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
Ultraviolet(UV)A signals(320-400 nm)are important in mate choice in numerous species.The sensitivity for UV signals is not only assumed to be costly,but also expected to be a function of the prevailing ecological cond...Ultraviolet(UV)A signals(320-400 nm)are important in mate choice in numerous species.The sensitivity for UV signals is not only assumed to be costly,but also expected to be a function of the prevailing ecological conditions.Generally,those signals are favored by selection that efficiently reach the receiver.A decisive factor for color signaling is the lighting environment,especially in aquatic habitats,as the visibility of signals,and thus costs and benefits,are instantaneously influenced by it.Although ecological aspects of color signal evolution are relatively well-studied,there is little data on specific effects of environmental UV-light conditions on signaling at these shorter wavelengths.We studied wild-caught gravid female 3-spined sticklebacks Gasterosteus aculeatus of 2 photic habitat types(tea-stained and clear-water lakes),possessing great variation in their UV transmission.In 2 treatments,tea-stained and clear-water,preferences for males viewed under UV-present(UV-1-)and UV-absent(UV-)conditions were tested.A preference for males under UV+conditions was found for females from both habitat types,thus stressing the significance of UV signals in stickleback's mate choice decisions.However,females from both habitat types showed the most pronounced preferences for males under UV-h conditions under clear-water test conditions.Moreover,reflectance measurements revealed that the carotenoid-based orange-red breeding coloration in wild-caught males of both habitat types differed significantly in color intensity(higher in clear-water males)and hue(more red shifted in clear-water males)while no significant differences in UV coloration were found.The differential reflection patterns in longer wavelengths suggest that sticklebacks of both habitat types have adapted to the respective water conditions.Adaptations of UV signals in a sexual context to ambient light conditions in both behavior and coloration seem less evident.展开更多
Different environmental conditions may lead to diverse morphological,behavioral,and physiological adaptations of different populations of the same species.Lighting conditions,for example,vary vastly especially between...Different environmental conditions may lead to diverse morphological,behavioral,and physiological adaptations of different populations of the same species.Lighting conditions,for example,vary vastly especially between aquatic habitats,and have been shown to elicit adaptations.The availability of short-wave ultraviolet(UV)light is especially fluctuating,as UV wavelengths are attenuated strongly depending on water properties.The island of North Uist,Scotland,comprises 2 differential habitat types,tea-stained and clear-water lakes,varying considerably in UV transmission.In previous studies,wild-caught 3-spined stickleback Gasterosteus aculeatus populations(3 populations of each habitat type)were tested with respect to their shoaling and mate preferences for fish viewed under UV-present and UV-absent conditions.The results revealed a habitat-dependent preference of UV cues during shoal choice(tea-stained populations:preference for UV-absent condition in tea-stained water;clear-water populations:no preference in clear-water)but an overall preference for UV-present conditions during mate choice.To assess genetic influences on these behavioral patterns,similar experiments were conducted with lab-bred F1-gen-erations of the same stickleback populations that were raised in a common environment(i.e.standardized clear-water conditions).Offspring of sticklebacks from tea-stained lakes tended to prefer shoals viewed under UV-absent conditions(only in tea-stained water),while sticklebacks from clear-water lakes showed a significant preference for the shoal viewed under UV-present conditions in clear-water but not in tea-stained water.Mate-preference experiments demonstrated that females from the tea-stained lakes significantly preferred and females from the clear-water lakes preferred by trend the male viewed under UV-present conditions in the clear-water treatment.The results for both shoaling-and mate-preference tests were largely similar for wild-caught and lab-bred sticklebacks,thus hinting at a genetic basis for the preference patterns.展开更多
