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  • 51. Cunha, Mário
    et al.
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Monteiro, Nuno
    Female ornaments signal own and offspring quality in a sex-role-reversed fish with extreme male parental care2017Ingår i: Marine Ecolocy, ISSN 0173-9565, E-ISSN 1439-0485, Vol. 38, artikel-id e12461Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Although female ornaments have been described in many taxa, the full spectrum of information conveyed by such traits together with the potential male fitness benefits are far from fully understood. Here, we used a sex-role-reversed species, the black-striped pipefish, Syngnathus abaster, where females are the ornamented sex and intensively compete for mates who present an extreme form of paternal care (male pregnancy). We investigated what information is conveyed by female traits and if males are using it during mate choice. We further assessed which traits would reflect offspring quality at birth. We found that although body length generally portrays information on female reproductive potential (gonadosomatic index and oocyte diameter),it does so indirectly. Different aspects of the female traits, such as stripe width and trunk broadness, were found to be better direct indicators. When size is kept constant, males prefer females with wider stripes. Moreover, stripe coloration was found to reflect offspring quality as darker-striped females produced larger newborns. Our observations suggest that in a species with exclusive paternal care, independently from the male’s direct investment in reproduction, female contribution decisively impacts male fitness. Thus, at least in sex-role-reversed species such as the black striped pipefish, female ornaments can be selected in an analogous way to those of males in species with conventional sex roles (i.e. by mate choice).

  • 52. Fitzpatrick, Susan
    et al.
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Rosenqvist, Gunilla
    Ornaments or offspring: costs to reproductive success restrict sexual selection processes1995Ingår i: Biological Journal of the Linnean Society, ISSN 0024-4066, E-ISSN 1095-8312, Vol. 55, nr 3, s. 251-260Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    If, in their partner choice, males seek direct benefits (fecund females), the result will be selection for traits indicating female quality rather than for arbitrary (Fisherian) traits. However, the costs of developing and maintaining the sexually selected traits (ornaments) may reduce the resources available to the female for allocation to reproduction and hence result in lower reproductive success per brood. This hitherto unrecognized fecundity cost of sexually selected traits will constrain both the potency of sexual selection mechanisms and the degree of elaboration of sexually selected traits in females, and can also apply to males which invest in their offspring: sexual selection becomes self-limiting. The fitness implications of these costs are examined for both sexes in a variety of mating and parental care patterns. Sexual selection acting on both sexes may lead to either dimorphism or monomorphism, the latter being the case when the quality indicators chosen by both sexes coincide. Ways of evasion or reduction of these reproductive costs of allocations to sexually selected traits include using different resource components for the ornament and for reproduction, or partitioning the two allocations in time. (C) 1995 The Linnean Society of London

  • 53. Forsgren, Elisabet
    et al.
    Reynolds, John D.
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Zoologiska institutionen.
    Behavioural ecology of reproduction2002Ingår i: Handbook of Fish Biology and Fisheries: Vol. 1, Fish biology / [ed] Paul J. B. Hart and John D. Reynolds, Malden: Blackwell Science , 2002, s. 225-250Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 54.
    Fuller, Rebecca
    et al.
    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.
    Behavioral responses of a sex-role reversed pipefish to a gradient of perceived predation risk1996Ingår i: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 7, nr 1, s. 69-75Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Conspicuous behaviors such as courtship and mating often make animals susceptible to predation. When perceiving themselves at an elevated level of risk, animals frequently reduce conspicuous behaviors in trade-off for a decrease in probability of being preyed upon. In the present study, we used two experiments to examine the effect of perceived predation risk from cod (Gadus morhua) on nonreproductive and reproductive behaviors in the sex-role reversed pipefish (Syngnathus typhle). In the first experiment, no differences due to predation risk were detected in the nonreproductive behaviors of either males or females. In the second experiment, predation risk had significant effects on reproductive behaviors. Pipefish were allowed to court and copulate at four different predation levels. We created predation levels differing in perceived predation risk by controlling the number of sensory modes through which pipefish could detect the presence of a cod. As predation risk increased, pipefish copulated and courted less frequently, swam alone (displayed and searched for conspecifics) less often, and waited longer before commencing courtship. These changes in behavior minimized the amount of time spent above the eelgrass and presumably reduced conspicuousness to visual predators. Pipefish also copulated after a smaller amount of courtship as predation risk increased, indicating that they may trade information concerning mate quality for a reduction ill predation risk. No differences were found in any response variable between males and females. The role of operational sex ratios and intersexual competition in determining which sex assumes greater costs in mate acquisition is questioned.

