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The Maternal Instincts of Side-Blotched Lizards

Posted By G Living Staff Monkies On March 25, 2008 @ 4:04 pm In G Living,Nature / Non Human Stories | No Comments

Even those of us without kids of our own can comprehend the maternal instinct women have to protect their children. (If you can’t comprehend this, you might be a threat to society and should submit yourself for testing.) Mothers, consciously or not, have a predisposition toward arming their offspring with the necessary skills to survive in this crazy world of ours. Research has shown that animals have this instinct as well.

But the results of a recent study show that female side-blotched lizards have a particularly fascinating way of “dressing their children for success” – by using hormones to selectively trigger a desired physical appearance in their offspring.

The most abundant lizard species in the western U.S., the side-blotched (Uta stansburiana) often falls victim to predators like the coachwhip snake. The way lizards of all variety protect themselves is by camouflaging themselves in surroundings that match the patterns on their backs.

A Live Science article tells us that yellow-throated males, which are prone to hiding in grass, “have a pattern of bars stretching from side to side that breaks up the outline of their bodies”, thus aiding their ability to camouflage. Orange-throated males, on the other hand, are a more aggressive variety, one that often commandeers the habitats of other lizards. Since they’re less likely to be found hiding in grass, they “employ lengthwise stripes down their backs to help them escape from predators, as stripes on fast-moving prey helps disrupt the outlines of their bodies, making them harder to catch.”

But do the patterns on their backs reflect their behavior by coincidence? Or does their pattern dictate their behavior? Neither, says the article. “The genes that control behavior and back patterns in side-blotched lizards are not linked, so a lizard could end up with a mismatch that would leave it highly vulnerable to predators.”

But taking this one step further, researchers have learned that the female side-blotched lizard has the power to vary the amount of the hormone estradiol they provide their eggs, which has a direct result on the back pattern of their offspring.

“This is the first example in which exposure to the mother’s hormones changes such a fundamental aspect of appearance,” behavioral ecologist Lesley Lancaster is quoted as saying. “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.”

The ecologist discovered this amazing ability by testing side-blotched lizard eggs found in the wild. What she discovered was that a high variance of estradiol concentrations occurred naturally in the eggs’ yolks. She then treated the eggs with alternate hormones to see the effect they had on the influence of the lizards’ physical patterns. Her study included experiments in breeding 71 males with three females apiece and examining the eggs for hormone levels and then observing the patterns that emerged among the 1,206 offspring.

She learned that the females altered the amount of estradiol they provided to the eggs based on the colors of their mates’ throats and those of other nearby males. The study led her to theorize that “the females are responding to cues that predict something about the future environment.”

Once the lizards were released into the wild, “she found motherly tweaking of back patterns clearly helped their progeny fare better, with the highest survival rates seen in yellow-throated lizards with barred backs and orange-throated males with striped backs.” She speculates that other species may have similar maternal influence over their offspring’s appearance.

Do human females have this amazing ability as well? My guess is no. But one day science may tell us.

(via Live Science)


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