Genetic dissimilarity predicts paternity in the smooth newt (Lissotriton vulgaris)

Abstract

Under sperm competition, paternity is apportioned by polyandrous females according to the order of matings and the genetic quality of the inseminating males. In order to distinguish between these two effects, we sequentially paired 12 female smooth newts (Lissotriton vulgaris) with each of two males and, where possible, repeated the same procedure in reverse order of the identical males after assumed sperm depletion. For a total of 578 offspring, amplified fragment length polymorphisms genetic markers revealed multiple paternities in all matings, without significant first- or second-male sperm precedence. The paternity share of individual males was transitive across the two trials with male order switch, and successful males had a significantly higher genetic dissimilarity to the female than expected by chance. We argue that patterns of paternity in natural newt populations are determined through a combination of good genes and relatedness.

Figure 1

Difference in relatedness coefficient (SM_diff) for those male smooth newts (L. vulgaris), which sired more offspring than the competitor when inseminating one female. The dotted line indicates the expected average when relatedness plays no role in determining paternity. Circles represent trial 1 and squares represent trial 2 (see text). Colour indicates mating order (white, first male; grey, second male). Symbol size scales linearly with total number of offspring.