    Mate choice in males and females2019In: Encyclopedia of Animal Behavior / [ed] Choe J.C., Elsevier, 2019, 2, p. 432-440Chapter in book (Refereed)
    Abstract [en]

    To find a “dream mate” is important for fitness in all sexually reproducing animals because half of the genome of one’soffspring comes from the chosen mate. Individuals that choose their mates may gain both direct benefits (i.e., care or other resources) and indirect benefits (genes that improve offspring viability or attractiveness). Mate choice occurs in males and females, and individuals may both be choosy and compete to be chosen. Both processes often result in sexual selection and in the evolution of secondary sexual characters. Mate choice is context-dependent, operates on multiple traits and varies in time and space.

  • 18.
    Ahnesjö, Ingrid
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Forsgren, Elisabet
    Kvarnemo, Charlotta
    Variation in sexual selection in fishes2008In: Fish Behaviour / [ed] Carin Magnhagen, Victoria A. Braithwaite, Elisabet Forsgren, B.G. Kapoor, Enfield: Science Publishers Inc., 2008, p. 303-335Chapter in book (Refereed)
  • 19.
    Ahnesjö, Ingrid
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics.
    Vincent, Amanda
    Alatalo, Rauno
    Halliday, Tim
    Sutherland, William J
    The role of females in influencing mating patterns1993In: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 4, no 2, p. 187-189Article in journal (Refereed)
  • 20.
    Berglund, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Rosenqvist, Gunilla
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Svensson, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Mate choice, fecundity and sexual dimorphism in two pipefish species (Syngnathidae)1986In: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 19, no 4, p. 301-307Article in journal (Refereed)
    Abstract [en]

    In order to understand the causes of sexual dimorphism, mate choice and size-related fecundity were studied in two pipefish species, Syngnathus typhle and Nerophis ophidion. Sexual dimorphism is more pronounced in N. ophidion; females are larger, have sexual colourings, and are more active during courtship. In S. typhle the sexes are alike in all these respects. Males brood their offspring in both species. In N. ophidion fecundity was positively correlated with both body size and the amount of sexual colouring in females. In males no correlation between body size and fecundity, or between body size and embryo size existed. Predictably, in mate choice experiments with equal-sized females, males chose females with more extensive sexual colourings. We explain sexual dimorphism in this species as a consequence of both natural selection (fecundity increases with size in females but not in males) and sexual selection (males prefer larger females). We argue that sexual size dimorphism did not evolve by selection minimizing overlap in food niches between the sexes, because food production is high in the Zostera beds where the fishes live, and no size dimorphism was found in the sympatrically occurring S. typhle. Furthermore, in N. ophidion dimorphism is not greater in a particular mouth character than in overall body size. In S. typhle egg size and the average number of eggs transferred per spawning were positively correlated with female body size. Apparently more energy per offspring was provided by larger males than by smaller males, and larger males also carried more offspring. As predicted, large mates were preferred by both sexes in mate choice experiments. This is explicable in terms of both natural selection (fecundity increases with size in both sexes) and sexual selection (both sexes prefer large mates). As a consequence of selection acting in the same direction in both sexes, sexual dimorphism is absent in S. typhle.

  • 21.
    Berglund, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Rosenqvist, Gunilla
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Svensson, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Multiple matings and paternal brood care in the pipefish Syngnathus typhle1988In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 51, no 2, p. 184-188Article in journal (Refereed)
  • 22.
    Berglund, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Rosenqvist, Gunilla
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Svensson, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Reproductive success of females limited by males in two pipefish species1989In: American Naturalist, ISSN 0003-0147, E-ISSN 1537-5323, Vol. 133, no 4, p. 506-516Article in journal (Refereed)
    Abstract [en]

    We investigate whether males limit the reproductive success of females in the two pipefish species Syngnathus typhle and Nerophis ophidion. Syngnathus typhle is sexually monomorphic, and courtship behavior does not differ between the sexes. In N. ophidion, on the contrary, females are larger, more colorful, and more active during courtship, possessing appearance-enlarging skin folds. In both species, males brood the offspring on their bodies, one internally and one externally. Males do not invest more energy in reproduction than do females, and in the sexually dimorphic species, males invest even less than females do. Natural sex ratios are equal in both species. Experimentally, we provided each female with an excess of males (i.e., three), in order to measure a female's maximal reproductive rate, and found that females of both species produced more eggs, or produced them at a faster rate, than naturally available males could care for. Within the time span of one male pregnancy, S. typhle females filled an average of 1.9 males and N. ophidion an average of 1.8 males; both numbers are significantly more than one (which is the average mate availability in natural populations). Measured in another way, during one male pregnancy, S. typhle and N. ophidion females both produced 41% more eggs than needed to fill a male, significantly more than no egg surplus in both species. Therefore, brood space and the rate of embryonic development limit female reproduction in these species. There was no significant difference between the species, however. Syngnathus typhle males might be expected to be less limiting than N. ophidion males, but sexual size dimorphism may be absent in S. typhle because, by contrast with N. ophidion, larger males enjoy greater reproductive success. Directional selection for increased male size may decrease sexual size dimorphism in S. typhle. At any rate, the limitation of the reproductive success of one sex by the other seems to be a necessary but not sufficient prerequisite for the evolution of sexual dimorphism and "sex roles."

