Male activity under risk predicts paternal care and reproductive success in a bi-parental cichlid

Here, we explored a hypothesis from a framework proposing that sexual
selection plays a role in shaping and maintaining consistent
among-individual behavioral variation, commonly referred to as personality
differences. This framework suggests that parental care may be a mechanism
linking personality differences with reproductive fitness. To test this
hypothesis, we repeatedly measured boldness as activity under simulated
predation risk in male and female rainbow kribs, Pelvicachromis pulcher, a
bi-parental West African cichlid. We then formed breeding pairs with
varying degrees of behavioral contrast, recorded parental care (parental
activity under risk and brood guarding) for both parents, and assessed key
reproductive outcomes: the likelihood to reproduce, clutch size, offspring
survival, and offspring size at the end of breeding. We observed
consistent among-individual variation in all three behaviors. Males with
higher pre-breeding activity under risk were less likely to reproduce.
However, when these males did breed successfully, they achieved higher
offspring survival rates compared to their less active counterparts. This
relationship was mediated by parental care: males with higher pre-breeding
activity under risk spent more time guarding their brood, and increased
brood guarding was associated with higher offspring survival. Female
pre-breeding activity under risk was not associated with parental care or
reproductive success. These results suggest that male, but not female
boldness might be subject to sexual selection. The observed pattern of
bold males siring fewer but larger broods than less bold males could
maintain among-individual variation in male boldness if it results in
equal average fitness (e.g., due to environmental heterogeneity).