Linking infidelity with behaviour in social networks
Infidelity is common among many taxa with prevailing social monogamy, but we still do not know what shapes variation in, and drives the evolution of, extra-pair behaviour. Males are expected to reap fitness benefits from siring extra-pair offspring, because extra-pair fathers do not expend resources on costly parental care. This is, however, not the case for females who raise the resulting extra-pair young, posing the question of why females take part in extra-pair matings. The indirect benefits hypothesis explains female infidelity, where females benefit indirectly from better, or more compatible genes for their offspring. However, this hypothesis is not well supported empirically, evidenced by two contradictory meta-analyses on the topic, and ongoing discussion in the field. Specifically, only one long-term study that quantified life-time reproductive success supports the indirect fitness benefits hypothesis. Contradicting this result, extra-pair males have not been found to be superior, or more compatible, than a female’s within-pair male. Females were found to incur no indirect benefits, and even fitness costs by mating outside of their pair bond, suggesting that that this hypothesis does not satisfactorily explain why females cheat. Recently suggested novel, testable hypotheses provide a fresh perspective. These hypotheses explain female infidelity with intra- and intersexual antagonistic pleiotropy, and remain largely untested. This project aims to empirically test these hypotheses by using the powerful combination of long-term data from a wild population, state-of-the-art social network analysis and manipulative experiments on captive birds. This project will reap the benefits from long-term data in the wild, where precise fitness data and a genetic pedigree allow fitness costs and benefits to be measured, and quantitative genetic analyses. Given the long-standing conundrum of female extra-pair behaviour, this project has the potential forward this field significantly.
For more information, contact julia.schroeder[a]imperial.ac.uk