Mate-choice copying is a fascinating and widespread mate-choice strategy. Individuals gather public information about potential mates by observing others during sexual interactions and choose or reject the same indivi...Mate-choice copying is a fascinating and widespread mate-choice strategy. Individuals gather public information about potential mates by observing others during sexual interactions and choose or reject the same individual as a mate as the observed individual did before. The influence of copying behavior on an individual＇s mate choice can be so strong that socially acquired information can override genetically based preferences for certain phenotypes. Thus, mate-choice copying enforces dy- namic processes in sexual selection. Here, we review the current state of research on mate-choice copying and focus on sex-specific aspects. We present evidence that mate-choice copying can support the evolution of novel sexual ornaments, and we discuss potential costs of mate-choice copying when public information is not reliable. Moreover, we discuss the conflict faced by males that copy since mate-choice copying increases sperm competition. In conclusion we suggest interesting topics for future research in mate-choice copying .展开更多
Recent studies have revealed that sexually selected traits may signal sperm quality and hence male fertilisation ability. There is also evidence that the expression of male sexual ornamentation and associated sperm ch...Recent studies have revealed that sexually selected traits may signal sperm quality and hence male fertilisation ability. There is also evidence that the expression of male sexual ornamentation and associated sperm characteristics depend on an indi- vidual＇s ability to cope with oxidative stress. Carotenoids are known for their antioxidant properties and carotenoid-based orna- ments might represent honest signals as these pigments can be traded offbetween the investment in sexual ornamentation, sperm function as well as immune response. In this study, we examined the relationship between sexual ornamentation （breeding colo- ration） and sperm characteristics （e.g., velocity and morphology） in the three-spined stickleback Gasterosteus aeuleatus, an ex- ternally fertilising fish species, in which sperm competition commonly occurs. During the breeding season males are sperm limi- ted and develop a conspicuous carotenoid-based coloration, which is under strong pre-copulatory sexual selection due to female mate choice and male-male competition. The results of the present study show that the expression of stickleback male breeding coloration is significantly positively associated with the linearity of sperm movement, whereas sperm morphology （head length to tail length ratio） is significantly negatively related to the trajectory of sperm movement. Moreover, there is some support for the phenotype-linked fertility hypothesis as the intensity of male red breeding coloration is significantly positively correlated with sperm velocity, which is supposed to be an important determinant of fertilisation success in external fertilisers, indicating the honesty of the sexually selected nuptial red coloration.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
Multidirectional communicative interactions in social networks can have a profound effect on mate choice behavior. Male Atlantic molly Poecilia mexicana exhibit weaker mating preferences when an audience male is prese...Multidirectional communicative interactions in social networks can have a profound effect on mate choice behavior. Male Atlantic molly Poecilia mexicana exhibit weaker mating preferences when an audience male is presented. This could be a male strategy to reduce sperm competition risk： interacting more equally with different females may be advantageous because ri- vals might copy mate choice decisions. In line with this hypothesis, a previous study found males to show a strong audience effect when being observed while exercising mate choice, but not when the rival was presented only before the choice tests. Audience effects on mate choice decisions have been quantified in poeciliid fishes using association preference designs, but it remains un- known if patterns found from measuring association times translate into actual mating behavior. Thus, we created five audience treatments simulating different forms of perceived sperm competition risk and determined focal males＇ mating preferences by scoring pre-mating （nipping） and mating behavior （gonopodial thrusting）. Nipping did not reflect the pattern that was found when association preferences were measured, while a very similar pattern was uncovered in thrusting behavior. The strongest response was observed when the audience could eavesdrop on the focal male＇s behavior. A reduction in the strength of focal males＇ preferences was also seen after the rival male had an opportunity to mate with the focal male＇s preferred mate. In comparison, the reduction of mating preferences in response to an audience was greater when measuring association times than actual mating behavior. While measuring direct sexual interactions between the focal male and both slimulus females not only the male＇s motivational state is reflected but also females＇ behavior such as avoidance of male sexual harassment [Current Zoology 58 （1）： 84-94, 2012].展开更多
