Evidence against the Spermatophore as Paternal Investment in Checkerspot Butterflies (Euphydryas: Nymphalidae)

Abstract

Two butterfly species, Euphydryas editha and E. chalcedona, were examined in a laboratory experiment to test whether the reproductive output of a mating is affected by the weight of the male-donated spermatophore. Ejaculate weight was determined by weighing males before and after mating. Reproductive output was measured as the number of eggs laid and the percentage that hatched. Spermatophore weight did not influence reproductive output in either species. We found no evidence that the spermatophore constitutes a significant paternal investment in these species.