Littorina fabalis is an intertidal snail commonly living on the brown algae Fucus vesiculosus and showing frequent shell-color polymorphisms in the wild. The evolutionary mechanism underlying this polymorphism is curr...Littorina fabalis is an intertidal snail commonly living on the brown algae Fucus vesiculosus and showing frequent shell-color polymorphisms in the wild. The evolutionary mechanism underlying this polymorphism is currently unknown. Shell color variation was studied in mated and non-mated specimens of this species from different microareas in one locality from NW Spain, in order to estimate sexual selection and assortative mating that may （still） be operating in this population. The analyses across microareas allowed us to investigate frequency-dependent selection and assortative mating components, mechanisms that could maintain the polymorphism. The presence of shell scars caused by crab attacks, an environmental variable not related with sexual selection or assortative mating, was used as experimental control. This study provides new evidence of significant disas- sortative mating and some degree of sexual selection against some shell colors, supporting the results found 21 years ago in a similar study, i.e. in the same species and locality. The similarity of these estimates during the studied period suggests that this experimental approach is consistent and valid to be extended to other populations and organisms. In addition, sexual selection and assortative mating estimates did not change across microareas differing in shell color frequencies, suggesting than the polymor- phism can not be maintained by a frequency-dependent （sexual selection-based） mechanism. Our main hypothesis is that negative assortative mating could contribute to the maintenance of the polymorphism, perhaps by males showing distinct female color preferences when searching for mates [Current Zoology 58 （3）： 463-474, 2012].展开更多
The term ＇assortative mating＇ has been applied to describe two very different phenomena： （1） the tendency for indi- viduals to choose phenotypically similar mates from among conspecifics; or （2） the tendency to...The term ＇assortative mating＇ has been applied to describe two very different phenomena： （1） the tendency for indi- viduals to choose phenotypically similar mates from among conspecifics; or （2） the tendency to prefer conspecific over hete- rospecific mates （behavioral reproductive isolation）. Both forms of assortative mating are widespread in nature, but the relation- ship between these behaviors remains unclear. Namely, it is plausible that a preference for phenotypically similar conspecifics in cidentally reduces the probability of mating with phenotypically divergent heterospecifics. We present a model to calculate how the level of reproductive isolation depends on intraspecific assortative mating and the phenotypic divergence between species. For empirically reasonable levels of intraspecific assortment on a single trait axis, we show that strong reproductive isolation requires very substantial phenotypic divergence. We illustrate this point by applying our model to empirical data from threespine stickleback Gasterosteus aculeatus and Darwin＇s Finches （Geospiza spp）. We conclude that typical levels of intraspecific assortment cannot generally be extrapolated to explain levels of interspecific reproductive isolation. Instead, reproductive isolation between species likely arises from different mate choice behaviors, or multivariate assortative mating [Current Zoology 58 （3）： 484-492, 2012].展开更多
Sexual dimorphism is often used as a proxy for the intensity of sexual selection in comparative studies of sexual selection and diversification. The Mexican Goodeinae are a group of livebearing freshwater fishes with ...Sexual dimorphism is often used as a proxy for the intensity of sexual selection in comparative studies of sexual selection and diversification. The Mexican Goodeinae are a group of livebearing freshwater fishes with large variation between species in sexual dimorphism in body shape. Previously we found an association between variation in morphological sexual dimorphism between species and the amount of gene flow within populations in the Goodeinae. Here we have examined if mor- phological differentiation within a single dimorphic species is related to assortative mating or gene flow between populations. In the Amarillo fish Girardinichthys multiradiatus studies have shown that exaggerated male fins are targets of female preferences. We find that populations of the species differ in the level of sexual dimorphism displayed due to faster evolution of differences in male than female morphology. However, this does not predict variation in assortative mating tests in the laboratory; in fact dif- ferences in male morphology are negatively correlated with assortative mating. Microsatellite markers reveal significant genetic differences between populations. However, gene flow is not predicted by either morphological differences or assortative mating. Rather, it demonstrates a pattern of isolation by distance with greater differentiation between watersheds. We discuss the caveats of predicting behavioural and genetic divergence from so-called proxies of sexual selection [Current Zoology 58 （3）： 440-452, 2012].展开更多