  • 23.
    Berglund, Anders
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Rosenqvist, Gunilla
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Svensson, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Reversed sex-roles and parental energy investment in zygotes of two pipefish (Syngnathidae) species1986In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 29, no 3, p. 209-215Article in journal (Refereed)
  • 24. Braga Goncalves, Ines
    et al.
    Mobley, Kenyon B.
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Sagebakken, Gry
    Jones, Adam G.
    Kvarnemo, Charlotta
    Reproductive compensation in broad-nosed pipefish females2010In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 277, no 1687, p. 1581-1587Article in journal (Refereed)
    Abstract [en]

    The differential allocation hypothesis assumes that animals should weigh costs and benefits of investing into reproduction with a current mate against the expected quality of future mates, and predicts that they should invest more into reproduction when pairing with a high-quality mate. In the broad-nosed pipefish (Syngnathus typhle), males care for the embryos in a brood pouch and females compete for access to male mating partners. Both sexes prefer mating with large partners. In the present study, we show that the same female provides both large and small mating partners with eggs of similar size, weight and lipid content when mated to two males in succession. Importantly, however, eggs provided to small males (less preferred) had higher egg protein content (11% more) than those provided to large males (preferred). Thus, contrary to the differential allocation hypothesis, eggs did not contain more resources when females mated with a larger male. Instead, the pattern observed in our results is consistent with a compensatory reproductive strategy.

  • 25. Goncalves, I. Braga
    et al.
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal Ecology.
    Kvarnemo, C.
    The relationship between female body size and egg size in pipefishes2011In: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 78, no 6, p. 1847-1854Article in journal (Refereed)
    Abstract [en]

    Comparing five species of pipefish, egg size was significantly larger in species with brood pouches (Syngnathus typhle, Syngnathus acus and Syngnathus rostellatus) than in species without brood pouches (Entelurus aequoreus and Nerophis ophidion). Egg size correlated positively with female body size in species with brood pouches, but was similar across female sizes in the species lacking pouches. These results may reflect differences in offspring competition as a consequence of variable offspring relatedness within a brood, due to the mating systems adopted by the different species and the presence or absence of a brood pouch.

  • 26. Goncalves, Ines Braga
    et al.
    Ahnesjo, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Kvarnemo, Charlotta
    Embryo oxygenation in pipefish brood pouches: novel insights2015In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 218, no 11, p. 1639-1646Article in journal (Refereed)
    Abstract [en]

    The pipefish brood pouch presents a unique mode of parental care that enables males to protect, osmoregulate, nourish and oxygenate the developing young. Using a very fine O-2 probe, we assessed the extent to which males of the broad-nosed pipefish (Syngnathus typhle) oxygenate the developing embryos and are able to maintain pouch fluid O-2 levels when brooding in normoxia (100% O-2 saturation) and hypoxia (40% O-2 saturation) for 24 days. In both treatments, pouch fluid-O-2 saturation levels were lower compared with the surrounding water and decreased throughout the brooding period, reflecting greater offspring demand for O-2 during development and/or decreasing paternal ability to provide O-2 to the embryos. Male condition (hepatosomatic index) was negatively affected by hypoxia. Larger males had higher pouch fluid O-2 saturation levels compared with smaller males, and levels were higher in the bottom section of the pouch compared with other sections. Embryo size was positively correlated with O-2 availability, irrespective of their position in the pouch. Two important conclusions can be drawn from our findings. First, our results highlight a potential limitation to brooding within the pouch and dismiss the notion of closed brood pouches as well-oxygenated structures promoting the evolution of larger eggs in syngnathids. Second, we provide direct evidence that paternal care improves with male size in this species. This finding offers an explanation for the documented strong female preference for larger partners because, in terms of oxygenation, the brood pouch can restrict embryo growth.

  • 27.
    Goncalves, Ines Braga
    et al.
    Univ Zurich, Dept Evolutionary Biol & Environm Studies, Anim Behav, Winterthurerstr 190, CH-8057 Zurich, Switzerland.;Univ Gothenburg, Dept Biol & Environm Sci, POB 463, S-40530 Gothenburg, Sweden..
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Kvarnemo, Charlotta
    Univ Gothenburg, Dept Biol & Environm Sci, POB 463, S-40530 Gothenburg, Sweden..
    Evolutionary ecology of pipefish brooding structures: embryo survival and growth do not improve with a pouch2016In: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 6, no 11, p. 3608-3620Article in journal (Refereed)
    Abstract [en]

