Evolutionary Adaptation Breeds Gender-identification Confusion - Science News
PORTLAND, Ore. — The recent evolution of camouflage among lizards in the powdery dunes of New Mexico’s White Sands National Monument can lead to some misunderstandings when some males choose to make love, not war.
Since the dunes developed a few thousand years ago, a light-colored form of the normally dark-shaded eastern fence lizard (Sceloporus undulates) has arisen that blends in with the landscape.
The change in hue can produce confusion over sex-recognition signals, Jeanne Robertson of the University of Idaho in Moscow reported June 27 at the Evolution 2010 meeting. At least it did when she and an associate arranged encounters between pale White Sands lizards and their darker cousins from the area surrounding the dunes.
Whenever she and University of Idaho colleague Erica Bree Rosenblum put a pale male lizard and a male from dark soil together, the dark lizard gets ready to fight, positioning himself sideways and showing off his bulk and his blue belly. He does some menacing push-ups and prepares for the head-butting and tail-whipping common in aggressive lizard encounters.
Aside from causing amusing problems with courtship, there’s a deeper message here, says Jonathan Losos of Harvard University. Sex-identification miscues can make it less likely for members of different populations to mate if they happen to meet. “As a result, adaptation to different environments may have the incidental effect of leading to reproductive isolation, and hence the origin of distinct species,” he says.