Despite growing interest in female ornament evolution, we still have a rudimentary understanding of female display traits relative to similar traits in males. Under one popular adaptive scenario, female ornaments are ...Despite growing interest in female ornament evolution, we still have a rudimentary understanding of female display traits relative to similar traits in males. Under one popular adaptive scenario, female ornaments are hypothesized to function in female-female competition and serve as badges of status, such that their expression is linked with elevated aggression in some cases. In this study, we investigated the relationship between 2 female ornaments--male-like red throat color and red spine coloration--and female aggression in 2 independently derived stream-resident populations of three-spined stickleback Gasterosteus aculeatus. Using simulated intrusions, we tested whether females with redder ornaments were generally more aggressive, and for variation in aggressive and social behaviors between the 2 populations. We found that the red intensity of the throat and spine did not predict aggression levels in either population, suggesting a limited role for both female ornaments during female-female interaction. The 2 populations exhibited different levels of aggressive behaviors, unrelated to the color patches. Our results suggest that variation in selective pressures between populations may promote interpopulation variance in aggressive behavior but not the correlation between female ornamentation and aggression, and raise the possibility that red coloration may have evolved through different mechanisms or processes in the 2 populations.展开更多
Many animals are sensitive to ultraviolet light and also possess UV-reflective regions on their body surface. Individu- als reflecting UV have been shown to be preferred during social interactions such as mate choice ...Many animals are sensitive to ultraviolet light and also possess UV-reflective regions on their body surface. Individu- als reflecting UV have been shown to be preferred during social interactions such as mate choice or shoaling decisions. However, whether those body UV-reflections enhance also the conspicuousness to UV-sensitive predators and thereforeentail costs for its bearer is less well documented. Two size-matched three-spined sticklebacks Gasterosteus aculeatus, one enclosed in a UV-transmitting （UV＋） and another in a UV-blocking （UV-） chamber, were simultaneously presented to individual brown trout Salmo trutta. ＂yearlings＂. Brown trout of this age are sensitive to the UV part of the electromagnetic spectnun and are natural predators of three-spined sticklebacks. The stickleback that was attacked first as well as the subsequent number of attacks was recorded. Sticklebacks enclosed in the UV-transmitting chamber were attacked first significantly more often compared to stickle- backs enclosed in the UV-blocking chamber. Control experiments using neutral density filters revealed that this was more likely due to LrV having an influence on hue perception rather than brighmess discrimination. The difference in attack probability cor- responded to the difference in chromatic contrasts between sticklebacks and the experimental background calculated for both the UV＋ and UV- conditions in a physiological model of trout colour vision. UV reflections seem to be costly by enhancing the risk of predation due to an increased conspicuousness of prey. This is the first study in a vertebrate, to our knowledge, demonstrating direct predation risk due to UV wavelengths [Current Zoology 59 （2）： 151-159, 2013].展开更多
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This research was funded by the Deutsche Forschungsgemeinschaft(BA 2885/1-5).
文摘Ultraviolet(UV)A signals(320-400 nm)are important in mate choice in numerous species.The sensitivity for UV signals is not only assumed to be costly,but also expected to be a function of the prevailing ecological conditions.Generally,those signals are favored by selection that efficiently reach the receiver.A decisive factor for color signaling is the lighting environment,especially in aquatic habitats,as the visibility of signals,and thus costs and benefits,are instantaneously influenced by it.Although ecological aspects of color signal evolution are relatively well-studied,there is little data on specific effects of environmental UV-light conditions on signaling at these shorter wavelengths.We studied wild-caught gravid female 3-spined sticklebacks Gasterosteus aculeatus of 2 photic habitat types(tea-stained and clear-water lakes),possessing great variation in their UV transmission.In 2 treatments,tea-stained and clear-water,preferences for males viewed under UV-present(UV-1-)and UV-absent(UV-)conditions were tested.A preference for males under UV+conditions was found for females from both habitat types,thus stressing the significance of UV signals in stickleback's mate choice decisions.However,females from both habitat types showed the most pronounced preferences for males under UV-h conditions under clear-water test conditions.Moreover,reflectance measurements revealed that the carotenoid-based orange-red breeding coloration in wild-caught males of both habitat types differed significantly in color intensity(higher in clear-water males)and hue(more red shifted in clear-water males)while no significant differences in UV coloration were found.The differential reflection patterns in longer wavelengths suggest that sticklebacks of both habitat types have adapted to the respective water conditions.Adaptations of UV signals in a sexual context to ambient light conditions in both behavior and coloration seem less evident.
基金This research was funded by the Deutsche Forschungsgemeinschaft(DFG)(BA 2885/1-5).