    For animals that reproduce in water, many adaptations in life-history traits such as egg size, parental care, and behaviors that relate to embryo oxygenation are still poorly understood. In pipefishes, seahorses and seadragons, males care for the embryos either in some sort of brood pouch, or attached ventrally to the skin on their belly or tail. Typically, egg size is larger in the brood pouch group and it has been suggested that oxygen supplied via the pouch buffers the developing embryos against hypoxia and as such is an adaptation that has facilitated the evolution of larger eggs. Here, using four pipefish species, we tested whether the presence or absence of brood pouch relates to how male behavior, embryo size, and survival are affected by hypoxia, with normoxia as control. Two of our studied species Entelurus aequoreus and Nerophis ophidion (both having small eggs) have simple ventral attachment of eggs onto the male trunk, and the other two, Syngnathus typhle (large eggs) and S. rostellatus (small eggs), have fully enclosed brood pouches on the tail. Under hypoxia, all species showed lower embryo survival, while species with brood pouches suffered greater embryo mortality compared to pouchless species, irrespective of oxygen treatment. Behaviorally, species without pouches spent more time closer to the surface, possibly to improve oxygenation. Overall, we found no significant benefits of brood pouches in terms of embryo survival and size under hypoxia. Instead, our results suggest negative effects of large egg size, despite the protection of brood pouches.

  • 28.
    Goncalves, Ines Braga
    et al.
    Univ Zurich, Inst Evolutionary Biol & Environm Studies, Anim Behav, CH-8057 Zurich, Switzerland.;Univ Gothenburg, Dept Biol & Environm Sci, S-40530 Gothenburg, Sweden..
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Kvarnemo, Charlotta
    Univ Gothenburg, Dept Biol & Environm Sci, S-40530 Gothenburg, Sweden..
    The evolutionary puzzle of egg size, oxygenation and parental care in aquatic environments2015In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 282, no 1813, article id 20150690Article in journal (Refereed)
    Abstract [en]

    Offspring fitness generally improves with increasing egg size. Yet, eggs of most aquatic organisms are small. A common but largely untested assumption is that larger embryos require more oxygen than they can acquire through diffusion via the egg surface, constraining egg size evolution. However, we found no detrimental effects of large egg size on embryo growth and survival under hypoxic conditions. We tested this in the broad-nosed pipelish, Syngnathus typhle, whose males provide extensive care (nourishment, osmoregulation and oxygenation) to their young in a brood pouch on their bodies. We took advantage of this species' pronounced variation in egg size, correlating positively with female size, and tested the effect of hypoxia (40% dissolved oxygen) versus fully oxygenated (100%) water on embryo size and survival of large versus small eggs after 18 days of paternal brooding. Egg size did not affect embryo survival, regardless of O-2 treatment. While hypoxia affected embryo size negatively, both large and small eggs showed similar reductions in growth. Males in hypoxia ventilated more and males with large eggs swam more, but neither treatment affected their position in the water column. Overall, our results call into question the most common explanation for constrained egg size evolution in aquatic environments.

  • 29. Goncalves, Ines Braga
    et al.
    Mobley, Kenyon B.
    Ahnesjo, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Sagebakken, Gry
    Jones, Adam G.
    Kvarnemo, Charlotta
    Effects of mating order and male size on embryo survival in a pipefish2015In: Biological Journal of the Linnean Society, ISSN 0024-4066, E-ISSN 1095-8312, Vol. 114, no 3, p. 639-645Article in journal (Refereed)
    Abstract [en]

    In species that provide parental care, individuals should invest adaptively in their offspring in relation to the pre- and post-zygotic care provided by their partners. In the broad-nosed pipefish, Syngnathus typhleL., females transfer large, nutrient-rich eggs into the male brood pouch during mating. The male broods and nourishes the embryos for several weeks before independent juveniles emerge at parturition. Given a choice, females clearly prefer large partners. Yet, females provide protein-richer eggs when the same individual mates with a smaller than a larger male. In the present study, we allowed each female to mate with one small and one large male, in alternated order. We found a strong effect of female mating order, with larger clutches and higher embryo mortality in first- than second-laid broods, which may suggest that eggs over-ripen in the ovaries or reflect the negative effects of high embryo density in the brood pouch. In either case, this effect should put constraints on the possibility of a female being selective in mate choice. We also found that small and large males produced embryos of similar size and survival, consistent with the reproductive compensation hypothesis, suggesting that, in this species, larger males provide better nourishment to the embryos than smaller males.(c) 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114, 639-645.

