Courtship is associated with greater spatial cognition and decreased boldness in a swordtail fish

Abstract

Alternative reproductive tactics (ARTs) offer a unique window into how sexual selection can shape cognition and nonreproductive behaviour. Sexual selection more broadly has been shown to shape cognitive traits but has rarely been investigated in the context of ARTs. Furthermore, the divergent morphology and sexual behaviour associated with ARTs may lead to different socioecological challenges (e.g. predation, space use) that further shape nonreproductive behaviours. We take advantage of the behavioural diversity in alternative reproductive tactics among male El Abra swordtails, Xiphophorus nigrensis, to ask how cognition and behaviour diverge between male tactics. We tested courting (large), coercive (small) and mixed-strategy (intermediate-sized) male phenotypes in four assays to evaluate boldness, aggression, exploration, spatial learning and spatiotemporal learning. We found that the courting-only large male phenotype had faster latencies to the reward in the spatial learning assay than the other two male phenotypes and also had greater accuracy than chance. Furthermore, we found that courting phenotypes (large and intermediate-sized males) had greater increases in accuracy over successive trials than the coercive-only small male phenotype. We also found that small, coercive male phenotypes were bolder than large and intermediate-sized males. We found no differences in aggressive behaviour (directed at a mirror) or spatiotemporal learning (shuttle box assay) across the three phenotypes. We suggest that courting males' superior spatial learning abilities may reflect their defence of females at ephemeral foraging patches as well as their need for reliable escape routes from predators. Coercive males' increased boldness may bolster their persistent behaviour and reflect reduced predation pressure. These results suggest that sexual selection for alternative reproductive strategies affects nonreproductive behaviour and cognition in directions that may align with divergent socioecological challenges associated with each mating type.