Data from: High levels of polyandry, but limited evidence for multiple paternity, in wild populations of the western rock lobster (Panulirus cygnus)

Polyandry, where multiple mating by females results in the temporal and
spatial overlap of ejaculates from two or more males, is taxonomically
widespread and occurs in varying frequencies within and among species. In
decapods (crabs, lobsters, crayfish and prawns), rates of polyandry are
likely to be variable, but the extent to which patterns of multiple
paternity reflect multiple mating, and thus are shaped by post-mating
processes that bias fertilization towards one or a subset of mated males,
is unclear. Here, we use microsatellite markers to examine the frequency
of multiple mating (presence of spermatophores from two or more males) and
patterns of paternity in wild populations of western rock lobster
(Panulirus cygnus). Our data confirm that >45% of females had
attached spermatophores arising from at least two males (i.e. confirming
polyandry), but we found very limited evidence for multiple paternity;
among 24 clutches sampled in this study, only two arose from
fertilisations by two or more males. Single inferred paternal genotypes
accounted for all remaining progeny genotypes in each clutch, including
several instances when the mother had been shown to mate with two or more
males. These findings highlight the need for further work to understand
whether polyandry is adaptive and to uncover the mechanisms underlying
post-mating paternity biases in this system.