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John E. Elliott - One of the best experts on this subject based on the ideXlab platform.
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Effects of halogenated contaminants on reproductive development in wild mink (Neovison vison) from locations in Canada
Ecotoxicology, 2018Co-Authors: John E. Elliott, David Anthony Kirk, Pamela A. Martin, Laurie K. Wilson, Gabriela Kardosi, Tana Mcdaniel, Kimberley D. Hughes, Barry D. Smith, Abde Miftah IdrissiAbstract:The concept of the Anthropocene, that humans are now re-engineering global ecosystems, is in part evidenced by the pervasive pollution by persistent organic pollutants (POPs). Certain POPs are hormone mimics and can disrupt endocrine and hence reproductive processes, shown mainly by laboratory studies with model species. There are, in contrast, fewer confirmations of such disruption from eco-epidemiological studies of wild mammals. Here we used the American mink ( Neovison vison ) as a sentinel species for such a study. Over the period 1998–2006, 161 mink carcasses were obtained from commercial trappers in the Canadian provinces of British Columbia and Ontario. Mink were aged, sexed, measured, and body condition assessed. Livers were analyzed either individually or pooled for organochlorine (OC) pesticides, polychlorinated biphenyls (PCBs), and subsets for polybrominated diphenyl ethers (PBDEs). We primarily addressed whether contaminants affected male reproductive development by measuring Baculum size and assessing the influences of age and body condition. We also considered the influence of spatial variation on relative exposure and size of Baculum. Statistical models separated by age class revealed that significant relationships between Baculum length or mass and juvenile mink were mostly positive, whereas for adults and first year mink they were mostly negative. A significant negative relationship for adult mink was determined between DDE and both Baculum length and mass. For juvenile mink we found significant positive relationships between ∑PCBs, DDE and ∑PBDEs with Baculum length. Our results provide some indication of negative effects of halogenated contaminants on male reproductive development in wild mink, and the most likely candidate chemical is the confirmed anti-androgenic compound, DDE, rather than PCBs or other compounds.
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reproductive and morphological condition of wild mink mustela vison and river otters lutra canadensis in relation to chlorinated hydrocarbon contamination
Environmental Health Perspectives, 1999Co-Authors: Lee E Harding, Megan L Harris, Craig R Stephen, John E. ElliottAbstract:We assessed chlorinated hydrocarbon contamination of mink and river otters on the Columbia and Fraser River systems of northwestern North America, in relation to morphological measures of condition. We obtained carcasses of mink and river otters from commercial trappers during the winters 1994-1995 and 1995-1996. Necropsies included evaluation of the following biological parameters: sex, body mass and length, age, thymus, heart, liver, lung, spleen, pancreas, kidney, gonad, omentum, adrenal gland and Baculum masses, Baculum length, and stomach contents. Livers were analyzed, individually or in pools, for residues of organochlorine (OC) pesticides, polychlorinated biphenyls (PCBs), dibenzo-p-dioxins, and dibenzofurans. Contaminant levels were relatively low compared to those documented in other North American populations, although they ranged higher than those detected during an earlier survey (1990-1992) of these regional populations. Body condition varied slightly among collection regions, but showed no relationship with contaminant burden. Mink from the upper Fraser River had less fat stores and also had some of the lowest OC contamination levels observed. Similarly, a few individuals with enlarged livers and kidneys had low contaminant levels. Although a few individual animals with gross abnormalities of reproductive systems did not show high levels of contamination, there was a significant negative correlation between total PCB concentrations (as Aroclor 1260) and Baculum length in juvenile mink (r = 0.707; p = 0.033; n = 8). The association of juvenile Baculum length with eventual reproductive success is unknown, but further characterization of reproductive organ morphology and relationship to contaminants should be undertaken in a larger subset of these populations.
Steven A. Ramm - One of the best experts on this subject based on the ideXlab platform.
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Baculum morphology predicts reproductive success of male house mice under sexual selection
BMC biology, 2013Co-Authors: Paula Stockley, Steven A. Ramm, Amy L. Sherborne, Michael D. Thom, Steve Paterson, Jane L. HurstAbstract:Background: Diversity in penile morphology is characterised by extraordinary variation in the size and shape of the Baculum (penis bone) found in many mammals. Although functionally enigmatic, diversity in Baculum form is hypothesised to result from sexual selection. According to this hypothesis, the Baculum should influence the outcome of reproductive competition among males within promiscuous mating systems. However, a test of this key prediction is currently lacking. Results: Here we show that Baculum size explains significant variation in the reproductive success of male house mice under competitive conditions. After controlling for body size and other reproductive traits, the width (but not length) of the house mouse Baculum predicts both the mean number of offspring sired per litter and total number of offspring sired. Conclusions: By providing the first evidence linking Baculum morphology to male reproductive success, our results support the hypothesis that evolutionary diversity in Baculum form is driven by sexual selection.
