Compensating for a bad start:: Catch-up growth in juvenile lizards (Amphibolurus muricatus, Agamidae)

In most natural environments, food availability varies unpredictably through space and time, and growth rates of individual organisms respond accordingly. However, growth rates are not necessarily a simple function of current nutritional conditions: growth rates can be affected by earlier nutritional experience as well as current circumstances. Thus, even a brief period of dietary restriction early in life might influence growth rates later on: either reducing them (if early experience sets subsequent rates, as in the "silver spoon" effect) or increasing them (if underfed individuals can compensate by growing more rapidly to cancel out the early decrement). Alternatively, later growth may be unaffected by earlier rates of growth. We experimentally manipulated food supply (and thus, growth rates) of hatchling lizards (Amphibolurus muricatus) for 1 month post-hatching, then maintained both high-food and low-food animals under identical nutritional conditions in outdoor enclosures for another 6 months. Low food abundance early in life significantly reduced juvenile growth, but these previously underfed animals exploited the subsequent (common garden) conditions to grow much faster than their larger (initially better-fed) siblings. Thus, the two groups were indistinguishable in body size at 6 months of age. Intriguingly, the compensatory growth occurred in winter, a period that is generally unsuitable for rapid growth in ectotherms.