Anthropogenic pollutants have the potential to disrupt reproductive strategies. Little is known about how lead （Pb2＋） exposure disrupts individual-level responses in reproductive behaviors, which are important for ...Anthropogenic pollutants have the potential to disrupt reproductive strategies. Little is known about how lead （Pb2＋） exposure disrupts individual-level responses in reproductive behaviors, which are important for fitness. Drosophila melanogaster was used as a model system to deter- mine the effects of： 1） developmental lead exposure on pre-mating reproductive behaviors （i.e., mate preference）, and 2） lead exposure and mating preferences on fitness in the F0 parental generation and F1 un-exposed offspring. Wild-type strains of D. melanogaster were reared from egg stage to adulthood in control or leaded medium （250 μM PbAc） and tested for differences in： mate preference, male song performance, sex pheromone expression, fecundity, mortality, and body weight. F0 leaded females preferentially mated with leaded males （i.e., asymmetrical positive assortative mating） in 2-choice tests. This positive assortative mating was mediated by the females （and not the males） and was dependent upon context and developmental exposure to Pb. Neither the courtship song nor the sex pheromone profile expressed by control and leaded males medi- ated the positive assortative mating in leaded females. Leaded females did not incur a fitness cost in terms of reduced fecundity, increased mortality, or decreased body weight by mating with leaded males. These results suggest that sublethal exposure to lead during development can alter mate preferences in adults, but not fitness measures once lead exposure has been removed. We suggest that changes in mate preference may induce fitness costs, as well as long-term population and multi-generational implications, if pollution is persistent in the environment.展开更多
Sex differences in plumage color are common in bird species.Some bird species are regarded as sexually monochromatic in human visual systems,and in recent years,some species are found to be of cryptic(to human)sexual ...Sex differences in plumage color are common in bird species.Some bird species are regarded as sexually monochromatic in human visual systems,and in recent years,some species are found to be of cryptic(to human)sexual dichromatism by spectrophotometric techniques.However,the functions of plumage color are still less understood in these species.Here,we focused on plumage color traits in the Chestnut Thrush(Turdus rubrocanus),which is considered as a sexually monochromatic bird by human observers.We used spectrometer analyses and avian visual modeling to investigate the color traits of males and females,and whether these color traits are involved in assortative mating.We found that Chestnut Thrush showed sexual dichromatism in bill,throat and wing,and pairs mated assortatively with colorations of throat,chest,crown and wing.We also found that color of tarsus was different between two consecutive years.These results revealed that Chestnut Thrush is sexually dichromatic in the avian visual system,and plumage color traits play important roles in mate choice.展开更多
Mating patterns in angiosperms are typically nonrandom,yet the mechanisms driving nonrandom mating remain unclear,especially regarding the effects of quantitative floral traits on plant mating success across male and ...Mating patterns in angiosperms are typically nonrandom,yet the mechanisms driving nonrandom mating remain unclear,especially regarding the effects of quantitative floral traits on plant mating success across male and female functions.In this study,we investigated how variation in spur length and flower number per plant influences mating patterns in Aquilegia rockii within a natural population.Using marker-based paternity analyses and manipulative experiments,we assessed the role of these traits in mating success across both sexual functions.We found significant variation in the mate composition between male and female function,with spur-length frequency positively associated with female outcrossing rate and mate number,but not with male outcrossing or mate number.Most mating events occurred within 10 m,and spur-length frequency positively correlated with mating distance.Regardless of selfing,there was evidence for assortative mating for spur length.Although spur length did not correlate with pollinator visitation,plants with mid-length spurs had higher seed set than those with shorter or longer spurs when autonomous selfing was excluded.Flowers number per plant was only associated with mating distance and female outcrossing rate.Our results suggest that spur length plays a key role in nonrandom mating by frequency-dependent mating,with implications for stabilizing selection and maintenance of genetic diversity.This study advances our understanding of floral diversity by dissecting the role of quantitative floral traits in plant mating through both female and male functions.展开更多