  • 30.
    Kolm, Niclas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Do egg size and parental care coevolve in fish?2005In: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 66, no 6, p. 1499-1515Article in journal (Refereed)
    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.
    Kvarnemo, C
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology.
    Ahnesjo, I
    The dynamics of operational sex ratios and competition for mates1996In: TRENDS IN ECOLOGY & EVOLUTION, Vol. 11, no 10, p. 404-408Article, book review (Other academic)
    Abstract [en]

    In sexually reproducing animals, individuals of one sex may have to compete for access to mating partners of the opposite sex. The operational sex ratio (OSR) is central in predicting the intensity of mating competition and which sex is competing for whic

  • 32. Kvarnemo, C.
    et al.
    Mobley, K. B.
    Partridge, C.
    Jones, A. G.
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal Ecology.
    Evidence of paternal nutrient provisioning to embryos in broad-nosed pipefish Syngnathus typhle2011In: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 78, no 6, p. 1725-1737Article in journal (Refereed)
    Abstract [en]

    In two experiments, radioactively labelled nutrients (either H-3-labelled amino-acid mixture or C-14-labelled glucose) were tube-fed to brooding male Syngnathus typhle. Both nutrients were taken up by the males and radioactivity generally increased in the brood pouch tissue with time. Furthermore, a low but significant increase of H-3-labelled amino acids in embryos was found over the experimental interval (48 h), whereas in the C-14-glucose experiment the radioactivity was taken up by the embryos but did not increase over the experimental time (320 min). Uptake of radioisotopes per embryo did not differ with embryo size. A higher uptake mg(-1) tissue of both H-3-labelled amino acids and C-14-labelled glucose was found in smaller embryos, possibly due to a higher relative metabolic rate or to a higher surface-area-to-volume ratio compared to larger embryos. Uptake in embryos was not influenced by male size, embryonic developmental advancement or position in the brood pouch. It is concluded that brooding males provide amino acids, and probably also glucose, to the developing embryos in the brood pouch.

  • 33.
    Kvarnemo, Charlotta
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology.
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology, Animal Ecology.
    Operational sex ratios and mating competition. Chapter 182002In: Sex ratios: concepts and research methods, Cambridge University Press, 2002, p. 366-382Chapter in book (Refereed)
  • 34. Mayer, Ian
    et al.
    Rosenqvist, Gunilla
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Borg, Bertil
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Schulz, Rüdiger W.
    Plasma-levels of sex steroids in 3 species of pipefish (Syngnathidae)1993In: Canadian Journal of Zoology, ISSN 0008-4301, E-ISSN 1480-3283, Vol. 71, no 9, p. 1903-1907Article in journal (Refereed)
    Abstract [en]

    The pipefishes (Syngnathidae) are marine teleosts in which the males brood the young. In some species sex-role reversal occurs when, contrary to the usual pattern, females compete more intensely than males for access to mates. This paper reports an investigation of the sex hormones of males and females to see whether they deviate from the ''normal'' teleost pattern. To that end, plasma levels of the androgens testosterone (T), 11-ketotestosterone (OT), 11beta-hydroxytestosterone, 11-ketoandrostenedione, and 11beta-hydroxyandrostenedione (OHA), together with 17alpha-hydroxy-20beta-dihydroprogesterone (17,20-P) and 17beta-estradiol (E2), were measured by means of radioimmunoassay in three species of pipefish: Nerophis ophidion, Syngnathus typhle, and Syngnathus acus. Plasma levels of OT, the dominant circulating androgen in breeding males of most teleost species, was found to be highest in breeding males and low or non-detectable later in the brooding males. This observed decline in male OT levels from the prespawning to the postspawning (=brooding) period is in general agreement with what has been found in other teleosts. In both breeding and brooding S. acus males, T was quantitatively the dominant androgen, whereas OHA was the major androgen in S. acus females, as well as in the females and breeding or brooding males of both S. typhle and N. ophidion. In breeding S. acus and S. typhle males the levels of T, OHT, and OT were higher than in corresponding brooding males and females. The 17,20-P level was below detection limit. E2 was also usually non-detectable, but was most consistently found in breeding Syngnathus males.

  • 35.
    Mobley, Kenyon
    et al.
    Department of Ecology and Environmental Science, Umeå university.
    Kvarnemo, Charlotta
    Department of Zoology, Göteborg University.
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal Ecology.
    Partridge, Charlyn
    Department of Biology, Texas A&M University, USA.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal Ecology.
    Jones, Adam G.
    Department of Biology, Texas A&M University, USA.
    The effect of maternal body size on embryo survivorship in the broods of pregnant male pipefish2011In: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 65, no 6, p. 1169-1177Article in journal (Refereed)
    Abstract [en]

    The occurrence of male pregnancy in the family Syngnathidae (seahorses, pipefishes, and sea dragons) provides an exceptionally fertile system in which to investigate issues related to the evolution of parental care. Here, we take advantage of this unique reproductive system to study the influence of maternal body size on embryo survivorship in the brood pouches of pregnant males of the broad-nosed pipefish, Syngnathus typhle. Males were mated with either two large females, two small females, a large then a small female, or a small then a large female. Our results show that offspring survivorship depends on an interaction between female body size and the number of eggs transferred by the female. Eggs of larger females deposited in large numbers are more likely to result in viable offspring than eggs of smaller females laid in large numbers. However, when females deposited smaller numbers of eggs, the eggs from smaller females were more likely to produce viable offspring compared to those from larger females. We found no evidence that this result was based on mating order, the relative sizes of competing females, or egg characteristics such as dry weight of eggs. Additionally, male body size did not significantly influence the survivorship of offspring during brooding. Our results suggest that the factors underlying offspring survivorship in pipefish may be more complex than previously believed, with multiple factors interacting to determine the fitness of individual offspring within the broods of pregnant males.

