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GENITAL LOCK‐AND‐KEY AS A SELECTIVE AGENT AGAINST HYBRIDIZATION
Author(s) -
Sota Teiji,
Kubota Kohei
Publication year - 1998
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/j.1558-5646.1998.tb02033.x
Subject(s) - biology , interspecific competition , intraspecific competition , mating , hatching , zoology , sex organ , offspring , reproductive isolation , ecology , sexual selection , demography , botany , genetics , pregnancy , population , sociology
We demonstrate experimentally that differences in genital characters impose a direct cost of interspecific copulation on two closely related carabid species, Carabus (Ohomopterus) maiyasanus and C. ( O .) iwawakianus , that share a narrow hybrid zone. Males of both species attempted copulation indiscriminately between conspecific and heterospecific females. Females experiencing heterospecific mating often suffered mortality due to rupture of their vaginal membranes. Those without fatal injury laid eggs which developed into F 1 adults, but the fertilization rate was much lower than for intraspecific pairs. Males of C. maiyasanus , but not C. iwawakianus , often had broken genital parts (copulatory pieces) following interspecific copulations, which may prevent normal copulation in subsequent matings. Because of female mortality and low fertilization rate, the estimated fitness cost of interspecific mating was very large in terms of the reduction in the number of offspring (hatching larvae) for both sexes and both species. Thus, genital lock‐and‐key appears to exert significant selection against hybridization in the hybrid zone of these carabid beetles.