The extent to which sexual selection is involved in speciation with gene flow remains an open question and the sub- ject of much research. Here, we propose that some insight can be gained from considering the concept ...The extent to which sexual selection is involved in speciation with gene flow remains an open question and the sub- ject of much research. Here, we propose that some insight can be gained from considering the concept of magic traits （i.e., traits involved in both reproductive isolation and ecological divergence）. Both magic traits and other, ＂non-magic＂, traits can contribute to speciation via a number of specific mechanisms. We argue that many of these mechanisms are likely to differ widely in the ex- tent to which they involve sexual selection. Furthermore, in some cases where sexual selection is present, it may be prone to in- hibit rather than drive speciation. Finally, there are a priori reasons to believe that certain categories of traits are much more ef- fective than others in driving speciation. The combination of these points suggests a classification of traits that may shed light on the broader role of sexual selection in speciation with gene flow. In particular, we suggest that sexual selection can act as a driver of speciation in some scenarios, but may play a negligible role in potentially common categories of magic traits, and may be likely to inhibit speciation in common categories of non-magic traits [Current Zoology 58 （3）： 510-516, 2012].展开更多
Genetic, life history, and environmental factors dictate patterns of variation in sexual traits within and across popula- tions, and thus the action and outcome of sexual selection. This study explores patterns of inh...Genetic, life history, and environmental factors dictate patterns of variation in sexual traits within and across popula- tions, and thus the action and outcome of sexual selection. This study explores patterns of inheritance, diet, age, and mate-choice copying on the expression of male sexual signals and associated female mate choice in a phenotypically diverse group of Schizo- cosa wolf spiders. Focal spiders exhibit one of two male phenotypes： ＇omamented＇ males possess large black brushes on their fo- relegs, and ＇non-ornamented＇ males possess no brushes. Using a quantitative genetics breeding design in a mixed population of ornamented/non-ornamented males, we found a strong genetic basis to male phenotype and female choice. We also found that some ornamented males produced some sons with large brushes and others with barely visible brushes. Results of diet manipula- tions and behavioral mating trials showed no influence of diet on male phenotype or female mate choice. Age post maturation, however, influenced mate choice, with younger females being more likely to mate with ornamented males. A mate-choice copy- ing experiment found that, following observations of another female＇s mate choice/copulation, virgin mature females tended to match the mate choice （ornamented vs. non-ornamented males） of the females they observed. Finally, analyses of genetic varia- tion across phenotypically pure （only one male phenotype present） vs. mixed （both phenotypes present） populations revealed ge- netic distinction between phenotypes in phenotypically-pure populations, but no distinctionin phenotypically-mixed populations. The difference in patterns of genetic differentiation and mating across geographic locations suggests a complex network of fac- tors contributing to the outcome of sexual selection .展开更多
Mating preferences can show extreme variation within and among individuals even when sensory inputs are conserved. This variation is a result of changes associated with evaluative mechanisms that assign positive, neut...Mating preferences can show extreme variation within and among individuals even when sensory inputs are conserved. This variation is a result of changes associated with evaluative mechanisms that assign positive, neutral, or negative hedonic value to stimuli--that is, label them as attractive, uninteresting, or unattractive. There is widespread behavioral evidence for differences in genes, environmental cues, or social experience leading to marked changes in the hedonic value of stimuli. Evaluation is accomplished through an array of mechanisms that are readily modifiable through genetic changes or environmental inputs, and that may often result in the rapid acquisition or loss of behavioral preferences. Reversals in preference arising from ＂flips＂ in hedonic value may be quite common. Incorporating such discontinuous changes into models of preference evolution may illuminate our understanding of processes like trait diversification, sexual conflict, and sympatric speciation.展开更多
Low desiccation resistance of Drosophila ananassae reflects its rarity outside the humid tropics. However, the ability of this sensitive species to evolve under seasonally varying subtropical areas is largely unknown....Low desiccation resistance of Drosophila ananassae reflects its rarity outside the humid tropics. However, the ability of this sensitive species to evolve under seasonally varying subtropical areas is largely unknown. D. ananassae flies are mostly lighter during the rainy season but darker and lighter flies occur in the autumn season in northern India. We tested the hypothesis whether seasonally varying alternative body color phenotypes of D. ananassae vary in their levels of environmental stress tolerances and mating behavior. Thus, we investigated D. ananassae flies collected during rainy and autumn seasons for changes in body melanization and their genetic basis, desiccation-related traits, cold tolerance and mating propensity. On the basis of genetic crosses, we found total body color dimorphism consistent with a single gene model in both sexes olD. ananassae. A significant increase in the frequency of the dark morph was observed during the drier autumn season, and body color phenotypes showed significant deviations from Hardy-Weinberg equilibrium, which suggests climatic selection plays a role. Resistance to desiccation as well as cold stress were two- to three-fold higher in the dark body color strain as compared with the light strain. On the basis of no-choice mating experiments, we observed significantly higher assortative matings between dark morphs under desiccation or cold stress, and between light morphs under hot or higher humidity conditions. To the best of our knowledge, this is the first report on the ecological significance of seasonally varying total body color dimorphism in a tropical species, D. ananassae.展开更多
