SocialBiol - The biology of friendship: How non-sexual social associations shape sexual selection and phenotypic evolution

Sexual selection explains the evolution of many traits that do not enhance survival, but instead confer advantages in reproduction. However, traditional research focusing on mate choice and in competition for mates is insufficient to understand how sexual selection operates in social animals, which also experience various non-sexual interactions. A good understanding of sexual selection in those species needs to consider how phenotypic traits affect reproductive as well as non-reproductive social associations. We use a highly gregarious avian species, the common waxbill, to study how phenotypic traits affect social associations during the non-breeding season, and how those associations in turn influence pair formation towards the breeding season.

We use network analyses of flocks in semi-natural conditions, monitored year-round via an automatic tracking system, to test for social effects of natural and experimentally-created variation in phenotypes (e.g. ornamentation, behavioural differences). The questions we address include, among others, whether the same or different phenotypic traits influence sexual and non-sexual social preferences, and which phenotypic correlates of mate choice are mate preferences or carry-over effects from earlier non-sexual associations. This will be perhaps the most detailed case study of the interplay between non-sexual and sexual social interactions, and should enlighten our understanding of animal sociality, and the evolution of phenotypes that mediate it.