  • 55.
    Gunnarsson, Karl
    et al.
    Dept. of Botany, Stockholm University.
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    The brown alga Fucus radicans suffers heavy grazing by the isopod Idotea baltica2012Ingår i: Marine Biology Research, ISSN 1745-1000, E-ISSN 1745-1019, Vol. 8, nr 1, s. 87-89Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In 2005, a perennial brown alga in the Baltic Sea was recognized as a species on its own and named Fucus radicans (Bergström & Kautsky). This fucoid forms belts like does bladderwrack, Fucus vesiculosus L., its closest relative. These seaweeds are inhabited by many small animals, for example the isopod Idotea baltica (Pallas, 1772). Along the Swedish coasts of the Baltic Sea, F. radicans is found primarily in the northern half, i.e. the Gulf of Bothnia. I. baltica is common in the seaweeds of the southern half of the Baltic Sea, the Baltic proper, but is uncommon further north in the Bothnian Sea and nonexistent in the northernmost Bay of Bothnia. I. baltica is well able to graze down seaweeds in an area. In a field experiment, we here show that I. baltica, given a choice between the two algae species, prefers to graze on F. radicans rather than on F. vesiculosus. This may be one of the most important factors restricting F. radicans to the northern areas of the Baltic, where I. baltica is uncommon.

  • 56. 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.

  • 57. 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.

  • 58. Jones, Adam G.
    et al.
    Rosenqvist, Gunilla
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Arnold, Stevan J.
    Avise, John C.
    The Bateman gradient and the cause of sexual selection in a sex-role-reversed pipefish2000Ingår i: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 267, nr 1444, s. 677-680Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    As a conspicuous evolutionary mechanism, sexual selection has received much attention from theorists and empiricists. Although the importance of the mating system to sexual selection has long been appreciated, the precise relationship remains obscure. In a classic experimental study based on parentage assessment using visible genetic markers, more than 50 years ago A. J. Bateman proposed that the cause of sexual selection in Drosophila is ‘the stronger correlation, in males (relative to females), between number of mates and fertility (number of progeny)’. Half a century later, molecular genetic techniques for assigning parentage now permit mirror–image experimental tests of the ‘Bateman gradient’ using sex–role–reversed species. Here we show that, in the male–pregnant pipefish Syngnathus typhle, females exhibit a stronger positive association between number of mates and fertility than do males and that this relationship responds in the predicted fashion to changes in the adult sex ratio. These findings give empirical support to the idea that the relationship between mating success and number of progeny, as characterized by the Bateman gradient, is a central feature of the genetic mating system affecting the strength and direction of sexual selection.

  • 59. Jones, Adam G.
    et al.
    Rosenqvist, Gunilla
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Avise, John C.
    Clustered microsatellite mutations in the pipefish Syngnathus typhle1999Ingår i: Genetics, ISSN 0016-6731, E-ISSN 1943-2631, Vol. 152, nr 3, s. 1057-1063Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Clustered mutations are copies of a mutant allele that enter a population's gene pool together due to replication fi om a premeiotic germline mutation and distribution to multiple successful gametes of an individual. Although the phenomenon has been studied in Drosophila and noted in a few other species, the topic has received scant attention despite claims of being of major importance to population genetics theor). Here we capitalize upon the reproductive biology of male-pregnant pipefishes to document the occurrence of clustered microsatellite mutations and to estimate their rates and patterns from family data. Among a total of 3195 embryos genetically screened from 110 families, 40% of the 35 detected de novo mutant alleles resided in documented mutational clusters. Most of the microsatellite mutations appeared to involve small-integer changes ill repeat copy number, and they arose in approximately equal frequency in paternal and maternal germlines. These findings extend observations on clustered mutations to another organismal group and motivate a broader critique of the mutation cluster phenomenon. They also carry implications for the evolution of microsatellites with respect to mutational models and homoplasty among alleles.