文摘Littorina fabalis is an intertidal snail commonly living on the brown algae Fucus vesiculosus and showing frequent shell-color polymorphisms in the wild. The evolutionary mechanism underlying this polymorphism is currently unknown. Shell color variation was studied in mated and non-mated specimens of this species from different microareas in one locality from NW Spain, in order to estimate sexual selection and assortative mating that may （still） be operating in this population. The analyses across microareas allowed us to investigate frequency-dependent selection and assortative mating components, mechanisms that could maintain the polymorphism. The presence of shell scars caused by crab attacks, an environmental variable not related with sexual selection or assortative mating, was used as experimental control. This study provides new evidence of significant disas- sortative mating and some degree of sexual selection against some shell colors, supporting the results found 21 years ago in a similar study, i.e. in the same species and locality. The similarity of these estimates during the studied period suggests that this experimental approach is consistent and valid to be extended to other populations and organisms. In addition, sexual selection and assortative mating estimates did not change across microareas differing in shell color frequencies, suggesting than the polymor- phism can not be maintained by a frequency-dependent （sexual selection-based） mechanism. Our main hypothesis is that negative assortative mating could contribute to the maintenance of the polymorphism, perhaps by males showing distinct female color preferences when searching for mates [Current Zoology 58 （3）： 463-474, 2012].
文摘The term ＇assortative mating＇ has been applied to describe two very different phenomena： （1） the tendency for indi- viduals to choose phenotypically similar mates from among conspecifics; or （2） the tendency to prefer conspecific over hete- rospecific mates （behavioral reproductive isolation）. Both forms of assortative mating are widespread in nature, but the relation- ship between these behaviors remains unclear. Namely, it is plausible that a preference for phenotypically similar conspecifics in cidentally reduces the probability of mating with phenotypically divergent heterospecifics. We present a model to calculate how the level of reproductive isolation depends on intraspecific assortative mating and the phenotypic divergence between species. For empirically reasonable levels of intraspecific assortment on a single trait axis, we show that strong reproductive isolation requires very substantial phenotypic divergence. We illustrate this point by applying our model to empirical data from threespine stickleback Gasterosteus aculeatus and Darwin＇s Finches （Geospiza spp）. We conclude that typical levels of intraspecific assortment cannot generally be extrapolated to explain levels of interspecific reproductive isolation. Instead, reproductive isolation between species likely arises from different mate choice behaviors, or multivariate assortative mating [Current Zoology 58 （3）： 484-492, 2012].
文摘Sexual dimorphism is often used as a proxy for the intensity of sexual selection in comparative studies of sexual selection and diversification. The Mexican Goodeinae are a group of livebearing freshwater fishes with large variation between species in sexual dimorphism in body shape. Previously we found an association between variation in morphological sexual dimorphism between species and the amount of gene flow within populations in the Goodeinae. Here we have examined if mor- phological differentiation within a single dimorphic species is related to assortative mating or gene flow between populations. In the Amarillo fish Girardinichthys multiradiatus studies have shown that exaggerated male fins are targets of female preferences. We find that populations of the species differ in the level of sexual dimorphism displayed due to faster evolution of differences in male than female morphology. However, this does not predict variation in assortative mating tests in the laboratory; in fact dif- ferences in male morphology are negatively correlated with assortative mating. Microsatellite markers reveal significant genetic differences between populations. However, gene flow is not predicted by either morphological differences or assortative mating. Rather, it demonstrates a pattern of isolation by distance with greater differentiation between watersheds. We discuss the caveats of predicting behavioural and genetic divergence from so-called proxies of sexual selection [Current Zoology 58 （3）： 440-452, 2012].
