Extra-Pair Paternity and Sexual Selection

Abstract

Parentage analyses can reveal hidden reproductive interactions between individuals that are not social partners. Extra-pair mating is a special case of promiscuity where social pair bonds exist and persist despite copulations with multiple partners by one or both pair members. The relevance of extra-pair interactions in reshaping social mating systems varies among species. In some species or populations, extra-pair matings are no more than exceptional events (e.g., Dearborn et al. 2001; Egger et al. 2006), whereas in others extra-pair paternity (EPP) is a phenomenon that cannot be ignored when describing mating patterns because of a substantial discrepancy between the observable apparent mating system and the actually realized mating system (e.g., Double and Cockburn 2003; Sefc et al. 2008). Extrapair copulations (EPCs) are of special interest in socially monogamous species where promiscuity is otherwise absent. Pair bonding and social monogamy are relatively rare – except in birds (Lack 1968, p. 148) – yet occur in a wide range of animal taxa (e.g., Caldwell 1997; Kvarnemo et al. 2000; Baeza 2008; Steinauer 2009). However, social monogamy frequently goes hand in hand with multiple mating (e.g., Griffith et al. 2002; Chapple 2003; Lodé and Lesbarrères 2004; Cohas and Allainé 2009).