  • 60. Jones, Adam G.
    et al.
    Rosenqvist, Gunilla
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Avise, John C.
    Mate quality influences multiple maternity in the sex-role-reversed pipefish Syngnathus typhle2000Ingår i: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 90, nr 2, s. 321-326Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the pipefish Syngnathus typhle, pregnant males provide all parental care. Females are able to produce more eggs than males can brood, and consequently females compete more intensely for mates than do males, a phenomenon defined as sex-role reversal. As the genetic mating system influences the operation of sexual selection, we investigate variation in one phenotypic component of mate quality, female body size, as a possible proximate influence on mating system variation in S. typhle. Breeding trials were employed, each consisting of a single receptive male with four adult females. In each replicate, a focal male was paired either with a set of small or with a set of large females. Males were allowed to mate freely, and after several weeks of brood development, maternity of the progeny was resolved using three microsatellite loci. Males with access either to small or to large females successfully mated with a mean of 2.1 or 1.3 females, respectively, a significant difference. Results indicate that variation in female size can affect the mating system and thereby influence sexual selection in pipefish. Thus, the high rate of multiple mating by S. typhle males in the wild may be explained in part by the extensive size variation in naturally occurring, sexually mature females.

  • 61. Jones, Adam G.
    et al.
    Rosenqvist, Gunilla
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Avise, John C.
    The genetic mating system of a sex-role-reversed pipefish (Syngnathus typhle): a molecular inquiry1999Ingår i: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 46, nr 5, s. 357-365Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the pipefish Syngnathus typhle as in other species of Syngnathidae, developing embryos are reared on the male's ventral surface. Although much laboratory research has been directed toward understanding sexual selection in this sex-role-reversed species, few studies have addressed the mating behavior of S. typhle in the wild, and none has capitalized upon the power of molecular genetic assays. Here we present the first direct assessment of the genetic mating system of S. typhle in nature. Novel microsatellite loci were cloned and characterized from this species, and employed to assay entire broods from 30 pregnant, field-captured males. Genetic analysis of 1340 embryos revealed that 1-6 females (mean = 3.1) contributed to each brooded clutch, the highest rate of multiple maternity yet documented in any pipefish. Evidence of multiple mating by females was also detected. Thus, this population of S. typhle displays a polygynandrous mating system, a finding consistent with previous field and laboratory observations. Our results, considered together with similar studies of other syngnathid species, provide preliminary support for the hypothesis that the genetic mating system is related to the evolution of sexual dimorphism in the fish family Syngnathidae.

  • 62. Jones, Adam G.
    et al.
    Rosenqvist, Gunilla
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Avise, John C.
    The measurement of sexual selection using Bateman's principles: An experimental test in the sex-role-reversed pipefish Syngnathus typhle2005Ingår i: Integrative and Comparative Biology, ISSN 1540-7063, E-ISSN 1557-7023, Vol. 45, nr 5, s. 874-884Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Angus J. Bateman's classic study of sexual selection in Drosophila melanogaster has had a major influence on the development of sexual selection theory. In some ways, Bateman's study has served a catalytic role by stimulating debate on sex roles, sexual conflict and other topics in sexual selection. However, there is still considerable disagreement regarding whether or not "Bateman's principles" are helpful in the study of sexual selection. Here, we test the idea that Bateman's principles provide the basis for a useful method to quantify and compare mating systems. In this study, we focus on the sex-role-reversed pipefish Syngnathus typhle as a model system to study the measurement of sexual selection. We set up artificial breeding assemblages of pipefish in the laboratory and used microsatellite markers to resolve parentage. Three different sex-ratio treatments (female-biased, even and male-biased) were used to manipulate the expected intensity of sexual selection. Measures of the mating system based on Bateman's principles were calculated and compared to the expected changes in the intensity of sexual selection. We also compare the results of this study to the results of a similar study of Bateman's principles in the rough-skinned newt, a species with conventional sex roles. The results of this experiment show that measures of the mating system based on Bateman's principles do accurately capture the relative intensities of sexual selection in the different treatments and species. Thus, widespread use of Bateman's principles to quantify mating systems in nature would facilitate comparative studies of sexual selection and mating system evolution.

  • 63.
    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.

  • 64. Kolm, Niclas
    et al.
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, 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, s. 910-914Artikel i tidskrift (Refereegranskat)
  • 65.
    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.

