Nuptial gifts and sexual selection in photinus fireflies

The phenomenon of nuptial gift transfer during mating occursacross a remarkably wide range of taxa, and such male donationsare likely to influence both pre-copulatory and post-copulatorysexual selection. This paper reviews what is known about nuptialgifts in Photinus fireflies (Coleoptera: Lampyridae), and discussesthe adaptive significance of spermatophores in firefly matingsystems. During copulation Photinus males transfer a spiral,gelatinous spermatophore to the female: sperm are released intothe female's spermatheca for storage, while the remainder ofthe spermatophore disintegrates within a specialized gland.Radiolabelling studies indicate that male-derived protein isused to help provision the female's developing oocytes, andmultiply-mated females show increased fecundity. As most Photinusadults do not feed, these studies suggest that females shouldcontinue to forage for matings to supplement their diminishinglarval reserves, even after they have gained sufficient spermto fertilize their eggs. Male spermatophore mass declines acrosssequential matings, and smaller spermatophores are associatedwith lower paternity success in situations where males competefor fertilizations. Declining spermatophore size across sequentialmatings may thus lead to diminishing reproductive returns forfirefly males. Taken together, these results suggest that seasonalchanges in nuptial gift availability may contribute to reversalsof traditional courtship roles, with male choice and female-femalecompetition occurring as spermatophore availability declines.