April 14, 2014
BECAUSE THEY DON'T CHOOSE TO:
Why don't different species have sex more often? (Matt Soniak, 4/07/14, The Week)
Posted by Orrin Judd at April 14, 2014 4:08 AMDesert woodrats and Bryant's woodrats are closely related. So close, in fact, that the two species can interbreed and produce healthy hybrid offspring. What has scientists puzzled is why they don't do it more often.Both species are members of the genus Neotoma, collectively known as the packrats. They diverged, probably because of geographic isolation, some 1.6 million years ago. Today, the two species are neighbors again in the American West, and despite their genetic distinctions, they can and do mate where their territories butt against each other and produce hybrid rats.In these hybrid zones where the two species overlap, around 13 percent of the population have genes that suggest interbreeding. Why, biologist Quinn Shurtliff, wondered, weren't there more?