Diferenças inter e intrassexuais na aprendizagem espacial de um peixe amazônico sexualmente dimórfico

Abstract

The individual processes of acquisition, retention and use of information to solve cognitive tasks can vary between individuals. Such cognitive variation may be explained by consistent behavioral differences, resulting from sexual dimorphism or morphological variations within a single sex. This can generate different susceptibilities to predation in individuals with higher degree of ornamentation, and/or mating preference for individuals with enhanced cognitive skills, which contributes to the evolution of cognition. In that context, when selective pressures act differently among individuals, variations in ecologically relevant decision-making are expected. Additionally, a functional link between individual cognitive variation and animal personality is suggested, generating speed-accuracy trade-offs. In a further step, we investigated the relationship between spatial learning to male ornamental degree and neophobia and finally female mate choice, in the Amazonian fish Crenuchus spilurus, a sexually dimorphic species. We found no sex differences in the learning rate of the spatial task. However, when assessing males’s individual differences, those with higher degree of ornamentation showed better performance in the learning task, displaying greater precision to solve the maze on the last day of test. The performance of these males was better than males with lower degree of ornamentation and females. Males with a higher degree of ornamentation were more neophobic and took longer to resolve the spatial task on the first attempt. This suggests that males with a higher degree of ornamentation behave according to the asset-protection principle, which proposes that more attractive males should be more cautious as a result of higher future returns consequences of their physical characteristics. In addition, females showed preference for males with higher degree of ornamentation, which consequently, were also the individuals who showed better performance in learning the spatial task. We propose that the sex differences in cognition can emerge from the intrassexual variation, caused by the selective pressure that occurs in males with higher degree of ornamentation. Additionally, as the asset-protection principle stems from the pressure of predation, sexual selection through female mate choice provides an exchange of rewards and risks, on which natural selection acts indirectly by increasing learning skills.