  • 66.
    Lindqvist, Charlotte
    et al.
    Högskolan på Gotland, Avdelningen för Biologi.
    Sundin, Josefin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Rosenqvist, Gunilla
    Högskolan på Gotland, Institutionen för kultur, energi och miljö.
    Male broad-nosed pipefish Syngnathus typhle do not locate females by smell2011Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 78, nr 6, s. 1861-1867Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Broad-nosed pipefish Syngnathus typhle were used to investigate whether males used scent in their search for mates. When the males in an experiment had access to olfactory cues only, they did not locate females better than they located males. Thus, S. typhle, was less successful in mate search when visual cues were absent.

  • 67. Mayer, Ian
    et al.
    Rosenqvist, Gunilla
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Borg, Bertil
    Ahnesjö, Ingrid
    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.
    Schulz, Rüdiger W.
    Plasma-levels of sex steroids in 3 species of pipefish (Syngnathidae)1993Ingår i: Canadian Journal of Zoology, ISSN 0008-4301, E-ISSN 1480-3283, Vol. 71, nr 9, s. 1903-1907Artikel i tidskrift (Refereegranskat)
    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.

  • 68.
    Mobley, Kenyon
    et al.
    Department of Ecology and Environmental Science, Umeå university.
    Kvarnemo, Charlotta
    Department of Zoology, Göteborg University.
    Ahnesjö, Ingrid
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Partridge, Charlyn
    Department of Biology, Texas A&M University, USA.
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    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 pipefish2011Ingår i: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 65, nr 6, s. 1169-1177Artikel i tidskrift (Refereegranskat)
    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.

  • 69. Monteiro, N.M.
    et al.
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Vieira, M.N.
    Almada, V.C.
    Reproductive migrations of the sex role reversed pipefish Nerophis lumbriciformis (Pisces;Syngnathidae)2006Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 69, nr 1, s. 66-74Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Using an individual identification technique, a population of worm pipefish Nerophis lumbriciformis was followed during 19 months, in order to determine the exact use of the intertidal and, considering the specific movement patterns of males and females, the mating system exhibited by this population. Field observations showed that the number of adults increased during the breeding season, with males arriving 1 month earlier than females. Furthermore, males and females presented distinct permanence periods, showing that the intertidal is used as a mating arena. It was also observed that both male and female worm pipefish mated repeatedly over the span of a reproductive season, but females exhibited shorter remating intervals. Also, females stayed for longer periods on the mating grounds, the intertidal zone, whereas males typically left for the subtidal after mating, usually returning within 2 months. These inter-sexual differences in the occupation of the intertidal suggest that females breed with different males but also that males accept eggs from various females since, on their return, a new group of mating partners was now available. Thus, N. lumbriciformis might be considered polygynandric. It is a clearly dimorphic species in spite of the observed polygynandry, suggesting that differences in remating intervals may be influential in determining the strength of sexual selection along with what may be expected from the polygynandrous mating system alone.

  • 70. Partridge, Charlyn
    et al.
    Ahnesjö, Ingrid
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Kvarnemo, Charlotta
    Mobley, B
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Jones, G
    The effect of perceived female parasite load on post-copulatory male choice in a sex-role-reversed pipefish2009Ingår i: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 63, nr 3, s. 345-354Artikel i tidskrift (Refereegranskat)
    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.

  • 71.
    Rosenqvist, Gunilla
    et al.
    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.
    Is female sexual-behavior a neglected topic?1992Ingår i: Trends in Ecology & Evolution, ISSN 0169-5347, E-ISSN 1872-8383, Vol. 7, nr 6, s. 174-176Artikel i tidskrift (Refereegranskat)
  • 72.
    Rosenqvist, Gunilla
    et al.
    Högskolan på Gotland, Institutionen för kultur, energi och miljö.
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Sexual signals and mating patterns in Syngnathidae2011Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 78, nr 6, s. 1647-1661Artikel i tidskrift (Refereegranskat)
    Abstract [sv]

