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Thursday, June 14, 2007

Designer Lizards

Researchers have found that female side-blotched lizards are able to induce different color patterns in their offspring in response to social cues, "dressing" their progeny in patterns they will wear for the rest of their lives. The mother's influence gives her progeny the patterns most likely to ensure success under the conditions they will encounter as adults.


Spider-Man & The Lizard © Marvel Comics

The lizards' main predator, the coachwhip snake, is a highly efficient hunter, and the lizards need just the right combination of traits to avoid being eaten. Sneaky yellow-throated males like to hide in the grass and need a barred pattern that breaks up the outline of their body so it blends in with the background. Aggressive orange males spend a lot of time in the open and need stripes to help them escape from predators (the optical effect of stripes on fast-moving prey makes them hard to catch).

The researchers reported that female side-blotched lizards give an extra dose of the hormone estradiol to their eggs in certain social circumstances. The extra hormone affects the back patterns of lizards that hatch from those eggs, creating either lengthwise stripes down their backs or bars stretching from side to side. Whether they get stripes or bars depends on the genes for other traits.

"This is the first example in which exposure to the mother's hormones changes such a fundamental aspect of appearance. Even more exciting is that the mother has different patterns at her disposal, so she can ensure a good match between back patterns and other traits that her offspring possess," said Lesley Lancaster. link