Multiple paternity in a salamander with socially monogamous behaviour.

In the majority of birds and mammals, social monogamy is not congruent with genetic monogamy. No research to date has compared social and genetic monogamy in amphibians. We analysed paternity in clutches of red-backed salamanders (Plethodon cinereus), a species in which social monogamy has been demonstrated in the laboratory, and 28% of individuals in the forest are found in male-female pairs in the noncourtship season. We collected 16 clutches of eggs of P. cinereus in the southern Appalachian Mountains of Virginia and collected tail clippings from attending mothers. We genotyped embryos and adults at five microsatellite loci in order to analyse paternity of clutches. Most clutches (84.6%) had multiple sires, with two to three sires per clutch. In this study, 25% of clutches had males in addition to females attending eggs. None of the mothers of these clutches were genetically monogamous. All attending males sired some of the offspring in the clutch that they attended (between 9% and 50%) but never sired a majority in that clutch. We conclude that, at least in this population, social monogamy in P. cinereus is not concomitant with genetic monogamy.