Research on the role of sexual selection in the speciation process largely focuses on the diversifying role of mate choice. In particular, much attention has been drawn to the fact that population divergence in mate c...Research on the role of sexual selection in the speciation process largely focuses on the diversifying role of mate choice. In particular, much attention has been drawn to the fact that population divergence in mate choice and in the male traits subject to choice directly can lead to assortative mating. However, male contest competition over mates also constitutes an important mechanism of sexual selection. We review recent empirical studies and argue that sexual selection through male contest competition can affect speciation in ways other than mate choice. For example, biases in aggression towards similar competitors can lead to disruptive and negative frequency-dependent selection on the traits used in contest competition in a similar way as competition for other types of limited resources. Moreover, male contest abilities often trade-off against other abilities such as parasite resistance, protection against predators and general stress tolerance. Populations experiencing different ecological condi- tions should therefore quickly diverge non-randomly in a number of traits including male contest abilities. In resource based breeding systems, a feedback loop between competitive ability and habitat use may lead to further population divergence. We discuss how population divergence in traits used in male contest competition can lead to the build up of reproductive isolation through a number of different pathways. Our main conclusion is that the role of male contest competition in speciation remains largely scientifically unexplored [Current Zoology 58 （3）： 493-509, 2012].展开更多
Environmental noise has a significant negative impact on acoustic communication in most situations,as it influences the production,transmis-sion,and reception of acoustic signals.However,how animals respond to conspec...Environmental noise has a significant negative impact on acoustic communication in most situations,as it influences the production,transmis-sion,and reception of acoustic signals.However,how animals respond to conspecific sounds when there is interference from environmental noise,and whether males and females display convergent behavioral responses in the face of noise masking remain poorly understood.In this study,we investigated the effects of conspecific male advertisement calls with different signal-to-noise ratios on male-male competition and female choice in the Anhui tree frog Rhacophorus zhoukaiyae using playback and phonotaxis experiments,respectively.The results showed that(1)female Anhui tree frogs preferentially selected the conspecific calls with higher SNR compared to calls with lower SNR;(2)males preferen-tially responded vocally to the conspecific calls with higher SNR compared to calls with lower SNR;and(3)males'competitive strategies were flexible in the face of noise interference.These results suggest that preferences of both sexes converge in outcome,and that male competitive strategies may depend on predictable female preferences.This study will provide an important basis for further research on decision-making in animals.展开更多
Research on sexual selection and hybridization has focused on female mate choice and male-male competition. While the evolutionary outcomes of interspecific female preference have been well explored, we are now gainin...Research on sexual selection and hybridization has focused on female mate choice and male-male competition. While the evolutionary outcomes of interspecific female preference have been well explored, we are now gaining a better understanding of the processes by which male-male compe- tition between species in secondary contact promotes reproductive isolation versus hybridization. What is relatively unexplored is the interaction between female choice and male competition, as they can oppose one another or align with similar outcomes for reproductive isolation. The role of female-female competition in hybridization is also not well understood, but could operate similarly to male-male competition in polyandrous and other systems where costs to heterospecific mating are low for females. Reproductive competition between either sex of sympatric species can cause the divergence and/or convergence of sexual signals and recognition, which in turn influences the likelihood for interspecific mating. Future work on species interactions in secondary contact should test the relative influences of both mate choice and competition for mates on hybridization outcomes, and should not ignore the possibilities that females can compete over mating resources, and males can exercise mate choice.展开更多
Male reproductive tactics vary widely across the species of the ant genus Cardiocondyla, from obligatory lethal combat among co-occurring males to complete mutual tolerance. The African species C. venustula Wheeler, 1...Male reproductive tactics vary widely across the species of the ant genus Cardiocondyla, from obligatory lethal combat among co-occurring males to complete mutual tolerance. The African species C. venustula Wheeler, 1908 has an intermediate phylogenetic position between taxa with fighting males and taxa with tolerant males and also shows an intermediate male behavior. Males from 2 native populations in South Africa and a population introduced to Puerto Rico attacked and killed freshly eclosing rivals but rarely engaged in deadly fights with adult competitors, Instead, several males per colony established small ＂territories＂ in their natal nests and defended them against other males. Males with a stable territory had more contact with female sexuals than nonterritorial males and more frequently engaged in mating attempts. In controlled choice experiments, female sexuals did not show any preference for particular males. We suggest that male territoriality in C. venustula is an adaptation to the seasonal production of large numbers of female sexuals by multiple mothers.展开更多
