SREL Reprint #1169




Savannah River Ecology Laboratory, Aiken

Ethological Isolation, Sexual Behavior and Pheromones in the Fasciatus Species Group of the Lizard Genus Eumeces

William E. Cooper, Jr. and Laurie J. Vitt



Ethological isolation was found among North American members of the fasciatus species group of Eumeces.  Ethological isolation was investigated by staging a series of interspecific and intraspecific heterosexual encounters.  No male E. laticeps or E. fasciatus courted heterospecific females.  In both species, males courted and copulated with conspecific females in a significantly higher frequency of trials than with heterospecific females.  However, male E. inexpectatus courted females of all three species, courting conspecific females and female E. laticeps at similar frequencies, but female E. fasciatus at a significantly lower frequency.  No females of any of three species were sexually receptive to heterospecific males, but forced copulation occur din two of nine courtships of female E. fasciatus by male E. inexpectatus.  Thus, ethological isolation in the fasciatus group appears to be complete with the possible exception of occasional forced copulation between male E. inexpecatus and female E. fasciatus.  Preliminary evidence on the role of chemical stimuli in maintaining ethological isolation was obtained from experiments involving interspecific transfers of female odors.  Male E. inexpectatus courted female E. fasicatus labeled with the odor of female E. inexpecatus in a significantly greater proportion of trials than they courted such females lacking the conspecific female odor.  In a similar experiment, male E. fasicatus did not court female E. inexpectatus even if the females bore odors of female fasciatus.


SREL Reprint #1169

Cooper, W.E., Jr. and L.J. Vitt. 1987. Ethological isolation, sexual behavior and pheromones in the Fasciatus species group of the lizard genus Eumeces. Ethology 75:328-336.

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