Extra-pair copulation and extra-pair paternity in birds

摘要

Dunn & Lifjeld (1994) indicate that in our original analysis (Birkhead & Moller 1992) of the relationship between extra-pair copulation and extra-pair paternity in birds some of the data we used were inappropriate. Specifically, they state that data for polygynandrous dunnocks, Prunella modularis, should not have been included in the analysis, and that the data for the splendid fairy-wren, Malurus splendens, were incorrect. In the first chapter of Sperm Competition in Birds (Birkhead & Moller 1992) we made it clear (page 12) that we were interested in female copulations with multiple partners, and state that 'extra-pair copulations can occur in all mating systems'. We also make it explicit (page 11) that our definition of extra-pair copulation differed from that of Westneat et al. (1990) to which Dunn & Lifjeld refer. We used a broad definition of extra-pair copulation because sperm competition is about the evolutionary consequences of multiple mating by females in terms of paternity, regardless of social bonds. We therefore feel entirely justified in including data from poly-androus and polygynandrous dunnocks in our original analysis.