文摘Anthropogenic pollutants have the potential to disrupt reproductive strategies. Little is known about how lead （Pb2＋） exposure disrupts individual-level responses in reproductive behaviors, which are important for fitness. Drosophila melanogaster was used as a model system to deter- mine the effects of： 1） developmental lead exposure on pre-mating reproductive behaviors （i.e., mate preference）, and 2） lead exposure and mating preferences on fitness in the F0 parental generation and F1 un-exposed offspring. Wild-type strains of D. melanogaster were reared from egg stage to adulthood in control or leaded medium （250 μM PbAc） and tested for differences in： mate preference, male song performance, sex pheromone expression, fecundity, mortality, and body weight. F0 leaded females preferentially mated with leaded males （i.e., asymmetrical positive assortative mating） in 2-choice tests. This positive assortative mating was mediated by the females （and not the males） and was dependent upon context and developmental exposure to Pb. Neither the courtship song nor the sex pheromone profile expressed by control and leaded males medi- ated the positive assortative mating in leaded females. Leaded females did not incur a fitness cost in terms of reduced fecundity, increased mortality, or decreased body weight by mating with leaded males. These results suggest that sublethal exposure to lead during development can alter mate preferences in adults, but not fitness measures once lead exposure has been removed. We suggest that changes in mate preference may induce fitness costs, as well as long-term population and multi-generational implications, if pollution is persistent in the environment.
基金supported by the National Natural Science Foundation of China(No.32070452to YS)。
文摘Sex differences in plumage color are common in bird species.Some bird species are regarded as sexually monochromatic in human visual systems,and in recent years,some species are found to be of cryptic(to human)sexual dichromatism by spectrophotometric techniques.However,the functions of plumage color are still less understood in these species.Here,we focused on plumage color traits in the Chestnut Thrush(Turdus rubrocanus),which is considered as a sexually monochromatic bird by human observers.We used spectrometer analyses and avian visual modeling to investigate the color traits of males and females,and whether these color traits are involved in assortative mating.We found that Chestnut Thrush showed sexual dichromatism in bill,throat and wing,and pairs mated assortatively with colorations of throat,chest,crown and wing.We also found that color of tarsus was different between two consecutive years.These results revealed that Chestnut Thrush is sexually dichromatic in the avian visual system,and plumage color traits play important roles in mate choice.
基金financially supported by the National Natural Science Foundation of China(32271693)the Cultivating Plan Program for the Leader in Science and Technology of Yunnan Province(202405AC350111)to ZQZ.
文摘Mating patterns in angiosperms are typically nonrandom,yet the mechanisms driving nonrandom mating remain unclear,especially regarding the effects of quantitative floral traits on plant mating success across male and female functions.In this study,we investigated how variation in spur length and flower number per plant influences mating patterns in Aquilegia rockii within a natural population.Using marker-based paternity analyses and manipulative experiments,we assessed the role of these traits in mating success across both sexual functions.We found significant variation in the mate composition between male and female function,with spur-length frequency positively associated with female outcrossing rate and mate number,but not with male outcrossing or mate number.Most mating events occurred within 10 m,and spur-length frequency positively correlated with mating distance.Regardless of selfing,there was evidence for assortative mating for spur length.Although spur length did not correlate with pollinator visitation,plants with mid-length spurs had higher seed set than those with shorter or longer spurs when autonomous selfing was excluded.Flowers number per plant was only associated with mating distance and female outcrossing rate.Our results suggest that spur length plays a key role in nonrandom mating by frequency-dependent mating,with implications for stabilizing selection and maintenance of genetic diversity.This study advances our understanding of floral diversity by dissecting the role of quantitative floral traits in plant mating through both female and male functions.