Natural selection has been shown to drive population differentiation and speciation. The role of sexual selection in this process is controversial; however, most of the work has centered on mate choice while the role ...Natural selection has been shown to drive population differentiation and speciation. The role of sexual selection in this process is controversial; however, most of the work has centered on mate choice while the role of male-male competition in speciation is relatively understudied. Here, we outline how male-male competition can be a source of diversifying selection on male competitive phenotypes, and how this can contribute to the evolution of reproductive isolation. We highlight how negative frequency-dependent selection （advantage of rare phenotype arising from stronger male-male competition between similar male phenotypes compared with dissimilar male pheno- types） and disruptive selection （advantage of extreme phenotypes） drives the evolution of diversity in competitive traits such as weapon size, nuptial coloration, or aggressiveness. We underscore that male-male competition interacts with other life-history functions and that variable male com- petitive phenotypes may represent alternative adaptive options. In addition to competition for mates, aggressive interference competition for ecological resources can exert selection on compet- itor signals. We call for a better integration of male-male competition with ecological interference competition since both can influence the process of speciation via comparable but distinct mecha- nisms. Altogether, we present a more comprehensive framework for studying the role of male-male competition in speciation, and emphasize the need for better integration of insights gained from other fields studying the evolutionary, behavioral, and physiological consequences of agonistic interactions.展开更多
Diversification in sexual signals is often taken as evidenee for the importance of sexual selection in speciatio n.However,in order for sexual selection to gen erate reproductive isolati on between populations,both si...Diversification in sexual signals is often taken as evidenee for the importance of sexual selection in speciatio n.However,in order for sexual selection to gen erate reproductive isolati on between populations,both signals and mate preferences must diverge together.Furthermore,assortative mating may result from multiple behavioral mecha nisms,in eluding female mate pref ere nces,male mate preferences,and male-male competition;yet their relative contributions are rarely evaluated.Here,we explored the role of mate pref ere nces and male competitive ability as pote ntial barriers to gene flow between 2 diverge nt lineages of the taw ny dragon lizard,Ctenophorus decresii,which differ in male throat coloration.We found stronger behavioral barriers to pairings between southern lineage males and northern lineage females than between northern males and southern females,indicating incomplete and asymmetric behavioral isolating barriers.These results were driven by both male and female mate preferences rather than lineage differences in male competitive ability.In trasexual selecti on is therefore un likely to drive the outcome of sec on dary contact in C.decresii,despite its widely ack no wledged importa nee in lizards.Our results are consiste nt with the emergi ng view that although both male and female mate pref ere nces can diverge alongside sexual signals,speciation is rarely driven by divergent sexual selection alone.展开更多
Sensory drive predicts that the conditions under which signaling takes place have large effects on signals, sensory systems, and behavior. The coupling of an ecological genetics approach with sen sory drive has been f...Sensory drive predicts that the conditions under which signaling takes place have large effects on signals, sensory systems, and behavior. The coupling of an ecological genetics approach with sen sory drive has been fruitful. An ecological genetics approach compares populations that experi ence different environments and asks whether population differences are adaptive and are the result of genetic and/or environmental variation. The multifaceted effects of signaling environ ments are wellexemplified by the bluefin killifish. In this system, males with blue anal fins are abundant in tanninstained swamps that lack UV/blue light but are absent in clear springs where UV/blue light is abundant. Past work indicates that lighting environments shape genetic and envir onmental variation in color patterns, visual systems, and behavior. Less is known about the select ive forces creating the across population correlations between UV/blue light and the abundance of blue males. Here, we present three new experiments that investigate the roles of lighting environ ments on male competition, female mate choice, and predation. We found strong effects of lighting environments on male competition where blue males were more likely to emerge as dominant in teastained water than in clear water. Our preliminary study on predation indicated that blue males may be less susceptible to predation in teastained water than in clear water. However, there was little evidence for female preferences favoring blue males. The resulting pattern is one where the effects of lighting environments on genetic variation and phenotypic plasticity match the direction of selection and favor the expression of blue males in swamps.展开更多
