After observing hundreds of failed attempts at inter-species lizard love in his laboratory, Jonathan Richardson, a U.S. Geological Survey researcher, realized it may be the size of the skinks that keeps different species from interbreeding.
To successfully mate, the male skink must corkscrew his body around the female and align their genitals. If the alignment is off, so is the courtship.
Different species of Plestidon skink are native to the same parts of Western North America, but are different sizes. So when the different species try to mate, the important parts don't line up.
"As size diverges, the corkscrew fails," Richmond said in a press release. "In this case, it just happens that this is about the only thing necessary to get the ball rolling for speciation."
To test the effect of size on skink mating, Richardson developed a computer simulation of skinks in the throes of reptile romance.
His model backed up his observations that different size skinks could rarely achieve the genital alignment necessary for successful mating.
Since the skinks often occupy the same habitats in the wild, size may be the deciding factor in keeping the different species of skinks in P. skiltonianus group separate.
The research was published in American Naturalist."
Analysis by Tim Wall / Discovery News
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