  • 36.
    Ostlund, S
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology.
    Ahnesjo, I
    Female fifteen-spined sticklebacks prefer better fathers1998In: ANIMAL BEHAVIOUR, ISSN 0003-3472, Vol. 56, p. 1177-1183Article in journal (Other academic)
    Abstract [en]

    We studied how male fifteen-spined sticklebacks, Spinachia spinachia, vary in paternal competence, whether males advertise their competence and whether females prefer better fathers. In this species the male alone provides care for the offspring through n

  • 37. Partridge, Charlyn
    et al.
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Kvarnemo, Charlotta
    Mobley, B
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Jones, G
    The effect of perceived female parasite load on post-copulatory male choice in a sex-role-reversed pipefish2009In: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 63, no 3, p. 345-354Article in journal (Refereed)
    Abstract [en]

    The last several decades of research in behavioral ecology have resulted in a deeper appreciation of post-mating processes and sexual conflict in sexual selection. One of the most controversial aspects of sexual selection is cryptic mate choice. Here, we take advantage of male pregnancy in a sex-role-reversed pipefish (Syngnathus typhle) to quantify cryptic choice based on perceived parasite load and other sources of variance in female fitness. Studies have shown that S. typhle males preferentially mate with females with lower parasite loads and that a male's perception of female parasite load can be altered by tattooing females. We manipulated the apparent parasite load of females in controlled mating experiments to test the hypothesis that post-copulatory sexual selection is dependent on a male's perception of female parasite load in pipefish. Our results provided no evidence for cryptic male choice based on perceived female parasite load. However, we found evidence that eggs from larger females were more likely to result in viable offspring than eggs from smaller females and that the first female to mate with a male transferred more eggs per copulation on average. Overall, our results show that potential for post-copulatory sexual selection does exist in pipefish, but the male's perception of female parasite load does not play a major role in this process.

  • 38. Sagebakken, Gry
    et al.
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal Ecology.
    Goncalves, Ines Braga
    Kvarnemo, Charlotta
    Multiply mated males show higher embryo survival in a paternally caring fish2011In: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 22, no 3, p. 625-629Article in journal (Refereed)
    Abstract [en]

    We explored the effects of multiple mates on male reproductive success in a species with male parental care in which an increase in the number of female mating partners does not increase the number of eggs received. The broad-nosed pipefish (Syngnathus typhle) has a polygynandrous mating system. In this species, the male cares for embryos in a specially developed brood pouch. During brooding, some embryos fail to develop. We experimentally mated males with either one or two females while keeping brood size similar. We found that broods of singly mated males showed significantly lower embryo survival than those of doubly mated males. Furthermore, larger broods showed relatively lower levels of embryo survivorship independent of number of mates. We conclude that embryo survival is affected by postcopulatory processes that appear to result in higher fitness of multiply mated males. We discuss our results in the light of parental care, sibling competition, genetic benefits, and kin selection. Key words: brood reduction, paternal care, polygyny, postcopulatory sexual selection, progeny diversity, Syngnathidae.

  • 39.
    Sagebakken, Gry
    et al.
    Univ Gothenburg, Dept Biol & Environm Sci, Gothenburg, Sweden..
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Kvarnemo, Charlotta
    Univ Gothenburg, Dept Biol & Environm Sci, Gothenburg, Sweden..
    Costs and Benefits to Pregnant Male Pipefish Caring for Broods of Different Sizes2016In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 5, article id e0156484Article in journal (Refereed)
    Abstract [en]

    Trade-offs between brood size and offspring size, offspring survival, parental condition or parental survival are classic assumptions in life history biology. A reduction in brood size may lessen these costs of care, but offspring mortality can also result in an energetic gain, if parents are able to utilize the nutrients from the demised young. Males of the broad-nosed pipefish (Syngnathus typhle) care for the offspring by brooding embryos in a brood pouch. Brooding males can absorb nutrients that emanate from embryos, and there is often a reduction in offspring number over the brooding period. In this study, using two experimentally determined brood sizes (partially and fully filled brood pouches), we found that full broods resulted in larger number of developing offspring, despite significantly higher absolute and relative embryo mortality, compared to partial broods. Male survival was also affected by brood size, with males caring for full broods having poorer survival, an effect that together with the reduced embryo survival was found to negate the benefit of large broods. We found that embryo mortality was lower when the brooding males were in good initial condition, that embryos in broods with low embryo mortality weighed more, and surprisingly, that males in higher initial condition had embryos of lower weight. Brood size, however, did not affect embryo weight. Male final condition, but not initial condition, correlated with higher male survival. Taken together, our results show costs and benefits of caring for large brood sizes, where the numerical benefits come with costs in terms of both embryo survival and survival of the brooding father, effects that are often mediated via male condition.

