Indiscriminate polyandry and male parental effort

Abstract

Extrapair paternity involves cooperation between mated females and extrapair males. On the other hand, mated males exhibit a spectrum of anti-cuckolding strategies. Hence, extrapair attributes of diverse species and populations reported in the literature are particular solutions of evolutionary games involving gender-specific cuckolding/anti-cuckolding strategies. Here we use game theoretical methods to study the effect of male paternal effort conserving strategies in situations where females seek extrapair fertilizations (EPF) for reasons of genetic compatibility and/or in pursuit of genetic diversity for their offspring. In such cases, females cannot make a pre-copulatory selection of the optimal genetic partners, and therefore combine promiscuous copulation with the use of in copula and/or post-copulatory selection mechanisms to optimize the genetic endowment of their offspring— indiscriminate polyandry. Our results indicate that, when indiscriminate polygamy is constrained by the availability of extrapair male partners, there are three possible (parameter regime wise) evolutionary stable strategy solutions. (1) All females seek EPF, while all males restrict parental care. (2) All females seek EPF, while all males are unconditionally parental. (3) Females use a combination strategy where pursuit of EPF is mixed—on either a population, or an individual level—with genetic monogamy, while all males use a conditional paternal care strategy, which involves adjusting their parental efforts according to their certainty of paternity.