Data for: Paternity sharing in insects with female competition for nuptial gifts

Male parental investment is expected to be associated with high confidence
of paternity. Studies of species with exclusive male parental care have
provided support for this hypothesis because mating typically co-occurs
with each oviposition, allowing control over paternity and the allocation
of care. However, in systems where males invest by feeding mates
(typically arthropods) mating (and thus the investment) is separated from
egg-laying, resulting in less control over insemination (as male
ejaculates compete with rival sperm stored by females) and a greater risk
of investing in unrelated offspring (cuckoldry). As strong selection on
males to increase paternity would compromise the fitness of all a female’s
other mates that make costly nutrient contributions, paternity sharing
(males not excluded from siring offspring) is an expected outcome of sperm
competition. Using wild-caught females in an orthopteran and a dipteran
species, in which sexually selected, ornamented females compete for male
nuptial food gifts needed for successful reproduction, we examined
paternity patterns and compared them to findings in other insects. We used
microsatellite analysis of offspring (lifetime reproduction in the
orthopteran) and stored sperm from wild-caught females in both study
species, and as predicted there was evidence of shared paternity as few
males failed to sire offspring. Further support for paternity-sharing is
the lack of last-male sperm precedence in our study species. Although
paternity was not equal among sires, our estimates of paternity bias were
similar to other insects with valuable nuptial gifts and contrasted with
the finding that males are frequently excluded from siring offspring in
species where males supply little more than sperm. This suggests paternity
bias may be reduced in nuptial-gift systems and may help facilitate the
evolution of these paternal investments.