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genital morphology linked to social status in the bank vole myodes glareolus
Behavioral Ecology and Sociobiology, 2012Co-Authors: Nicola Jennings, Jean-françois Lemaître, Steven A. Ramm, Paula StockleyAbstract:Since genital morphology can influence the outcome of post-copulatory sexual selection, differences in the genitalia of dominant and subordinate males could be a factor contributing to the fertilisation advantage of dominant males under sperm competition. Here we investigate for the first time if penile morphology differs according to male social status in a promiscuous mammal, the bank vole (Myodes glareolus). In this species, dominant males typically achieve higher reproductive success than subordinates in post-copulatory sexual selection, and male genital morphology is complex, including both a Baculum (os penis) and penile spines. Our results show that despite no difference in body size associated with male social status, Baculum width is significantly larger in dominant male bank voles than in subordinates. We also found evidence of positive allometry and a relatively high coefficient of phenotypic variation in the Baculum width of male bank voles, consistent with an influence of sexual selection. By contrast, Baculum length and three measures of penile spinosity did not differ according to male social status or show evidence of positive allometry. We conclude that dominant male bank voles may benefit from an enlarged Baculum under sperm competition and/or cryptic female choice and that differences in penile morphology according to male social status might be important but as yet largely unexplored source of variation in male reproductive success.
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Sexual selection and the rodent Baculum: an intraspecific study in the house mouse (Mus musculus domesticus).
Genetica, 2009Co-Authors: Steven A. Ramm, Lin Khoo, Paula StockleyAbstract:The rapid divergence of genitalia is a pervasive trend in animal evolution, thought to be due to the action of sexual selection. To test predictions from the sexual selection hypothesis, we here report data on the allometry, variation, plasticity and condition dependence of Baculum morphology in the house mouse (Mus musculus domesticus). We find that that Baculum size: (a) exhibits no consistent pattern of allometric scaling (Baculum size being in most cases unrelated to body size), (b) exhibits low to moderate levels of phenotypic variation, (c) does not exhibit phenotypic plasticity in response to differences in perceived levels of sexual competition and (d) exhibits limited evidence of condition dependence. These patterns provide only limited evidence in support of the sexual selection hypothesis, and no consistent support for any particular sexual selection mechanism; however, more direct measures of how genital morphology influences male fertilization success are required.
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Sexual selection and genital evolution in mammals: a phylogenetic analysis of Baculum length.
The American naturalist, 2007Co-Authors: Steven A. RammAbstract:Abstract: Studies in invertebrate taxa suggest that postcopulatory sexual selection is an important factor in genital evolution. However, despite wide interspecific variation in genital morphology, evidence for an influence of sexual selection on mammalian genitalia is equivocal. Here I conduct phylogenetically controlled comparative analyses across four mammalian orders to assess how one aspect of this variation—male genital length—scales with (a) male body mass and (b) relative testis mass, the latter providing an index of the intensity of sperm competition. In all four orders, Baculum (=os penis) length is found to scale only weakly with male body mass. Both Baculum and glans penis length in rodents and Baculum length in carnivores are found to vary positively with relative testis mass. In contrast, there is no evidence to support an association between Baculum length and relative testis mass in either bats or primates. These results suggest that postcopulatory sexual selection influences genital lengt...
Abde Miftah Idrissi - One of the best experts on this subject based on the ideXlab platform.
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Effects of halogenated contaminants on reproductive development in wild mink (Neovison vison) from locations in Canada
Ecotoxicology, 2018Co-Authors: John E. Elliott, David Anthony Kirk, Pamela A. Martin, Laurie K. Wilson, Gabriela Kardosi, Tana Mcdaniel, Kimberley D. Hughes, Barry D. Smith, Abde Miftah IdrissiAbstract:The concept of the Anthropocene, that humans are now re-engineering global ecosystems, is in part evidenced by the pervasive pollution by persistent organic pollutants (POPs). Certain POPs are hormone mimics and can disrupt endocrine and hence reproductive processes, shown mainly by laboratory studies with model species. There are, in contrast, fewer confirmations of such disruption from eco-epidemiological studies of wild mammals. Here we used the American mink ( Neovison vison ) as a sentinel species for such a study. Over the period 1998–2006, 161 mink carcasses were obtained from commercial trappers in the Canadian provinces of British Columbia and Ontario. Mink were aged, sexed, measured, and body condition assessed. Livers were analyzed either individually or pooled for organochlorine (OC) pesticides, polychlorinated biphenyls (PCBs), and subsets for polybrominated diphenyl ethers (PBDEs). We primarily addressed whether contaminants affected male reproductive development by measuring Baculum size and assessing the influences of age and body condition. We also considered the influence of spatial variation on relative exposure and size of Baculum. Statistical models separated by age class revealed that significant relationships between Baculum length or mass and juvenile mink were mostly positive, whereas for adults and first year mink they were mostly negative. A significant negative relationship for adult mink was determined between DDE and both Baculum length and mass. For juvenile mink we found significant positive relationships between ∑PCBs, DDE and ∑PBDEs with Baculum length. Our results provide some indication of negative effects of halogenated contaminants on male reproductive development in wild mink, and the most likely candidate chemical is the confirmed anti-androgenic compound, DDE, rather than PCBs or other compounds.
