Ethological Isolation, Sexual Behavior and Pheromones in theFasciatusSpecies Group of the Lizard GenusEumeces

摘要

AbstractEthological isolation was found among North American members of thefasciatusspecies group ofEumeces.Ethological isolation was investigated by staging a series of interspecific and intraspecific heterosexual encounters. No maleE. laticepsorE. fasciatuscourted heterospecific females. In both species, males courted and copulated with conspecific females in a significantly higher frequency of trials than with heterospecific females. However, maleE. inexpectatuscourted females of all three species, courting conspecific females and femaleE. laticepsat similar frequencies, but femaleE. fasciatusat a significantly lower frequency. No females of any of the three species were sexually receptive to heterospecific males, but forced copulation occurred in two of nine courtships of femaleE. fasciatusby maleE. inexpectatus.Thus, ethological isolation in thefasciatusgroup appears to be complete with the possible exception of occasional forced copulation between maleE. inexpectatusand femaleE. fasciatus.Preliminary evidence on the role of chemical stimuli in maintaining ethological isolation was obtained from experiments involving interspecific transfers of female odors. MaleE. inexpectatuscourted femaleE. fasciatuslabelled with the odor of femaleE. inexpectatusin a significantly greater proportion of trials than they courted such females lacking the conspecific female odor. In a similar experiment, maleE. fasciatusdid not court femaleE. inexpectatuseven if the females bore odors of femalefasciatus.