Sexual selection and the evolution of male and female cognition: A test using experimental evolution in seed beetles*

Abstract

The mating system is thought to be important in shaping animal intelligence and sexual selection has been depicted as a driver of cognitive evolution, either directly by promoting superior cognitive ability during mate competition, or indirectly via genic capture of sexually selected traits. However, it remains unclear if intensified sexual selection leads to general improvements in cognitive abilities. Here, we evaluated this hypothesis by applying experimental evolution in seed beetles. Replicate lines, maintained for 35 generations of either enforced monogamy (eliminating sexual selection) or polygamy, were challenged to locate and discriminate among mates (male assays) or host seeds (female assays) in a spatial chemosensory learning task. All lines displayed learning between trials. Moreover, polygamous males outperformed monogamous males, providing evidence that sexual selection can lead to the evolution of improved male cognition. However, there were no differences between regimes in rates of male learning, and polygamous females showed no improvement in host search and even signs of reduced learning. Hence, sexual selection increased performance in cognitively demanding mate search, but it did not lead to general increases in cognitive abilities. We discuss the possibility that sexually antagonistic selection is an important factor maintaining abundant genetic variation in cognitive traits.

Sexual conflict drives micro- and macroevolution of sexual dimorphism in immunity

“…To directly test the hypothesis that sexual selection and conflict over mating is causing the observed sexual dimorphism in immunity in C. maculatus , we compared the levels of PO activity in males and females from replicate experimental evolution lines maintained for 27 generations under one of three alternative mating regimes; natural polygamy (natural selection and sexual selection – multiple mating); enforced monogamy (natural selection but excluding sexual selection – single mating); and male-limited selection (applying sexual selection but relaxing natural selection–multiple mating but female coevolution to reduce male harm prevented). The lines are further described in the Methods section and in (63,88,89). We predicted that females from polygamous lines that had evolved under frequent multiple mating would invest more in PO activity than females from monogamous lines, while the male-limited lines reveal the extent to which female PO activity may change in the polygamous mating system via genetic correlation when selection acts mainly via males.…”

“…There are three replicate "Monogamy" lines, three "Polygamy" lines and two replicate to monogamy lines at generations 16 and 20, respectively (45). They also show differences in sexually selected male pre-and post-copulatory traits (67,95).…”

Digest: Sexual selection and evolution of cognition in seed beetles*

“…However, cognitive ability is sometimes not expressed phenotypically during mate choice and acquisition, thus preventing its direct sexual selection. It remains unclear if the sexual selection of other traits elicits pleiotropic effects required for the indirect sexual selection, and subsequent evolution, of cognitive ability (Baur et al., ).…”

“…In this issue, Baur et al. () experimentally test whether sexual selection can drive cognitive evolution using Callosobruchus maculatus seed beetles. Sexual selection was manipulated by enforcing either monogamy (sexual selection removed) or polygamy (naturally high levels of sexual selection) for 35 generations.…”

“…The research by Baur et al. () demonstrates that cognitive ability can evolve through sexual selection in C. maculatus . In addition, it shows how standing genetic variation in this trait can be maintained by balancing selection arising from sexual antagonism and antagonistic pleiotropy.…”