Paula Stockley - One of the best experts on this subject based on the ideXlab platform.
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Baculum morphology predicts reproductive success of male house mice under sexual selection
BMC biology, 2013Co-Authors: Paula Stockley, Steven A. Ramm, Amy L. Sherborne, Michael D. Thom, Steve Paterson, Jane L. HurstAbstract:Background: Diversity in penile morphology is characterised by extraordinary variation in the size and shape of the Baculum (penis bone) found in many mammals. Although functionally enigmatic, diversity in Baculum form is hypothesised to result from sexual selection. According to this hypothesis, the Baculum should influence the outcome of reproductive competition among males within promiscuous mating systems. However, a test of this key prediction is currently lacking. Results: Here we show that Baculum size explains significant variation in the reproductive success of male house mice under competitive conditions. After controlling for body size and other reproductive traits, the width (but not length) of the house mouse Baculum predicts both the mean number of offspring sired per litter and total number of offspring sired. Conclusions: By providing the first evidence linking Baculum morphology to male reproductive success, our results support the hypothesis that evolutionary diversity in Baculum form is driven by sexual selection.
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genital morphology linked to social status in the bank vole myodes glareolus
Behavioral Ecology and Sociobiology, 2012Co-Authors: Nicola Jennings, Jean-françois Lemaître, Steven A. Ramm, Paula StockleyAbstract:Since genital morphology can influence the outcome of post-copulatory sexual selection, differences in the genitalia of dominant and subordinate males could be a factor contributing to the fertilisation advantage of dominant males under sperm competition. Here we investigate for the first time if penile morphology differs according to male social status in a promiscuous mammal, the bank vole (Myodes glareolus). In this species, dominant males typically achieve higher reproductive success than subordinates in post-copulatory sexual selection, and male genital morphology is complex, including both a Baculum (os penis) and penile spines. Our results show that despite no difference in body size associated with male social status, Baculum width is significantly larger in dominant male bank voles than in subordinates. We also found evidence of positive allometry and a relatively high coefficient of phenotypic variation in the Baculum width of male bank voles, consistent with an influence of sexual selection. By contrast, Baculum length and three measures of penile spinosity did not differ according to male social status or show evidence of positive allometry. We conclude that dominant male bank voles may benefit from an enlarged Baculum under sperm competition and/or cryptic female choice and that differences in penile morphology according to male social status might be important but as yet largely unexplored source of variation in male reproductive success.
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Sexual selection and the rodent Baculum: an intraspecific study in the house mouse (Mus musculus domesticus).
Genetica, 2009Co-Authors: Steven A. Ramm, Lin Khoo, Paula StockleyAbstract:The rapid divergence of genitalia is a pervasive trend in animal evolution, thought to be due to the action of sexual selection. To test predictions from the sexual selection hypothesis, we here report data on the allometry, variation, plasticity and condition dependence of Baculum morphology in the house mouse (Mus musculus domesticus). We find that that Baculum size: (a) exhibits no consistent pattern of allometric scaling (Baculum size being in most cases unrelated to body size), (b) exhibits low to moderate levels of phenotypic variation, (c) does not exhibit phenotypic plasticity in response to differences in perceived levels of sexual competition and (d) exhibits limited evidence of condition dependence. These patterns provide only limited evidence in support of the sexual selection hypothesis, and no consistent support for any particular sexual selection mechanism; however, more direct measures of how genital morphology influences male fertilization success are required.
Leigh W. Simmons - One of the best experts on this subject based on the ideXlab platform.
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Baculum shape and paternity success in house mice: evidence for genital coevolution.
