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Genital shape matters more than size, evolutionary scientists say

By JohnThomas Didymus     Dec 20, 2011 in Science
Bloomington - Biologists have found that shape matters more than size in the evolution of genitals. Scientists say that genital evolution was very important in the emergence of new species, but it acted first on shape and fit and only much later on size.
Live Science reports that scientists at Indiana University came to the conclusion that shape of genitalia matter more than size in the evolution of species after studying data from scarab beetle populations isolated from each other. The scientists observed that genitalia evolved in parallel between sexes of the same population, but between two newly evolving species, genitals diverged faster from each other in shape than in size.
According to researcher Armin Moczek, biology professor at Indiana University, Bloomington: "Parallel evolutionary divergence in male and female genitalia was something scientists long suspected or assumed, but we've had little or no data to support this assumption...But to see that this parallel divergence is so much faster for genital shape than size is a big surprise."
The scientists were surprised to find that population of beetles separated from each other for only 50 years showed very rapid process of genitalia evolution. This led the scientists to the conclusion that speciation was significantly powered by changes in genital shape leading to emergence of populations genetically isolated from each other because of genital mismatch (i.e. differences in shape of genitals meant that individuals of separate populations were unable to mate). The study of scarab beetle also showed the scientists that the process of genitalia evolution was much faster than they had thought.
According to Live Science, the scientists studying the female and male genitals of five different species of the beetle Onthopagus from around the world, found that the most recently isolated groups were three populations in Eastern United States, Western Australia and Eastern Australia. The populations had all been derived from the Mediterranean.They were introduced into the three regions by human beings in the 1970s.
When the scientists examined those parts of the genitals such as the female pygidium, which interact physically during the act of copulation, they found that size and shape evolved in diverging populations in both sexes, but size evolved more slowly.
More about Genitals, Shape, scarab beetle, Size, Evolution
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