  • 40. Sagebakken, Gry
    et al.
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Mobley, Kenyon B.
    Braga Goncalves, Ines
    Kvarnemo, Charlotta
    Brooding fathers, not siblings, take up nutrients from embryos2010In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 277, no 1683, p. 971-977Article in journal (Refereed)
    Abstract [en]

    It is well known that many animals with placenta-like structures provide their embryos with nutrients and oxygen. However, we demonstrate here that nutrients can pass the other way, from embryos to the parent. The study was done on a pipefish, Syngnathus typhle, in which males brood fertilized eggs in a brood pouch for several weeks. Earlier research has found a reduction of embryo numbers during the brooding period, but the fate of the nutrients from these 'reduced' embryos has been unknown. In this study, we considered whether (i) the brooding male absorbs the nutrients, (ii) siblings absorb them, or (iii) a combination of both. Males were mated to two sets of females, one of which had radioactively labelled eggs (using C-14-labelled amino acids), such that approximately half the eggs in the brood pouch were labelled. This allowed us to trace nutrient uptake from these embryos. We detected that C-14-labelled amino acids were transferred to the male brood pouch, liver and muscle tissue. However, we did not detect any significant C-14-labelled amino-acid absorption by the non-labelled half-siblings in the brood pouch. Thus, we show, to our knowledge, for the first time, that males absorb nutrients derived from embryos through their paternal brood pouch.

  • 41.
    Sagebakken, Gry
    et al.
    Univ Gothenburg, Dept Biol & Environm Sci, Gothenburg, Sweden..
    Kvarnemo, Charlotta
    Univ Gothenburg, Dept Biol & Environm Sci, Gothenburg, Sweden..
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Nutritional state - a survival kit for brooding pipefish fathers2017In: Biological Journal of the Linnean Society, ISSN 0024-4066, E-ISSN 1095-8312, Vol. 121, no 2, p. 312-318Article in journal (Refereed)
    Abstract [en]

    A parent's nutritional state may influence its ability to provide care to offspring and ability to handle infections. In the broad-nosed pipefish, Syngnathus typhle, males care for their offspring by brooding the developing embryos in a brood pouch, providing nutrients and oxygen, resembling a pregnancy. Here, we demonstrate that the nutritional state of pregnant males covaries with their own survival during a selective event. Brooding males surviving a Vibrio sp. infection were in a significantly better nutritional state, as estimated by their hepatosomatic index. Furthermore, a higher nutritional state of the brooding male correlated with a lower embryo mortality, while feeding treatment (low vs. high) had no effect on male survival, nutritional state or embryo mortality. Finally, males brooding heavier embryos also showed a lower embryo mortality. This may reflect a maternal effect (if large eggs result in higher embryo survival), a paternal effect (if higher provisioning of male care promotes both embryo growth and survival), or a combination thereof (males caring more for large embryos). The results demonstrate the importance of a good nutritional state for a caring parent when their immunity is challenged.

  • 42. Sogabe, A.
    et al.
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal Ecology.
    The ovarian structure and mode of egg production in two polygamous pipefishes: a link to mating pattern2011In: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 78, no 6, p. 1833-1846Article in journal (Refereed)
    Abstract [en]

    In this study, the ovarian structure and mode of egg production were examined in two pipefishes, the broad-nosed pipefish Syngnathus typhle and the straight-nosed pipefish Nerophis ophidion, which show different types of polygamous mating patterns. Syngnathus typhle showed an ovary with one germinal ridge and asynchronous egg production, corresponding to previous findings in other polygamous Syngnathus pipefishes. In contrast, the ovary of N. ophidion had two germinal ridges and eggs were produced synchronously in groups, similar to what has been observed in monogamous syngnathids. The egg production of N. ophidion, however, is clearly distinguished from that of monogamous syngnathids by the additional egg production after an ovulation. It is suggested that the differences in female mating strategies result from the difference in egg production process and that this is related to the difference in mating pattern between these two polygamous species.

  • 43.
    Svensson, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Reproductive Costs in two Sex-Role Reversed Pipefish Species (Syngnathidae)1988In: Journal of Animal Ecology, ISSN 0021-8790, E-ISSN 1365-2656, Vol. 57, no 3, p. 929-942Article in journal (Refereed)
    Abstract [en]

    (1) In two species of pipefish (Syngnathidae) the reproductive costs of the two sexes were compared to see how they might influence patterns of sex-role reversal. (2) In Syngnathus typhle, males brood their offspring in a brood pouch, providing them with nutrients and oxygen. Sexes are monomorphic. Males faced reproductive costs in terms of a lower food intake compared with females. Also, males grew more slowly than females, which yields a cost to future reproduction, as larger males could brood more offspring. No sexual difference in predation risk was found. The over-winter survival of males was probably lowered because intestinal fat deposition was delayed as a result of their reproductive efforts. (3) In Nerophis ophidion, males brood their offspring attached to their ventral body side, and provide them with nutrients and oxygen. Sexes are dimorphic, females being larger and brighter in colour. Males suffered an increased predation risk when brooding. No indications of energetic costs were found, e.g. through a lowered food intake or a slower growth rate. (4) Reproductive costs differed in the two species, probably reflecting differences in brood care. However, in both species the limiting sex, males, faced higher reproductive costs than females, as would be expected in sex-role reversed animals.

