If you've ever had a meal that changed your life, maybe you understand what it's like to be a newborn lizard. If you're a Zootoca vivipara lizard, whether or not you get an easy first meal may change the course of your life, according to a pair of scientists in France and Spain.
The study, published in Current Biology, shows that small, even fleeting events in an animal's life can dramatically alter an animal's development, even if it has the same genes as its brethren.
At a national park in southern France, the researchers captured 120 pregnant Zootoca vivipara lizards, insect-eaters that birth their young live rather than laying eggs. Two days after the young were born, the scientists fed a single meal to 280 offspring and did not feed another group of 289 baby lizards. The scientists, observing the baby lizards, found that the ones denied food tried to make attempts to capture prey (all in vain in the lab environment, of course). They were released back into the wild on their third day of life, in the same area their mothers were caught.
Within 10 days, the two groups' fates diverged. Those that had received a meal were extremely unlikely to leave the spot where they were released, while the ones that had gone hungry were more willing to go roaming.
When the researchers went to recapture the lizards (which had been individually marked by toe clipping), they found that the unfed lizards were much easier to recapture than the ones that had received a meal. It was unclear why; the researchers said it could have to do with "a greater ability to escape, lower activity, or reduced risk-taking behavior."
Two years after their release, the litters produced by the unfed females were actually larger than those birthed by lizards who'd received a hearty first meal – an average of 4.3 babies as opposed to 2.9. This counterintuitive finding "contradicted our expectation," the authors wrote, calling it an "overcompensatory phenotypic response."
The research shows that even fleeting events in an animal's early life can dramatically change its development -- a finding that has significant implications for the study of evolutionary biology, the researchers said.