Genetic variation in nuclear and mitochondrial markers supports a large sex difference in lifetime reproductive skew in a lekking species

Sex differences in skews of vertebrate lifetime reproductive success are difficult to measure directly. Evolutionary histories of differential skew should be detectable in the genome. For example, male-biased skew should reduce variation in the biparentally inherited genome relative to the maternally inherited genome. We tested this approach in lek-breeding ruff (Class Aves, Philomachus pugnax) by comparing genetic variation of nuclear microsatellites ((n); biparental) versus mitochondrial D-loop sequences ((m); maternal), and conversion to comparable nuclear (N-e) and female (N-ef) effective population size using published ranges of mutation rates for each marker (). We provide a Bayesian method to calculate N-e ((n)=4N(en)) and N-ef ((m)=2N(efm)) using 95% credible intervals (CI) of (n) and (m) as informative priors, and accounting for uncertainty in . In 96 male ruffs from one population, N-e was 97% (79-100%) lower than expected under random mating in an ideal population, where N-e:N-ef=2. This substantially lower autosomal variation represents the first genomic support of strong male reproductive skew in a lekking species.