Meeting Abstract

73.5  Sunday, Jan. 6  Do long term changes in environmental temprature affect thermal tolerance in lizards? MCMILLAN, D.M*; IRSCHICK, D.J.; Univ. of Massachusetts, Amherst; Univ. of Massachusetts, Amherst

In recent years, ecologists have emphasized studies on the effects of global climate change on naturally occurring animal populations. However, climatic changes are often subtle, and detecting differences often require large, long term data sets. One of the predicted possible outcomes of global climate change is that the number of days in which there are extreme hot or cold temperatures can increase even if the overall mean temperature does not. Thermal tolerance is the ability of an organism to withstand acute periods of high temperature; one common measure of thermal tolerance is Critical Thermal Maximum (CTmax), defined as the temperature above which an animal loses voluntary muscle control. In this study we used CTmax to discern whether a shift in the thermal profile of a local habitat over time leads to a change in the way an animal is able to withstand periods of extreme temperature. During the summer of 2007, we collected male fence lizards, Sceloporous occidentalis, in the San Gabriel Mountains of southern California. We measured the CTmax of these individuals and compared them to lizards previously collected at these study sites. Here we discuss the implications of changes in thermal tolerance for the survivorship of animals in the face of changing thermal regimes. In addition, we explore possible mechanisms through which increased thermal tolerance may be achieved in the short term, namely through the expression of heat shock proteins.