Our knowledge of how male competition contributes to speciation is dominated by investigations of competition between within-species morphs or closely related species that differ in conspicuous traits expressed during...Our knowledge of how male competition contributes to speciation is dominated by investigations of competition between within-species morphs or closely related species that differ in conspicuous traits expressed during the breeding season （e.g. color, song）. In such studies, it is important to consider the manner in which putatively sexually selected traits influence the outcome of competitive interactions within and between types because these traits can communicate information about competitor quality and may not be utilized by homotypic and heterotypic receivers in the same way. We studied the roles of breeding color and aggressive behaviors in competition within and between two divergent threes- pine stickleback Gasterosteus aculeatus color types. Our previous work in this system showed that the switch from red to black breeding coloration is associated with changes in male competition biases. Here, we find that red and black males also use different currencies in competition. Winners of both color types performed more aggressive behaviors than losers, regardless of whether the competitor was of the same or opposite color type. But breeding color differently predicted competitive outcomes for red and black males. Males who were redder at the start of competition were more likely to win when paired with homotypic competitors and less likely to win when paired with heterotypic competitors. In contrast, black color, though expressed in the breeding season and condition dependent, was unrelated to competitive outcomes. Placing questions about the role of male competition in speciation in a sexual signal evolution framework may provide insight into the ＂why and how＂ of aggression biases and asymmetries in competitive ability between closely related morphs and species.展开更多
Males evolved plastic strategies to respond to male-male competition and exhibit adaptive traits and behaviors maximizing their access to the females and limiting sperm competition.Mating behaviors allow males to expr...Males evolved plastic strategies to respond to male-male competition and exhibit adaptive traits and behaviors maximizing their access to the females and limiting sperm competition.Mating behaviors allow males to express quick responses to current sexual audience,that is,the number of nearby conspecifics prone to mate.In contrast,physiological responses are frequently delayed because they are constrained by the time and resources having to be mobilized to produce and export sperm and associated products.This is especially critical in species for which males produce spermatophores.Here we investigated in what extend moth males(the tortricid moth Lobesia botrana)producing spermatophores exhibit plastic behavioral and physiological responses to different sexual audiences before and during mating and the consequences for their reproductive output.We found that males adjusted their mating behaviors and spermatophore size to a potentially elevated risk of sperm competition perceived before mating.In addition,males responded to the closed presence of females during mating by reducing their mating duration.Surprisingly,the various behavioral and physiological responses we highlighted here were not fully reflected in their reproductive performance as we did not reveal any effect on fecundity and fertility of their mate.The selective pressure exerted on males experiencing male-male competition could thus be sufficient to trigger adjustment in male mating behaviors but constrains physiological responses according to the perception of competition.展开更多
Male-male competition and female mate choice may both play important roles in driving and maintaining reproductive isolation between species. When previously allopatric species come into secondary contact with each ot...Male-male competition and female mate choice may both play important roles in driving and maintaining reproductive isolation between species. When previously allopatric species come into secondary contact with each other due to introductions, they provide an opportunity to evaluate the identity and strength of reproductive isolating mechanisms. If reproductive isolation is not maintained, hybridization may occur. We examined how reproductive isolating mechanisms medi- ate hybridization between endemic populations of the Red River pupfish Cyprinodon rubrofluviati- lis and the recently introduced sheepshead minnow C. variegatus. In lab-based dominance trials, males of both species won the same number of competitions. However, male C. rubrofluviatilis that won competitions were more aggressive than C, variegatus winners, and more aggression was needed to win against competitor C. variagatus than allopatric C. rubrofluviatilis. Duration of fights also differed based on the relatedness of the competitor. In dichotomous mate choice trials, there were no conspecific or heterospecific preferences expressed by females of either species. Our findings that male-male aggression differs between closely and distantly related groups, but female choice does not suggest that male-male competition may be the more likely mechanism to impede gene flow in this system.展开更多
文摘Research on the role of sexual selection in the speciation process largely focuses on the diversifying role of mate choice. In particular, much attention has been drawn to the fact that population divergence in mate choice and in the male traits subject to choice directly can lead to assortative mating. However, male contest competition over mates also constitutes an important mechanism of sexual selection. We review recent empirical studies and argue that sexual selection through male contest competition can affect speciation in ways other than mate choice. For example, biases in aggression towards similar competitors can lead to disruptive and negative frequency-dependent selection on the traits used in contest competition in a similar way as competition for other types of limited resources. Moreover, male contest abilities often trade-off against other abilities such as parasite resistance, protection against predators and general stress tolerance. Populations experiencing different ecological condi- tions should therefore quickly diverge non-randomly in a number of traits including male contest abilities. In resource based breeding systems, a feedback loop between competitive ability and habitat use may lead to further population divergence. We discuss how population divergence in traits used in male contest competition can lead to the build up of reproductive isolation through a number of different pathways. Our main conclusion is that the role of male contest competition in speciation remains largely scientifically unexplored [Current Zoology 58 （3）： 493-509, 2012].
