Experimental evolution reveals differential evolutionary trajectories in male and female activity levels in response to sexual selection and metapopulation structure

Abstract

Behavior is central to interactions with the environment and thus has significant consequences for individual fitness. Sexual selection and demographic processes have been shown to independently shape behavioral evolution. Although some studies have tested the simultaneous effects of these forces, no studies have investigated their interplay in behavioral evolution. We applied experimental evolution in the seed beetle Callosobruchus maculatus to investigate, for the first time, the interactive effects of sexual selection intensity (high [polygamy] vs. minimal [enforced monogamy]) and metapopulation structure (yes/no) on the evolution of movement activity, a crucial behavior involved in multiples functions (e.g., dispersal, predator avoidance, or resource acquisition) and thus, closely related to fitness. We found that the interactive effects of the selection regimes did not affect individual activity, which was assayed under two different environments (absence vs. presence of conspecific cues from both sexes). However, contrasting selection regimes led to sex‐ and context‐dependent divergence in activity. The relaxation of sexual selection favored an increase in female, but not male, movement activity that was consistent between environmental contexts. In contrast, selection associated with the presence/absence of metapopulation structure led to context‐dependent responses only in male activity. In environments containing cues from conspecifics, males from selection lines under population subdivision showed increased levels of activity compared to those assayed in an environment devoid of conspecifics cues, whereas the opposite was true for males from panmictic lines. These results underscore that both the effects of sexual selection and population spatial structure may be crucial in shaping sex‐specific behavioral evolution.

Pesticide exposure triggers sex-specific inter- and transgenerational effects conditioned by past sexual selection

“…Population size for each of the selection lines has been kept constant to avoid undesired effects arising from genetic drift (50 founding individuals, 25 females and 25 males, for every population and generation). Full details of the experimental evolution protocol and its expected impact on the selective forces (intensity of sexual selection, softness of selection and scope for fecundity selection) acting on the replicated populations from the different selection regimes are provided in Rodriguez-Exposito & Garcia-Gonzalez [43] and Canal et al [44].…”

“…Full details of the experimental evolution protocol and its expected impact on the selective forces (intensity of sexual selection, softness of selection and scope for fecundity selection) acting on the replicated populations from the different selection regimes are provided in Rodriguez-Exposito & Garcia-Gonzalez [ 43 ] and Canal et al . [ 44 ].…”

“…All covariates were included as control predictors, and so random slopes were not modelled, as interactions between these control predictors and the treatments were not present in the model (they were not the focus of the analyses), and this procedure is expected not to inflate type I errors [ 61 ]. To ease the interpretation of results and also because in this species males and females have distinct life histories [ 44 , 62 ], we conducted the analyses separately for each sex of the focal individual, and by the sex of the parent/grandparent (for F1 and F2, respectively) initially exposed to treatment.…”

“…To test this idea, we capitalize on our ongoing work using populations of C. maculatus that have experimentally evolved under strong versus relaxed sexual selection and sexual conflict [ 43 ]. These C. maculatus selection lines were raised under either enforced monogamy or unrestricted polygamy for over 84 generations, therefore, imposing relaxed versus strong sexual selection, respectively [ 43 , 44 ]. In a previous study, we confirmed that non-lethal concentrations of the pesticide deltamethrin trigger transgenerational effects in a population of C. maculatus [ 38 ].…”