  • 44.
    Tsuboi, Masahito
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Lim, A. C. O.
    Univ Malaya, Inst Biol Sci, Fac Sci, Kuala Lumpur, Malaysia.; Save Our Seahorses Malaysia, Petaling Jaya, Selangor, Malaysia..
    Ooi, B. L.
    Univ Malaya, Inst Biol Sci, Fac Sci, Kuala Lumpur, Malaysia.; Save Our Seahorses Malaysia, Petaling Jaya, Selangor, Malaysia..
    Yip, M. Y.
    Univ Malaya, Inst Biol Sci, Fac Sci, Kuala Lumpur, Malaysia.; Save Our Seahorses Malaysia, Petaling Jaya, Selangor, Malaysia..
    Chong, V. C.
    Univ Malaya, Inst Biol Sci, Fac Sci, Kuala Lumpur, Malaysia.; Univ Malaya, Inst Ocean & Earth Sci, Kuala Lumpur, Malaysia..
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Kolm, N.
    Stockholm Univ, Dept Zool Ethol, Stockholm, Sweden..
    Brain size evolution in pipefishes and seahorses: the role of feeding ecology, life history and sexual selection2017In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 30, no 1, p. 150-160Article in journal (Refereed)
    Abstract [en]

    Brain size varies greatly at all taxonomic levels. Feeding ecology, life history and sexual selection have been proposed as key components in generating contemporary diversity in brain size across vertebrates. Analyses of brain size evolution have, however, been limited to lineages where males predominantly compete for mating and females choose mates. Here, we present the first original data set of brain sizes in pipefishes and seahorses (Syngnathidae) a group in which intense female mating competition occurs in many species. After controlling for the effect of shared ancestry and overall body size, brain size was positively correlated with relative snout length. Moreover, we found that females, on average, had 4.3% heavier brains than males and that polyandrous species demonstrated more pronounced (11.7%) female-biased brain size dimorphism. Our results suggest that adaptations for feeding on mobile prey items and sexual selection in females are important factors in brain size evolution of pipefishes and seahorses. Most importantly, our study supports the idea that sexual selection plays a major role in brain size evolution, regardless of on which sex sexual selection acts stronger.

  • 45.
    Tsuboi, Masahito
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Shoji, Jun
    Hiroshima Univ, Ctr Field Sci Seto Inland Sea, 5-8-1 Minatomachi, Takehara City, Hiroshima 7250024, Japan..
    Sogabe, Atsushi
    Hirosaki Univ, Fac Agr & Life Sci, Dept Biol, 1-1 Bunkyo Cho, Hirosaki, Aomori 0368560, Japan..
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Kolm, Niclas
    Stockholm Univ, Dept Zool Ethol, Svante Arrhenius vag 18B, SE-10691 Stockholm, Sweden..
    Within species support for the expensive tissue hypothesis: a negative association between brain size and visceral fat storage in females of the Pacific seaweed pipefish2016In: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 6, no 3, p. 647-655Article in journal (Refereed)
    Abstract [en]

    The brain is one of the most energetically expensive organs in the vertebrate body. Consequently, the high cost of brain development and maintenance is predicted to constrain adaptive brain size evolution (the expensive tissue hypothesis, ETH). Here, we test the ETH in a teleost fish with predominant female mating competition (reversed sex roles) and male pregnancy, the pacific seaweed pipefish Syngnathus schlegeli. The relative size of the brain and other energetically expensive organs (kidney, liver, heart, gut, visceral fat, and ovary/testis) was compared among three groups: pregnant males, nonpregnant males and egg producing females. Brood size in pregnant males was unrelated to brain size or the size of any other organ, whereas positive relationships were found between ovary size, kidney size, and liver size in females. Moreover, we found that the size of energetically expensive organs (brain, heart, gut, kidney, and liver) as well as the amount of visceral fat did not differ between pregnant and nonpregnant males. However, we found marked differences in relative size of the expensive organs between sexes. Females had larger liver and kidney than males, whereas males stored more visceral fat than females. Furthermore, in females we found a negative correlation between brain size and the amount of visceral fat, whereas in males, a positive trend between brain size and both liver and heart size was found. These results suggest that, while the majority of variation in the size of various expensive organs in this species likely reflects that individuals in good condition can afford to allocate resources to several organs, the cost of the expensive brain was visible in the visceral fat content of females, possibly due to the high costs associated with female egg production.