    Man graviditet i familjen Syngnathidae (pipefishes, sjöhästar och seadragons) predisponerar hanar att begränsa kvinnliga reproduktiva framgång, sexuell selektion kan då arbeta mer på kvinnor och kvinnliga sexuella signaler kan utvecklas (sex-roll vändning). En förvirrande mängd kvinnliga signaler har utvecklats i Syngnathids, t.ex. hudveck, stor kroppsstorlek, färgning, märkning på kroppen och utarbeta uppvaktning. Dessa kvinnliga sexuella signaler verkar inte kvantitativt eller kvalitativt skiljer sig från dem som utvecklas hos män i arter med konventionella könsroller där män ger honor eller avkomma med direkta fördelar. I flera syngnathid arter, män också utvecklas ornament, kvinnor är kräsna förutom att vara konkurrenskraftiga och män tävlar samt välja partner. Således könsrollerna bildar ett kontinuum, som spänner från konventionella till återförda inom denna grupp av fiskar. Fall presenteras här tyder på att en starkare sexuell selektion på honor kan vara mest extrem i arter som visar klassiska polyandri (en hane parar sig med flera honor, som många arter där hanar ruva sina ägg på bålen), intermediära i polygynandrous arter (män och kvinnor både parar sig med mer än en partner, som i många arter där hanar ruva sina ägg på svansen) och minst extrema, till och med uppvisar konventionella könsroller i monogama arter (en hane parar enbart med en kvinna, som i många sjöhästar och tropiska pipefishes). Samtidigt måste försiktighet iakttas innan enhälligt upprättandet detta mönster: för det första är sambandet mellan parningen mönster, styrka sexuell selektion, könsroller och prydnad uttryck långt ifrån enkel och okomplicerad, dels kunskap om de faktiska morfologi, ekologi och beteende de flesta syngnathid arter är knapphändig. I grund och botten bara ett fåtal Nerophis, Syngnathus och arter Hippocampus har studerats i detalj. Det är dock känt att denna grupp av fiskar uppvisar en anmärkningsvärd variation i könsroller och ornamentik, vilket gör dem till en idealisk grupp för studiet av parningen mönster, sexuell selektion och sexuellt utvalda signaler.

  • 73. Roth, O.
    et al.
    Sundin, Josefin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Wegner, K. M.
    Rosenqvist, G.
    Male mate choice relies on major histocompatibility complex class I in a sex-role-reversed pipefish2014Ingår i: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 27, nr 5, s. 929-938Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mate choice for compatible genes is often based on genes of the major histocompatibility complex (MHC). Although MHC-based mate choice is commonly observed in female choice, male mate choice remains elusive. In particular, if males have intense paternal care and are thus the choosing sex, male choice for females with dissimilar MHC can be expected. Here, we investigated whether male mate choice relies on MHC class I genes in the sex-role reversed pipefish Syngnathus typhle. In a mate choice experiment, we determined the relative importance of visual and olfactory cues by manipulating visibility and olfaction. We found that pipefish males chose females that maximize sequence-based amino acid distance between MHC class I genotypes in the offspring when olfactory cues were present. Under visual cues, large females were chosen, but in the absence of visual cues, the choice pattern was reversed. The use of sex-role reversed species thus revealed that sexual selection can lead to the evolution of male mate choice for MHC class I genes.

  • 74.
    Sandvik, Maria
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Rosenqvist, Gunilla
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Male and female mate choice affects offspring quality in a sex-role-reversed pipefish2000Ingår i: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 267, nr 1458, s. 2151-2155Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Where both sexes invest substantially in offspring, both females and males should discriminate between potential partners when choosing mates. The degree of choosiness should relate to the costs of choice and to the potential benefits to be gained. We measured offspring quality from experimentally staged matings with preferred and non–preferred partners in a sex–role–reversed pipefish, Syngnathus typhle L. Here, a substantial male investment in offspring results in a lower potential reproductive rate in males than in females, and access to males limits female reproductive success rather than vice versa. Thus, males are choosier than females and females compete more intensely over mates than do males. Broods from preferred matings were superior at escaping predation, when either males or females were allowed to choose a partner. However, only ‘choosing’ females benefited in terms of faster–growing offspring. Our results have important implications for mate–choice research: here we show that even the more competitive and less choosy sex may contribute significantly to sexual selection through mate choice.

