Passerine extra-pair mating dynamics: A model-based comparison of four species.

Brommer, Jon E. and Alho, Jussi S. and Biard, Clotilde and Chapman, Joanne R. and Charmantier, Anne and Dreiss, Amelie and Hartley, Ian R. and Hjernquist, Marten B. and Kempenaers, Bart and Komdeur, Jan and Laaksonen, Toni and Lehtonen, Paula K. and Lubjuhn, Thomas and Patrick, Samantha C. and Rosivall, Balazs and Tinbergen, Joost M. and van der Velde, Marco and van Oers, Kees and Wilk, Tomasz and Winkel, Wolfgang (2010) Passerine extra-pair mating dynamics: A model-based comparison of four species. The American Naturalist, 176 (2). pp. 178-187. ISSN 1537-5323

Abstract

In many socially monogamous animals, females engage in extrapair copulation (EPC), causing some broods to contain both within-pair and extrapair young (EPY). The proportion of all young that are EPY varies across populations and species. Because an EPC that does not result in EPY leaves no forensic trace, this variation in the proportion of EPY reflects both variation in the tendency to engage in EPC and variation in the extrapair fertilization (EPF) process across populations and species. We analyzed data on the distribution of EPY in broods of four passerines (blue tit, great tit, collared flycatcher, and pied flycatcher), with 18,564 genotyped nestlings from 2,346 broods in two to nine populations per species. Our Bayesian modeling approach estimated the underlying probability function of EPC (assumed to be a Poisson function) and conditional binomial EPF probability.We used an information theoretical approach to show that the expected distribution of EPC per female varies across populations but that EPF probabilities vary on the above-species level (tits vs. flycatchers). Hence, for these four passerines, our model suggests that the probability of an EPC mainly is determined by ecological (population-specific) conditions, whereas EPF probabilities reflect processes that are fixed above the species level.