  • 46.
    Vincent, Amanda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Zoology.
    Operational sex ratios and behavioral sex differences in a pipefish population1994In: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 34, p. 435-442Article in journal (Refereed)
    Abstract [en]

    In the pipefish Syngnathus typhle, only males brood embryos in specially developed brood pouches, supplying oxygen and nutrients. Laboratory studies have shown that this elaborate paternal care has led to sex-role reversal in this species: males limit female reproductive rate, females are the primary competitors for mates and males exercise greater selectivity in accepting mates. In the first field study of this pipefish, we describe mating behaviour in the wild and test the hypothesis that temporal variations in the operational sex ratio (OSR) determine sex differences in mating behaviour. Our study comprised two reproductive seasons of two sequential mating periods each, the latter separated by a lengthy interval of male brooding. During mating periods, females displayed to all males without wandering and males moved about searching for females, without reacting to all females. The OSR was least female-biased (or even male-biased) at the onset of the breeding season, when most pipefish were simultaneously available to mate, but became strikingly female-biased as males' pouches were filled. The OSR remained substantially female-biased during the second mating period, because few males became available to remate at any one time. As hypothesised, female-biased OSRs resulted in more female-female meetings. As well, females were above the eelgrass more often than brooding males, thus exposing themselves to conspecifics and/or predators. In the second year, males arrived earlier than females on the breeding site and male pregnancies were shorter, because of higher water temperatures, so rematings occurred earlier. Males met more often during that year than the previous one, but male competitive interactions were still not observed. The field results support laboratory studies and demonstrate that behaviours associated with female-female competition are more prominent when the OSR is more female-biased.

  • 47. Vincent, Amanda
    et al.
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Rosenqvist, Gunilla
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Pipefishes and seahorses: are they all sex-role reversed?1992In: Trends in Ecology & Evolution, ISSN 0169-5347, E-ISSN 1872-8383, Vol. 7, no 7, p. 237-241Article in journal (Refereed)
    Abstract [en]

    The male pregnancy of pipefishes and seahorses has led to the inference that females compete most intensely for access to mates, because males limit female reproduction. However, recent work has shown that in different species either sex may be the predominant competitor for mates. In this family, there is an apparent association between the mating pattern and the sex roles: polygamous species show reversed sex roles whereas monogamous species exhibit 'conventional' sex roles. These studies emphasize that sex role reversal is not synonymous with male parental care.

  • 48. Vincent, Amanda C.J.
    et al.
    Berglund, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
    Reproductive ecology of five pipefish species in one eelgrass meadow1995In: Environmental Biology of Fishes, ISSN 0378-1909, E-ISSN 1573-5133, Vol. 44, no 4, p. 347-361Article in journal (Other academic)
    Abstract [en]

    Synopsis Pipefishes have rarely been watched in the wild and have never before been followed in their common seagrass habitats. This study explores the reproductive ecology of five species of pipefishes living in a Swedish eelgrass meadow during parts of four breeding seasons, tagging four of the species. Pipefish are remarkable for their specialised paternal care: only males aerate, osmoregulate and nourish the developing embryos. Two of the species (Entelurus aequoreus andNerophis ophidion) have simple ventral gluing of eggs on the trunk while three species (Syngnathus acus, S. rostellatus andS. typhle) have fully enclosed brood pouches on their tails. Males of the former species receive eggs from one female while males of the genusSyngnathus receive partial clutches from several females. Sex ratios of adults on the site differed from equal to male-biased to female-biased, according to species.S. typhle were most numerous and were resighted most often. They were present throughout the breeding season whereas there were temporal shifts in the presence of the other species on the meadow and in some sex ratios. Most species occurred in the deeper, denser part of the meadow but there was some habitat separation by species and sex. All species tended to stay low in the eelgrass, primarily coming up above the eelgrass to display and mate. No species showed site fidelity either to a home range or to the meadow, withE. aequoreus adults spending least time on the meadow. Sexual size dimorphism differed: males were larger inS. rostellatus, the same size inS acus and smaller in the other species. Although the species overlap in habitat requirements and breeding season, the only observed interspecific interactions were abortive courtships betweenSyngnathus species.

  • 49. Wilson, A
    et al.
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology. Zooekologi.
    Vincent, A
    Meyer, A
    The dynamics of male brooding, mating patterns, and sex roles in pipefishes and seahorses (family Syngnathidae)2003In: Evolution, Vol. 57, p. 1374-1386Article in journal (Refereed)
  • 50. Wilson, A.B.
    et al.
    Vincent, A.
    Ahnesjö, Ingrid
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology, Animal Ecology.
    Meyer, A.
    Male pregnancy in seahorses and pipefishes (Family Syngnathidae): Rapid diversification of paternal brood pouch morphology inferred from a molcular phylogeny2001In: The Journal of Heredity, Vol. 92, no 2, p. 159-166Article in journal (Refereed)
1 - 50 of 50
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