Social drivers of extra-pair paternity

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Variation in the expression of extra-pair paternity (EPP) among individuals of the same population could result from stochastic demography or from individual differences in mating strategies. Although the adaptive value of EPP has been widely studied, little is yet known about the characteristics of the social environment that drive the observed patterns of EPP. I propose to investigate the characteristics of the social environment in which individuals are embedded that influence the levels of EPP in a population. I hypothesise that social attributes such as degree of connection among individuals and the strength of social bonds can explain the variation in the patterns of extra-pair copulations (EPCs) and EPP, and that the sociality of individuals is influenced by genetic mechanisms. I propose to use two selection lines of domestic zebra finches (with low and high EPP levels), along with a recently wild-derived line (very low EPP) to characterize and compare the social behaviour and patterns of EPP, in replicated experiments, over the course of three years. First, I will use state-of the-art tracking technologies in combination with social network analyses to quantify the directionality of the social interactions and the social structure of the groups at three levels: individual (e.g. degree), dyad (e.g. strength) and group (e.g. phenotypic group composition); and I will use parentage analysis to determine the genetic mating patterns. Then, I will use linear mixed models to determine the relationship between social attributes and levels of EPP and EPCs and animal models to quantify the heritability of social traits. By understanding the interplay between the social environment and the mating systems I will contribute to the explanation of the proximate mechanisms that drive variation in EPP within populations, and ultimately to understand the evolution and maintenance of mating systems.