Males,but not females,contribute to sexual isolation between two sympatric species of <Emphasis Type="Italic">Gambusia</Emphasis> |
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Authors: | Celeste M Espinedo Caitlin R Gabor Andrea S Aspbury |
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Institution: | (1) Department of Biology, Texas State University-San Marcos, San Marcos, TX 78666, USA;(2) Present address: Department of Earth and Environmental Sciences, University of New Orleans, New Orleans, LA 70148, USA; |
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Abstract: | Reproductive isolation restricts genetic exchange between species. Various pre- and post-mating barriers, such as behavior,
physiology and gametic incompatibility, have been shown to evolve in sympatry. In certain scenarios, isolation can be asymmetrical,
where species differentially prefer conspecifics. We examined sexual isolation via conspecific mate preference between Gambusia affinis and G. geiseri in both sexes. To investigate male contribution to sexual isolation, we compared the number of mating attempts (gonopodial
thrusts) directed at either a conspecific or a heterospecific female, in both species. We also examined sperm priming and
expenditure in males in the presence of conspecific or heterospecific females. We then measured female preference for either
a conspecific or heterospecific male, in both species. We found that males of both species preferred to mate with conspecific
females, but showed no difference in sperm production or expenditure between conspecific and heterospecific females. Females
of both species did not prefer conspecific over heterospecific males. Our results suggest that sexual isolation might be mediated
by male mate choice in this system and not female choice, suggesting that there is asymmetrical reproductive isolation between
the sexes in G. affinis and G. geiseri, but symmetrical species isolation. |
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