  • 75.
    Sundin, Josefin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi. Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för neurovetenskap, Fysiologi.
    Aronsen, Tonje
    Norwegian Univ Sci & Technol, Dept Biol, Ctr Biodivers Dynam, Trondheim, Norway.; Norwegian Inst Nat Res NINA, Trondheim, Norway.
    Rosenqvist, Gunilla
    Norwegian Univ Sci & Technol, Dept Biol, Ctr Biodivers Dynam, Trondheim, Norway.
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Sex in murky waters: algal induced turbidity increases sexual selection in pipefish2017Ingår i: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 71, nr 5, artikel-id 78Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Algal induced turbidity has been shown to alter several important aspects of reproduction and sexual selection. However, while turbidity has been shown to negatively affect reproduction and sexually selected traits in some species, it may instead enhance reproductive success in others, implying that the impact of eutrophication is far more complex than originally believed. In this study, we aimed to provide more insight into these inconsistent findings. We used molecular tools to investigate the impact of algal turbidity on reproductive success and sexual selection on males in controlled laboratory experiments, allowing mate choice, mating competition and mate encounter rates to affect reproduction. As study species we used the broad-nosed pipefish, Syngnathus typhle, a species practicing male pregnancy and where we have previously shown that male mate choice is impaired by turbidity. Here, turbidity instead enhanced sexual selection on male size and mating success as well as reproductive success. Effects from mating competition and mate encounter rates may thus override effects from mate choice based on visual cues, producing an overall stronger sexual selection in turbid waters. Hence, seemingly inconsistent effects of turbidity on sexual selection may depend on which mechanisms of sexual selection that have been under study.

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  • 76.
    Sundin, Josefin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Rosenqvist, Gunilla
    Turbidity hampers mate choice in a pipefish2010Ingår i: Ethology, ISSN 0179-1613, E-ISSN 1439-0310, Vol. 116, nr 8, s. 713-721Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    European coastal waters have in recent years become more turbid as algal growth has increased, probably due to eutrophication, global warming and changes in fish communities. Turbidity reduces visibility, and such changes may in turn affect animal behaviour as well as evolutionary processes that are dependent on visual stimuli. In this study we experimentally manipulated water visibility and olfactory cues to investigate mate choice using the sex role-reversed broad-nosed pipefish Syngnathus typhle as our study organism. We show that males spent significantly longer time assessing females when they had access to full visual cues, compared to when visibility was reduced. Presence or absence of olfactory cues from females did not affect mate choice, suggesting that the possible use of smell could not make up for a reduction in visibility. This implies that mate choice is environmentally dependent and that an increased turbidity may affect processes of sexual selection through an impaired possibility for visually based mate choice.

  • 77.
    Sundin, Josefin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Jacobsson, Örjan
    Högskolan på Gotland, Institutionen för kultur, energi och miljö.
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Rosenqvist, Gunilla
    Högskolan på Gotland, Institutionen för kultur, energi och miljö. Norwegian University of Science and Technology, Trondheim.
    Straight-nosed pipefish Nerophis ophidion and broad-nosed pipefish Syngnathus typhle avoid eelgrass overgrown with filamentous algae2011Ingår i: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 78, nr 6, s. 1855-1860Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In a habitat choice experiment straight-nosed pipefish Nerophis ophidion and broad-nosed pipefishSyngnathus typhle avoided eelgrass Zostera marina covered with filamentous algae. Both juvenilesas well as brooding adult males of the two species clearly preferred to position themselves inZ. marina without growth of filamentous algae.

  • 78.
    Sundin, Josefin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Rosenqvist, Gunilla
    Biologiskt institutt, Norwegian University of Science and Technology, Trondheim.
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Altered oceanic pH impairs mating propensity in a pipefish2013Ingår i: Ethology, ISSN 0179-1613, E-ISSN 1439-0310, Vol. 119, nr 1, s. 86-93Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Anthropogenic disturbance is currently altering the environment of terrestrial as well as aquatic organisms. Those changes affect a variety of animal behaviours, which in turn may cause changes in species interactions, population dynamics and evolutionary processes. In marine ecosystems, nutrient enrichment may elevate pH, while it is reduced by carbon dioxide-induced ocean acidification. These two processes are not expected to balance one another but rather to affect the environment at different times and scales. We here show experimentally that an increase in water pH has a negative effect on mating propensity in the broad-nosed pipefish Syngnathus typhle, whereas lowered pH did not elicit the same detrimental effect. This study provides, to our knowledge, the first evidence that mating propensity is impaired by an increase in pH, suggesting that anthropogenic nutrient enrichment in aquatic ecosystems may change the processes of sexual selection and population dynamics solely on the basis of altered water pH.