基金supported by the grants from the National Natural Science Foundation of China(Nos.32170504,31970422,and 31672305)to Guangzhan Fangthe grant from the Biodiversity Survey,Monitoring and Assessment Project of Ministry of Ecology and Environment of China(No.2019HB2096001006)to Baowei Zhang.
文摘Environmental noise has a significant negative impact on acoustic communication in most situations,as it influences the production,transmis-sion,and reception of acoustic signals.However,how animals respond to conspecific sounds when there is interference from environmental noise,and whether males and females display convergent behavioral responses in the face of noise masking remain poorly understood.In this study,we investigated the effects of conspecific male advertisement calls with different signal-to-noise ratios on male-male competition and female choice in the Anhui tree frog Rhacophorus zhoukaiyae using playback and phonotaxis experiments,respectively.The results showed that(1)female Anhui tree frogs preferentially selected the conspecific calls with higher SNR compared to calls with lower SNR;(2)males preferen-tially responded vocally to the conspecific calls with higher SNR compared to calls with lower SNR;and(3)males'competitive strategies were flexible in the face of noise interference.These results suggest that preferences of both sexes converge in outcome,and that male competitive strategies may depend on predictable female preferences.This study will provide an important basis for further research on decision-making in animals.
基金S.E.L. was supported by a National Science Foundation （NSF） Graduate Research Opportunities Worldwide （GROW） Fellowship in Switzerland and NSF Graduate Research Fellowship under Grant No. 1154145. Any opinion, findings, and conclusions or recommendations expressed in this material are those of the author and do not necessarily reflect the views of the NSF.
文摘Research on sexual selection and hybridization has focused on female mate choice and male-male competition. While the evolutionary outcomes of interspecific female preference have been well explored, we are now gaining a better understanding of the processes by which male-male compe- tition between species in secondary contact promotes reproductive isolation versus hybridization. What is relatively unexplored is the interaction between female choice and male competition, as they can oppose one another or align with similar outcomes for reproductive isolation. The role of female-female competition in hybridization is also not well understood, but could operate similarly to male-male competition in polyandrous and other systems where costs to heterospecific mating are low for females. Reproductive competition between either sex of sympatric species can cause the divergence and/or convergence of sexual signals and recognition, which in turn influences the likelihood for interspecific mating. Future work on species interactions in secondary contact should test the relative influences of both mate choice and competition for mates on hybridization outcomes, and should not ignore the possibilities that females can compete over mating resources, and males can exercise mate choice.
文摘Male reproductive tactics vary widely across the species of the ant genus Cardiocondyla, from obligatory lethal combat among co-occurring males to complete mutual tolerance. The African species C. venustula Wheeler, 1908 has an intermediate phylogenetic position between taxa with fighting males and taxa with tolerant males and also shows an intermediate male behavior. Males from 2 native populations in South Africa and a population introduced to Puerto Rico attacked and killed freshly eclosing rivals but rarely engaged in deadly fights with adult competitors, Instead, several males per colony established small ＂territories＂ in their natal nests and defended them against other males. Males with a stable territory had more contact with female sexuals than nonterritorial males and more frequently engaged in mating attempts. In controlled choice experiments, female sexuals did not show any preference for particular males. We suggest that male territoriality in C. venustula is an adaptation to the seasonal production of large numbers of female sexuals by multiple mothers.
