The physiology of all ectothermic organisms is tied integrally to the balance between heat and water availability. Consequently, temperature and rainfall are primary ecological drivers for biodiversity. In two different studies, we examined how variation in rainfall and temperature regimes could interact with the growth and reproduction of two ectotherms. These are both novel studies because we directly measured growth and reproduction associated with historical temperature and rainfall data and then used fuzzy regression to predict how future changes in these regimes might influence population stability. At first glance, we expected populations to thrive under wetter and warmer conditions. In fact, its the timing of the change that is critical, even more so than the magnitude of extremes. Raised temperatures in winter likely burn resources., wetter periods during some seasons were more vital/damaging than others. Both of these manuscripts were discussed in a high panel on climate change at the United Nations.
Box Turtles and Climate Change
We lined growth rings in turtle shells up with the years in which that growth occurred. We measured the amount of growth and recorded the seasonal rainfall and thermal regimes during that year. This allowed us to create a regression in which seasonal weather predicted growth. Then, using that regression model, we used fuzzy sets as predictors to infer what the worst and best case scenarios for growth were based on the future projections from climate change. A later study by others used radio telemetry validated this study with box turtles growing as we predicted under the temperature regimes that ultimately took place. The only attempt at this kind of study was done with Arctic Charr.
McCallum, M.L., J.L. McCallum, S.E. Trauth. 2009. Predicted climate change may spark box turtle declines. Amphibia-Reptilia 30:259-264.
Climate Change and Blanchard's Cricket Frog
Blanchard's Cricket Frog is a small frog on which I have conducted much research. This study took a similar approach to the box turtle paper posted adjacently. The main differences was that most of the time cricket frogs only live a single year. So, any measure of snout-vent length or weight is a stand-alone point in time directly related to the environmental cues experienced by the animal in the previous period since emerging from a pond. In this case, we had full reproductive data and could directly model the impacts of changed temperature regimes on growth and then reproduction.
McCallum, M.L., 2010. Future Climate Change Spells Catastrophe for Blanchard’s Cricket Frog, Acris blanchardi (Amphibia, Anura, Hylidae). Acta Herpetologica 5(1):119-130.