文摘Different environmental conditions may lead to diverse morphological,behavioral,and physiological adaptations of different populations of the same species.Lighting conditions,for example,vary vastly especially between aquatic habitats,and have been shown to elicit adaptations.The availability of short-wave ultraviolet(UV)light is especially fluctuating,as UV wavelengths are attenuated strongly depending on water properties.The island of North Uist,Scotland,comprises 2 differential habitat types,tea-stained and clear-water lakes,varying considerably in UV transmission.In previous studies,wild-caught 3-spined stickleback Gasterosteus aculeatus populations(3 populations of each habitat type)were tested with respect to their shoaling and mate preferences for fish viewed under UV-present and UV-absent conditions.The results revealed a habitat-dependent preference of UV cues during shoal choice(tea-stained populations:preference for UV-absent condition in tea-stained water;clear-water populations:no preference in clear-water)but an overall preference for UV-present conditions during mate choice.To assess genetic influences on these behavioral patterns,similar experiments were conducted with lab-bred F1-gen-erations of the same stickleback populations that were raised in a common environment(i.e.standardized clear-water conditions).Offspring of sticklebacks from tea-stained lakes tended to prefer shoals viewed under UV-absent conditions(only in tea-stained water),while sticklebacks from clear-water lakes showed a significant preference for the shoal viewed under UV-present conditions in clear-water but not in tea-stained water.Mate-preference experiments demonstrated that females from the tea-stained lakes significantly preferred and females from the clear-water lakes preferred by trend the male viewed under UV-present conditions in the clear-water treatment.The results for both shoaling-and mate-preference tests were largely similar for wild-caught and lab-bred sticklebacks,thus hinting at a genetic basis for the preference patterns.
文摘Despite growing interest in female ornament evolution, we still have a rudimentary understanding of female display traits relative to similar traits in males. Under one popular adaptive scenario, female ornaments are hypothesized to function in female-female competition and serve as badges of status, such that their expression is linked with elevated aggression in some cases. In this study, we investigated the relationship between 2 female ornaments--male-like red throat color and red spine coloration--and female aggression in 2 independently derived stream-resident populations of three-spined stickleback Gasterosteus aculeatus. Using simulated intrusions, we tested whether females with redder ornaments were generally more aggressive, and for variation in aggressive and social behaviors between the 2 populations. We found that the red intensity of the throat and spine did not predict aggression levels in either population, suggesting a limited role for both female ornaments during female-female interaction. The 2 populations exhibited different levels of aggressive behaviors, unrelated to the color patches. Our results suggest that variation in selective pressures between populations may promote interpopulation variance in aggressive behavior but not the correlation between female ornamentation and aggression, and raise the possibility that red coloration may have evolved through different mechanisms or processes in the 2 populations.
文摘Many animals are sensitive to ultraviolet light and also possess UV-reflective regions on their body surface. Individu- als reflecting UV have been shown to be preferred during social interactions such as mate choice or shoaling decisions. However, whether those body UV-reflections enhance also the conspicuousness to UV-sensitive predators and thereforeentail costs for its bearer is less well documented. Two size-matched three-spined sticklebacks Gasterosteus aculeatus, one enclosed in a UV-transmitting （UV＋） and another in a UV-blocking （UV-） chamber, were simultaneously presented to individual brown trout Salmo trutta. ＂yearlings＂. Brown trout of this age are sensitive to the UV part of the electromagnetic spectnun and are natural predators of three-spined sticklebacks. The stickleback that was attacked first as well as the subsequent number of attacks was recorded. Sticklebacks enclosed in the UV-transmitting chamber were attacked first significantly more often compared to stickle- backs enclosed in the UV-blocking chamber. Control experiments using neutral density filters revealed that this was more likely due to LrV having an influence on hue perception rather than brighmess discrimination. The difference in attack probability cor- responded to the difference in chromatic contrasts between sticklebacks and the experimental background calculated for both the UV＋ and UV- conditions in a physiological model of trout colour vision. UV reflections seem to be costly by enhancing the risk of predation due to an increased conspicuousness of prey. This is the first study in a vertebrate, to our knowledge, demonstrating direct predation risk due to UV wavelengths [Current Zoology 59 （2）： 151-159, 2013].