Variations in male body size are known to affect inter- and intrasexual selection outcomes in a wide range of animals. In mating systems involving sexual signaling before mating, body size often acts as a key factor a...Variations in male body size are known to affect inter- and intrasexual selection outcomes in a wide range of animals. In mating systems involving sexual signaling before mating, body size often acts as a key factor affecting signal strength and mate choice. We evaluated the effect of male size on courtship displays and mating success of the olive fruit fly, Bactrocera oleae （Diptera： Tephritidae）. Wing vibrations performed during successful and unsuccessful courtships by large and small males were recorded by high-speed videos and analyzed through frame-by-frame analysis. Mating success of large and small males was investigated. The effect of male-male competition on mating success was evaluated. Male body size affected both male courtship signals and mating outcomes. Successful males showed wing-borne signals with high frequencies and short interpulse intervals. Wing vibrations displayed by successful large males during copulation attempt had higher frequencies over smaller males and unsuccessful large males. In no-competition conditions, large males achieved higher mating success with respect to smaller ones. Allowing large and small males to compete for a female, large males achieve more mating success over smaller ones. Mate choice by females may be based on selection of the larger males, able to produce high-frequency wing vibrations. Such traits may be indicative of ＂good genes,＂ which under sexual selection could means good social-interaction genes, or a good competitive manipulator of conspecifics.展开更多
Local mate competition theory predicts that offspring sex ratio in pollinating fig wasps is female-biased when there is only one foundress, and increased foundress density results in increased offspring sex ratio. Inf...Local mate competition theory predicts that offspring sex ratio in pollinating fig wasps is female-biased when there is only one foundress, and increased foundress density results in increased offspring sex ratio. Information of other foundresses and clutch size have been suggested to be the main proximate explanations for sex ratio adjustment under local mate competition. Our focus was to show the mechanism of sex ratio adjustment in a pollinating fig wasp, Ceratosolen solmsi Mayr, an obligate pollinator of the functionally dioecious fig, Ficus hispida Linn., with controlled experiments in the field. First, we obtained offspring from one pollinator and offspring at different oviposition sequences, and found that offspring sex ratio decreased with clutch size, and pollinators produced most of their male offspring at the start of bouts, followed by mostly females. Second, we found that offspring sex ratio increased with foundress density, and pollinators did adjust their offspring sex ratio to other females in the oviposition patches. We suggest that when oviposition sites are not limited, pollinators will mainly adjust their offspring sex ratio to other foundresses independent of clutch size changes, whereas adjusting clutch size may be used to adjust sex ratio when oviposition sites are limited.展开更多
文摘Mate-choice copying is a fascinating and widespread mate-choice strategy. Individuals gather public information about potential mates by observing others during sexual interactions and choose or reject the same individual as a mate as the observed individual did before. The influence of copying behavior on an individual＇s mate choice can be so strong that socially acquired information can override genetically based preferences for certain phenotypes. Thus, mate-choice copying enforces dy- namic processes in sexual selection. Here, we review the current state of research on mate-choice copying and focus on sex-specific aspects. We present evidence that mate-choice copying can support the evolution of novel sexual ornaments, and we discuss potential costs of mate-choice copying when public information is not reliable. Moreover, we discuss the conflict faced by males that copy since mate-choice copying increases sperm competition. In conclusion we suggest interesting topics for future research in mate-choice copying .
文摘Recent studies have revealed that sexually selected traits may signal sperm quality and hence male fertilisation ability. There is also evidence that the expression of male sexual ornamentation and associated sperm characteristics depend on an indi- vidual＇s ability to cope with oxidative stress. Carotenoids are known for their antioxidant properties and carotenoid-based orna- ments might represent honest signals as these pigments can be traded offbetween the investment in sexual ornamentation, sperm function as well as immune response. In this study, we examined the relationship between sexual ornamentation （breeding colo- ration） and sperm characteristics （e.g., velocity and morphology） in the three-spined stickleback Gasterosteus aeuleatus, an ex- ternally fertilising fish species, in which sperm competition commonly occurs. During the breeding season males are sperm limi- ted and develop a conspicuous carotenoid-based coloration, which is under strong pre-copulatory sexual selection due to female mate choice and male-male competition. The results of the present study show that the expression of stickleback male breeding coloration is significantly positively associated with the linearity of sperm movement, whereas sperm morphology （head length to tail length ratio） is significantly negatively related to the trajectory of sperm movement. Moreover, there is some support for the phenotype-linked fertility hypothesis as the intensity of male red breeding coloration is significantly positively correlated with sperm velocity, which is supposed to be an important determinant of fertilisation success in external fertilisers, indicating the honesty of the sexually selected nuptial red coloration.
