Brain size and weight vary tremendously in the animal kingdom. It has been suggested that brain structural develop- ment must evolve balanced between the advantages of dealing with greater social challenges mad the en...Brain size and weight vary tremendously in the animal kingdom. It has been suggested that brain structural develop- ment must evolve balanced between the advantages of dealing with greater social challenges mad the energetic costs of maintain- ing and developing larger brains. Here we ask if interspecific differences in cooperative behaviour （i.e. cleaning behaviour） are related to brain weight variations in four close-related species of Labrid fish： two are obligatory cleanerfish throughout their en- tire life （Labroides dimidiatus and L. bicolor）, one facultative cleaner fish Labropsis australis and one last species that never en- gage in cleaning Labrichthys unilineatus. We first search for the link between the rate of species＇ cooperation and its relative brain weight, and finally, if the degree of social complexity and cooperation are reflected in the weight of its major brain sub- structures. Overall, no differences were found in relative brain weight （in relation to body weight） across species. Fine-scale dif- ferences were solely demonstrated for the facultative cleaner L. australis, at the brainstem level. Furthermore, data visual exami- nation indicates that the average cerebellum and brainstem weights appear to be larger for L. dimidiatus. Because variation was solely found at specific brain areas （such as cerebellum and brainstem） and not for the whole brain weight values, it suggests that species social-ecological and cognitive demands may be directly contributing to a selective investment in relevant brain areas. This study provides first preliminary evidence that links potential differences in cognitive ability in cooperative behaviour to how these may mediate the evolution of brain structural development in non-mammal vertebrate groups .展开更多
Sexual imprinting is a common mechanism of mate preference learning. It is thought to influence how traits evolve and in some cases to promote speciation. Recently there has been increasing interest in how sexual impr...Sexual imprinting is a common mechanism of mate preference learning. It is thought to influence how traits evolve and in some cases to promote speciation. Recently there has been increasing interest in how sexual imprinting itself evolves. Theoretical work on polygynous mating systems predicts that females will evolve paternal imprinting, which means they learn to prefer phenotypes expressed by their fathers. In nature however, females of some species learn to prefer phenotypes expressed by their mothers instead. We used a dynamical systems model and tools from adaptive dynamics to study how sexual imprinting evolves in species with socially monogamous mating systems. We considered cases in which the target trait for imprinting is un- der viability selection but is not a reliable signal of paternal investment. Thus, the target trait signals the genetic benefits rather than the parental care benefits of mate choice. When mating is socially monogamous and there is some extra-pair patemity, we show that maternal imprinting can be favored over paternal imprinting. Counterintuitively, females often become choosier when selecting social partners in systems where extra-pair mating is more frequent. That is, females may be more selective when choosing social partners that will sire a smaller percentage of their offspring. Our results offer new testable hypotheses, and ad- vance our understanding of the mechanisms that drive the evolution of mate choice strategies in nature .展开更多
文摘Brain size and weight vary tremendously in the animal kingdom. It has been suggested that brain structural develop- ment must evolve balanced between the advantages of dealing with greater social challenges mad the energetic costs of maintain- ing and developing larger brains. Here we ask if interspecific differences in cooperative behaviour （i.e. cleaning behaviour） are related to brain weight variations in four close-related species of Labrid fish： two are obligatory cleanerfish throughout their en- tire life （Labroides dimidiatus and L. bicolor）, one facultative cleaner fish Labropsis australis and one last species that never en- gage in cleaning Labrichthys unilineatus. We first search for the link between the rate of species＇ cooperation and its relative brain weight, and finally, if the degree of social complexity and cooperation are reflected in the weight of its major brain sub- structures. Overall, no differences were found in relative brain weight （in relation to body weight） across species. Fine-scale dif- ferences were solely demonstrated for the facultative cleaner L. australis, at the brainstem level. Furthermore, data visual exami- nation indicates that the average cerebellum and brainstem weights appear to be larger for L. dimidiatus. Because variation was solely found at specific brain areas （such as cerebellum and brainstem） and not for the whole brain weight values, it suggests that species social-ecological and cognitive demands may be directly contributing to a selective investment in relevant brain areas. This study provides first preliminary evidence that links potential differences in cognitive ability in cooperative behaviour to how these may mediate the evolution of brain structural development in non-mammal vertebrate groups .
文摘Sexual imprinting is a common mechanism of mate preference learning. It is thought to influence how traits evolve and in some cases to promote speciation. Recently there has been increasing interest in how sexual imprinting itself evolves. Theoretical work on polygynous mating systems predicts that females will evolve paternal imprinting, which means they learn to prefer phenotypes expressed by their fathers. In nature however, females of some species learn to prefer phenotypes expressed by their mothers instead. We used a dynamical systems model and tools from adaptive dynamics to study how sexual imprinting evolves in species with socially monogamous mating systems. We considered cases in which the target trait for imprinting is un- der viability selection but is not a reliable signal of paternal investment. Thus, the target trait signals the genetic benefits rather than the parental care benefits of mate choice. When mating is socially monogamous and there is some extra-pair patemity, we show that maternal imprinting can be favored over paternal imprinting. Counterintuitively, females often become choosier when selecting social partners in systems where extra-pair mating is more frequent. That is, females may be more selective when choosing social partners that will sire a smaller percentage of their offspring. Our results offer new testable hypotheses, and ad- vance our understanding of the mechanisms that drive the evolution of mate choice strategies in nature .