文摘Natural selection has been shown to drive population differentiation and speciation. The role of sexual selection in this process is controversial; however, most of the work has centered on mate choice while the role of male-male competition in speciation is relatively understudied. Here, we outline how male-male competition can be a source of diversifying selection on male competitive phenotypes, and how this can contribute to the evolution of reproductive isolation. We highlight how negative frequency-dependent selection （advantage of rare phenotype arising from stronger male-male competition between similar male phenotypes compared with dissimilar male pheno- types） and disruptive selection （advantage of extreme phenotypes） drives the evolution of diversity in competitive traits such as weapon size, nuptial coloration, or aggressiveness. We underscore that male-male competition interacts with other life-history functions and that variable male com- petitive phenotypes may represent alternative adaptive options. In addition to competition for mates, aggressive interference competition for ecological resources can exert selection on compet- itor signals. We call for a better integration of male-male competition with ecological interference competition since both can influence the process of speciation via comparable but distinct mecha- nisms. Altogether, we present a more comprehensive framework for studying the role of male-male competition in speciation, and emphasize the need for better integration of insights gained from other fields studying the evolutionary, behavioral, and physiological consequences of agonistic interactions.
基金Permits and ethics approval to perform the research were obtained from The University of Melbourne Animal Ethics Committee(1413220.3)the South Australian Wildlife Ethics Committee(25/2015)+1 种基金the South Australian Department of Environment,Water and Natural Resources(Q26428-2)the Victorian Department of Environment,Land,Water and Planning(10007751).This work was supported by funding from the Australian Research Council(DP150101044)to D.S.-F.
文摘Diversification in sexual signals is often taken as evidenee for the importance of sexual selection in speciatio n.However,in order for sexual selection to gen erate reproductive isolati on between populations,both signals and mate preferences must diverge together.Furthermore,assortative mating may result from multiple behavioral mecha nisms,in eluding female mate pref ere nces,male mate preferences,and male-male competition;yet their relative contributions are rarely evaluated.Here,we explored the role of mate pref ere nces and male competitive ability as pote ntial barriers to gene flow between 2 diverge nt lineages of the taw ny dragon lizard,Ctenophorus decresii,which differ in male throat coloration.We found stronger behavioral barriers to pairings between southern lineage males and northern lineage females than between northern males and southern females,indicating incomplete and asymmetric behavioral isolating barriers.These results were driven by both male and female mate preferences rather than lineage differences in male competitive ability.In trasexual selecti on is therefore un likely to drive the outcome of sec on dary contact in C.decresii,despite its widely ack no wledged importa nee in lizards.Our results are consiste nt with the emergi ng view that although both male and female mate pref ere nces can diverge alongside sexual signals,speciation is rarely driven by divergent sexual selection alone.
文摘Sensory drive predicts that the conditions under which signaling takes place have large effects on signals, sensory systems, and behavior. The coupling of an ecological genetics approach with sen sory drive has been fruitful. An ecological genetics approach compares populations that experi ence different environments and asks whether population differences are adaptive and are the result of genetic and/or environmental variation. The multifaceted effects of signaling environ ments are wellexemplified by the bluefin killifish. In this system, males with blue anal fins are abundant in tanninstained swamps that lack UV/blue light but are absent in clear springs where UV/blue light is abundant. Past work indicates that lighting environments shape genetic and envir onmental variation in color patterns, visual systems, and behavior. Less is known about the select ive forces creating the across population correlations between UV/blue light and the abundance of blue males. Here, we present three new experiments that investigate the roles of lighting environ ments on male competition, female mate choice, and predation. We found strong effects of lighting environments on male competition where blue males were more likely to emerge as dominant in teastained water than in clear water. Our preliminary study on predation indicated that blue males may be less susceptible to predation in teastained water than in clear water. However, there was little evidence for female preferences favoring blue males. The resulting pattern is one where the effects of lighting environments on genetic variation and phenotypic plasticity match the direction of selection and favor the expression of blue males in swamps.
