title: Does heterospecific seminal fluid reduce fecundity in interspecific copulation between seed beetles?
abstract: Reproductive interference through mating between related species can cause fitness reduction and affect population dynamics of the interacting species. In experimental matings between two seed beetles, Callosobruchus chinensis and Callosobruchus maculatus, C. maculatus females, but not C. chinensis females, suffer from significant loss of fecundity when conspecific mating is followed by heterospecific mating. We hypothesized that male traits associated with sexual conflict, which are often harmful to females, pleiotropically affect fitness of heterospecific females through interspecific mating. We examined the effect of ejaculate of C. chinensis males on C. maculatus females as the cause of the fecundity loss in C. maculatus females due to interspecific copulation. We found that frequent interspecific copulation occurred between C. maculatus females and C. chinensis males, but not between C. chinensis females and C. maculatus males, resulting in frequent interspecific ejaculate transfer from C. chinensis males to C. maculatus females. However, injection of the extract from C. chinensis male reproductive organs into C. maculatus females did not significantly affect C. maculatus fecundity compared with saline injection, indicating that the effect of the heterospecific ejaculate transfer on fecundity is negligible. We suggest that other harmful male traits such as genital spines of C. chinensis males are mainly responsible for the fecundity reduction in C. maculatus females that have experienced interspecific mating.
authors.affiliation: Department of Zoology, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo, Kyoto 606-8502, Japan. Electronic address: d.kyogoku@gmail.com.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kyogoku
authors.affiliation: Department of Zoology, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo, Kyoto 606-8502, Japan. Electronic address: sota@terra.zool.kyoto-u.ac.jp.
authors.forename: Teiji
authors.initials: T
authors.lastname: Sota
mesh_terms: D000818:Animals; D001517:Coleoptera / Q000502:physiology*; D003307:Copulation; D005260:Female; D005298:Fertility / Q000502:physiology*; D008297:Male; D012098:Reproduction / Q000502:physiology; D012661:Semen; D012726:Sexual Behavior, Animal; D013045:Species Specificity
keywords: Genital spine; Interspecific copulation; Interspecific mating; Seminal fluid; Sexual conflict; Toxic substance