文摘The extent to which sexual selection is involved in speciation with gene flow remains an open question and the sub- ject of much research. Here, we propose that some insight can be gained from considering the concept of magic traits （i.e., traits involved in both reproductive isolation and ecological divergence）. Both magic traits and other, ＂non-magic＂, traits can contribute to speciation via a number of specific mechanisms. We argue that many of these mechanisms are likely to differ widely in the ex- tent to which they involve sexual selection. Furthermore, in some cases where sexual selection is present, it may be prone to in- hibit rather than drive speciation. Finally, there are a priori reasons to believe that certain categories of traits are much more ef- fective than others in driving speciation. The combination of these points suggests a classification of traits that may shed light on the broader role of sexual selection in speciation with gene flow. In particular, we suggest that sexual selection can act as a driver of speciation in some scenarios, but may play a negligible role in potentially common categories of magic traits, and may be likely to inhibit speciation in common categories of non-magic traits [Current Zoology 58 （3）： 510-516, 2012].
文摘Genetic, life history, and environmental factors dictate patterns of variation in sexual traits within and across popula- tions, and thus the action and outcome of sexual selection. This study explores patterns of inheritance, diet, age, and mate-choice copying on the expression of male sexual signals and associated female mate choice in a phenotypically diverse group of Schizo- cosa wolf spiders. Focal spiders exhibit one of two male phenotypes： ＇omamented＇ males possess large black brushes on their fo- relegs, and ＇non-ornamented＇ males possess no brushes. Using a quantitative genetics breeding design in a mixed population of ornamented/non-ornamented males, we found a strong genetic basis to male phenotype and female choice. We also found that some ornamented males produced some sons with large brushes and others with barely visible brushes. Results of diet manipula- tions and behavioral mating trials showed no influence of diet on male phenotype or female mate choice. Age post maturation, however, influenced mate choice, with younger females being more likely to mate with ornamented males. A mate-choice copy- ing experiment found that, following observations of another female＇s mate choice/copulation, virgin mature females tended to match the mate choice （ornamented vs. non-ornamented males） of the females they observed. Finally, analyses of genetic varia- tion across phenotypically pure （only one male phenotype present） vs. mixed （both phenotypes present） populations revealed ge- netic distinction between phenotypes in phenotypically-pure populations, but no distinctionin phenotypically-mixed populations. The difference in patterns of genetic differentiation and mating across geographic locations suggests a complex network of fac- tors contributing to the outcome of sexual selection .
文摘Mating preferences can show extreme variation within and among individuals even when sensory inputs are conserved. This variation is a result of changes associated with evaluative mechanisms that assign positive, neutral, or negative hedonic value to stimuli--that is, label them as attractive, uninteresting, or unattractive. There is widespread behavioral evidence for differences in genes, environmental cues, or social experience leading to marked changes in the hedonic value of stimuli. Evaluation is accomplished through an array of mechanisms that are readily modifiable through genetic changes or environmental inputs, and that may often result in the rapid acquisition or loss of behavioral preferences. Reversals in preference arising from ＂flips＂ in hedonic value may be quite common. Incorporating such discontinuous changes into models of preference evolution may illuminate our understanding of processes like trait diversification, sexual conflict, and sympatric speciation.
文摘Low desiccation resistance of Drosophila ananassae reflects its rarity outside the humid tropics. However, the ability of this sensitive species to evolve under seasonally varying subtropical areas is largely unknown. D. ananassae flies are mostly lighter during the rainy season but darker and lighter flies occur in the autumn season in northern India. We tested the hypothesis whether seasonally varying alternative body color phenotypes of D. ananassae vary in their levels of environmental stress tolerances and mating behavior. Thus, we investigated D. ananassae flies collected during rainy and autumn seasons for changes in body melanization and their genetic basis, desiccation-related traits, cold tolerance and mating propensity. On the basis of genetic crosses, we found total body color dimorphism consistent with a single gene model in both sexes olD. ananassae. A significant increase in the frequency of the dark morph was observed during the drier autumn season, and body color phenotypes showed significant deviations from Hardy-Weinberg equilibrium, which suggests climatic selection plays a role. Resistance to desiccation as well as cold stress were two- to three-fold higher in the dark body color strain as compared with the light strain. On the basis of no-choice mating experiments, we observed significantly higher assortative matings between dark morphs under desiccation or cold stress, and between light morphs under hot or higher humidity conditions. To the best of our knowledge, this is the first report on the ecological significance of seasonally varying total body color dimorphism in a tropical species, D. ananassae.