Philosophical transactions of the Royal Society of London. Series B Biological sciences, 2020Co-Authors: Gonçalo I. André, Renée C. Firman, Leigh W. SimmonsAbstract:Sexual selection is believed to be responsible for the rapid divergence of male genitalia, which is a widely observed phenomenon across different taxa. Among mammals, the stimulatory role of male genitalia and female 'sensory perception' has been suggested to explain these evolutionary patterns. Recent research on house mice has shown that Baculum (penis bone) shape can respond to experimentally imposed sexual selection. Here, we explore the adaptive value of Baculum shape by performing two experiments that examine the effects of male and female genitalia on male reproductive success. Thus, we selected house mice (Mus musculus domesticus) from families characterized by extremes in Baculum shape (relative width) and examined paternity success in both non-competitive (monogamous) and competitive (polyandrous) contexts. Our analyses revealed that the relative Baculum shape of competing males influenced competitive paternity success, but that this effect was dependent on the breeding value for Baculum shape of the family from which females were derived. Our data provide novel insight into the potential mechanisms underlying the evolution of the house mouse Baculum and lend support to the stimulatory hypothesis for the coevolution of male and female genitalia. This article is part of the theme issue 'Fifty years of sperm competition'.
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The coevolution of male and female genitalia in a mammal: A quantitative genetic insight
Evolution; international journal of organic evolution, 2020Co-Authors: Gonçalo I. André, Renée C. Firman, Leigh W. SimmonsAbstract:Male genitalia are among the most phenotypically diverse morphological traits, and sexual selection is widely accepted as being responsible for their evolutionary divergence. Studies of house mice suggest that the shape of the Baculum (penis bone) affects male reproductive fitness and experimentally imposed postmating sexual selection has been shown to drive divergence in Baculum shape across generations. Much less is known of the morphology of female genitalia and its coevolution with male genitalia. In light of this, we used a paternal half-sibling design to explore patterns of additive genetic variation and covariation underlying Baculum shape and female vaginal tract size in house mice (Mus musculus domesticus). We applied a landmark-based morphometrics approach to measure Baculum size and shape in males and the length of the vaginal tract and width of the cervix in females. Our results reveal significant additive genetic variation in house mouse Baculum morphology and cervix width, as well as evidence for genetic covariation between male and female genital measures. Our data thereby provide novel insight into the potential for the coevolutionary divergence of male and female genital traits in a mammal.
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Phenotypic plasticity in genitalia: Baculum shape responds to sperm competition risk in house mice.
Proceedings. Biological sciences, 2018Co-Authors: Gonçalo I. André, Renée C. Firman, Leigh W. SimmonsAbstract:Males are known to adjust their expenditure on testes growth and sperm production in response to sperm competition risk. Genital morphology can also contribute to competitive fertilization success but whether male genital morphology can respond plastically to the sperm competition environment has received little attention. Here, we exposed male house mice to two different sperm competition environments during their sexual development and quantified phenotypic plasticity in Baculum morphology. The sperm competition environment generated plasticity in body growth. Males maturing under sperm competition risk were larger and heavier than males maturing under no sperm competition risk. We used a landmark-based geometric morphometric approach to measure Baculum size and shape. Independent of variation in body size, males maintained under risk of sperm competition had a relatively thicker and more distally extended Baculum bulb compared with males maintained under no sperm competition risk. Plasticity in Baculum shape paralleled evolutionary responses to selection from sperm competition reported in previous studies of house mice. Our findings provide experimental evidence of socially mediated phenotypic plasticity in male genitalia.
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Experimental evidence for the evolution of the Mammalian Baculum by sexual selection.
Evolution; international journal of organic evolution, 2013Co-Authors: Leigh W. Simmons, Renée C. FirmanAbstract:Male genitalia exhibit a taxonomically widespread pattern of rapid and divergent evolution. Sexual selection is generally believed to be responsible for these patterns of evolutionary divergence, although empirical support for the sexual selection hypothesis comes mainly from studies of insects. Here we show that sexual selection is responsible for an evolutionary divergence in Baculum morphology among populations of house mice Mus domesticus. We sourced mice from three isolated populations known to be subject to differing strengths of postcopulatory sexual selection and bred them under common-garden conditions. Mice from populations with strong postcopulatory sexual selection had bacula that were relatively thicker compared with mice from populations with weak selection. We used experimental evolution to determine whether these patterns of divergence could be ascribed to postcopulatory sexual selection. After 27 generations of experimental evolution, populations of mice subjected to postcopulatory sexual selection evolved bacula that were relatively thicker than populations subjected to enforced monogamy. Our data thereby provide evidence that postcopulatory sexual selection underlies an evolutionary divergence in the mammalian Baculum and supports the hypothesis that sexual selection plays a general role in the evolution of male genital morphology across evolutionary diverse taxonomic groups.
