Meeting Abstract
Countergradient variation occurs across environmental gradients when environmental and genetic influences on a phenotype oppose each other. An example of this phenomenon is the inherently faster growth rates observed in animals from higher latitudes compared to their low latitude conspecifics. Enhanced growth is hypothesized to be advantageous for ectotherms from cooler climates to compensate for a shorter growing season and depressed metabolism. Sceloporus consobrinus, the prairie lizard, is an excellent system to study the underlying mechanisms of countergradient variation in growth due to its broad latitudinal range. This study compares S. consobrinus from Missouri to those in Arkansas and provides evidence for countergradient variation in embryonic development. Lizards from Missouri hatched out larger and exhibited shorter incubation times than those from Arkansas. At the same stage of development, embryos from Missouri were larger than those from Arkansas and had less residual yolk, but no differences in metabolic enzymatic activity were observed. This study provides additional support that yolk assimilation rates play a major role in countergradient development.