文摘Our knowledge of how male competition contributes to speciation is dominated by investigations of competition between within-species morphs or closely related species that differ in conspicuous traits expressed during the breeding season （e.g. color, song）. In such studies, it is important to consider the manner in which putatively sexually selected traits influence the outcome of competitive interactions within and between types because these traits can communicate information about competitor quality and may not be utilized by homotypic and heterotypic receivers in the same way. We studied the roles of breeding color and aggressive behaviors in competition within and between two divergent threes- pine stickleback Gasterosteus aculeatus color types. Our previous work in this system showed that the switch from red to black breeding coloration is associated with changes in male competition biases. Here, we find that red and black males also use different currencies in competition. Winners of both color types performed more aggressive behaviors than losers, regardless of whether the competitor was of the same or opposite color type. But breeding color differently predicted competitive outcomes for red and black males. Males who were redder at the start of competition were more likely to win when paired with homotypic competitors and less likely to win when paired with heterotypic competitors. In contrast, black color, though expressed in the breeding season and condition dependent, was unrelated to competitive outcomes. Placing questions about the role of male competition in speciation in a sexual signal evolution framework may provide insight into the ＂why and how＂ of aggression biases and asymmetries in competitive ability between closely related morphs and species.
基金We are grateful to L.Delbac who maintained and managed the insect stock,and M.Lebbar for its valuable experimental assistance.We also thank the two anonymous reviewers,for their relevant suggestions on the draft.This study was funded by the Conseil Regional de Bour-gogne Franche-Comte through the Plan d'Actions Regional pour I'Innovation(PARI),and the European Union through the PO FEDER-FSE Bourgogne 2014/2020 programs.
文摘Males evolved plastic strategies to respond to male-male competition and exhibit adaptive traits and behaviors maximizing their access to the females and limiting sperm competition.Mating behaviors allow males to express quick responses to current sexual audience,that is,the number of nearby conspecifics prone to mate.In contrast,physiological responses are frequently delayed because they are constrained by the time and resources having to be mobilized to produce and export sperm and associated products.This is especially critical in species for which males produce spermatophores.Here we investigated in what extend moth males(the tortricid moth Lobesia botrana)producing spermatophores exhibit plastic behavioral and physiological responses to different sexual audiences before and during mating and the consequences for their reproductive output.We found that males adjusted their mating behaviors and spermatophore size to a potentially elevated risk of sperm competition perceived before mating.In addition,males responded to the closed presence of females during mating by reducing their mating duration.Surprisingly,the various behavioral and physiological responses we highlighted here were not fully reflected in their reproductive performance as we did not reveal any effect on fecundity and fertility of their mate.The selective pressure exerted on males experiencing male-male competition could thus be sufficient to trigger adjustment in male mating behaviors but constrains physiological responses according to the perception of competition.
文摘Male-male competition and female mate choice may both play important roles in driving and maintaining reproductive isolation between species. When previously allopatric species come into secondary contact with each other due to introductions, they provide an opportunity to evaluate the identity and strength of reproductive isolating mechanisms. If reproductive isolation is not maintained, hybridization may occur. We examined how reproductive isolating mechanisms medi- ate hybridization between endemic populations of the Red River pupfish Cyprinodon rubrofluviati- lis and the recently introduced sheepshead minnow C. variegatus. In lab-based dominance trials, males of both species won the same number of competitions. However, male C. rubrofluviatilis that won competitions were more aggressive than C, variegatus winners, and more aggression was needed to win against competitor C. variagatus than allopatric C. rubrofluviatilis. Duration of fights also differed based on the relatedness of the competitor. In dichotomous mate choice trials, there were no conspecific or heterospecific preferences expressed by females of either species. Our findings that male-male aggression differs between closely and distantly related groups, but female choice does not suggest that male-male competition may be the more likely mechanism to impede gene flow in this system.