  • 79.
    Sundin, Josefin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Rosenqvist, Gunilla
    Högskolan på Gotland.
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Hypoxia delays mating in the broad-nosed pipefish2015Ingår i: Marine Biology Research, ISSN 1745-1000, E-ISSN 1745-1019, Vol. 11, nr 7, s. 747-754Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Courtship is an important part of the reproductive process, ensuring reproductive compatibility and conveying individual quality. One factor in aquatic environments that has the potential to influence courtship behaviours and mating propensity is the level of dissolved oxygen. Furthermore, hypoxic areas are currently spreading due to anthropogenic disturbance, such as eutrophication. In marine environments, hypoxia often occurs in shallow coastal regions that are particularly important areas for reproduction. Here, we investigated how types of reproductive behaviour were affected by mild hypoxia using the well-studied broad-nosed pipefish, Syngnathus typhle. More precisely, we investigated the impact of acute hypoxia on the reproductive behaviour preceding mating, and on the probability of mating, as well as on the latency until these occurred. We found that the latency period to courting and copulation occurring was prolonged in the low-oxygen environment. However, the total time spent courting as well as the probability of mating was unaffected by hypoxia. Other types of reproductive behaviour found in this species, such as dancing, and the unique male pouch-flap behaviour, were also unaffected by the low-oxygen treatment. We conclude that although latency to courting and copulating was prolonged in the hypoxic environment, most reproductive behaviour investigated was unaffected by hypoxia. Thus, hypoxia commonly occurring in shallow coastal regions has the potential to delay certain components of reproduction, but overall the broad-nosed pipefish shows robustness to hypoxic conditions.

  • 80.
    Sundin, Josefin
    et al.
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för neurovetenskap, Fysiologi.
    Rosenqvist, Gunilla
    Myhren, Siri
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Algal Turbidity Hampers Ornament Perception, but Not Expression, in a Sex-Role-Reversed Pipefish2016Ingår i: Ethology, ISSN 0179-1613, E-ISSN 1439-0310, Vol. 122, nr 3, s. 215-225Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Sexual ornaments are used both in intra- and intersexual contexts, and these signals have evolved to function in the particular habitat the animal is adapted to. Habitat characteristics may, however, change rapidly due to anthropogenic effects, sometimes at rates too fast for many organisms to adaptively respond. In aquatic ecosystems, eutrophication is currently changing chemical as well as visual properties of the environment. Algae blooms increase water turbidity, and the reduction of water transparency thus has the potential to alter visual ornaments and their perception. However, results are not congruent. Rather, algae turbidity may decrease, increase, or leave ornaments unaffected. The effect seems to depend on exposure time, condition, population and species. Here, we found that the perception of sexual signals, but not their expression, was hampered by turbidity in the sex-role-reversed pipefish Nerophis ophidion. In a laboratory experiment we found that female sexual ornaments (i.e., blue color markings and a skinfold) and fecundity was unaffected by turbidity. Male adaptive mate choice for larger females with large ornament was, however, hampered under turbid conditions, whereas in clear water males choose larger, more ornamented females. Thus, we show that water turbidity had no effect on signal expression but did hamper ornament perception and consequently randomized mate choice.

  • 81.
    Vincent, Amanda
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Zoologiska institutionen.
    Ahnesjö, Ingrid
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Zoologiska institutionen.
    Berglund, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Zoologiska institutionen.
    Operational sex ratios and behavioral sex differences in a pipefish population1994Ingår i: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 34, s. 435-442Artikel i tidskrift (Refereegranskat)
    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.

  • 82. Vincent, Amanda
    et al.
    Ahnesjö, Ingrid
    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.
    Rosenqvist, Gunilla
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och evolution, Zooekologi.
    Pipefishes and seahorses: are they all sex-role reversed?1992Ingår i: Trends in Ecology & Evolution, ISSN 0169-5347, E-ISSN 1872-8383, Vol. 7, nr 7, s. 237-241Artikel i tidskrift (Refereegranskat)
    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.

  • 83. Vincent, Amanda C.J.
    et al.
    Berglund, Anders
    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.
    Reproductive ecology of five pipefish species in one eelgrass meadow1995Ingår i: Environmental Biology of Fishes, ISSN 0378-1909, E-ISSN 1573-5133, Vol. 44, nr 4, s. 347-361Artikel i tidskrift (Övrigt vetenskapligt)
    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.

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