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.
文摘Multidirectional communicative interactions in social networks can have a profound effect on mate choice behavior. Male Atlantic molly Poecilia mexicana exhibit weaker mating preferences when an audience male is presented. This could be a male strategy to reduce sperm competition risk： interacting more equally with different females may be advantageous because ri- vals might copy mate choice decisions. In line with this hypothesis, a previous study found males to show a strong audience effect when being observed while exercising mate choice, but not when the rival was presented only before the choice tests. Audience effects on mate choice decisions have been quantified in poeciliid fishes using association preference designs, but it remains un- known if patterns found from measuring association times translate into actual mating behavior. Thus, we created five audience treatments simulating different forms of perceived sperm competition risk and determined focal males＇ mating preferences by scoring pre-mating （nipping） and mating behavior （gonopodial thrusting）. Nipping did not reflect the pattern that was found when association preferences were measured, while a very similar pattern was uncovered in thrusting behavior. The strongest response was observed when the audience could eavesdrop on the focal male＇s behavior. A reduction in the strength of focal males＇ preferences was also seen after the rival male had an opportunity to mate with the focal male＇s preferred mate. In comparison, the reduction of mating preferences in response to an audience was greater when measuring association times than actual mating behavior. While measuring direct sexual interactions between the focal male and both slimulus females not only the male＇s motivational state is reflected but also females＇ behavior such as avoidance of male sexual harassment [Current Zoology 58 （1）： 84-94, 2012].
文摘Variations in male body size are known to affect inter- and intrasexual selection outcomes in a wide range of animals. In mating systems involving sexual signaling before mating, body size often acts as a key factor affecting signal strength and mate choice. We evaluated the effect of male size on courtship displays and mating success of the olive fruit fly, Bactrocera oleae （Diptera： Tephritidae）. Wing vibrations performed during successful and unsuccessful courtships by large and small males were recorded by high-speed videos and analyzed through frame-by-frame analysis. Mating success of large and small males was investigated. The effect of male-male competition on mating success was evaluated. Male body size affected both male courtship signals and mating outcomes. Successful males showed wing-borne signals with high frequencies and short interpulse intervals. Wing vibrations displayed by successful large males during copulation attempt had higher frequencies over smaller males and unsuccessful large males. In no-competition conditions, large males achieved higher mating success with respect to smaller ones. Allowing large and small males to compete for a female, large males achieve more mating success over smaller ones. Mate choice by females may be based on selection of the larger males, able to produce high-frequency wing vibrations. Such traits may be indicative of ＂good genes,＂ which under sexual selection could means good social-interaction genes, or a good competitive manipulator of conspecifics.
文摘Local mate competition theory predicts that offspring sex ratio in pollinating fig wasps is female-biased when there is only one foundress, and increased foundress density results in increased offspring sex ratio. Information of other foundresses and clutch size have been suggested to be the main proximate explanations for sex ratio adjustment under local mate competition. Our focus was to show the mechanism of sex ratio adjustment in a pollinating fig wasp, Ceratosolen solmsi Mayr, an obligate pollinator of the functionally dioecious fig, Ficus hispida Linn., with controlled experiments in the field. First, we obtained offspring from one pollinator and offspring at different oviposition sequences, and found that offspring sex ratio decreased with clutch size, and pollinators produced most of their male offspring at the start of bouts, followed by mostly females. Second, we found that offspring sex ratio increased with foundress density, and pollinators did adjust their offspring sex ratio to other females in the oviposition patches. We suggest that when oviposition sites are not limited, pollinators will mainly adjust their offspring sex ratio to other foundresses independent of clutch size changes, whereas adjusting clutch size may be used to adjust sex ratio when oviposition sites are limited.
