Meeting Abstract

2.4  Sunday, Jan. 4  Influences of short- and long-term climate fluctuations on ectotherm life histories revealed by biophysical modeling of lizards ZANI, P.A.*; ROLLYSON, M.E.; Lafayette College; Lafayette College zanip@lafayette.edu

Global climate change continues to impact the seasonal timing of events such as the onset of favorable and unfavorable growing seasons. By examining past changes in climate one may understand how future changes will impact organisms. We created a biophysical model that predicts spring emergence, onset of reproduction (oviposition), and winter retreat for an ectotherm, the side-blotched lizard (Uta stansburiana), using temperature and day-length data as well as assumptions about activity and preferred body temperatures. Following verification of the model using multi-year life-history data from a lizard population in eastern Oregon, we used meteorological data for the past 70 years to test the hypothesis that spring emergence and oviposition have been advanced (earlier onset) and that winter retreat has been delayed due to changing climate. Results indicate that for this Pacific Northwest population spring emergence is actually later in recent years, oviposition is unchanged, and the onset of winter is progressively earlier. Further investigation revealed a significant correlation between short-term climate fluctuations (El Nino-Southern Oscillation [ENSO]) and oviposition (but not emergence or retreat) such that warm, dry winters (positive ENSO) in the Northwest result in the early onset of oviposition. Interestingly, long-term climate fluctuations (Pacific Decadal Oscillation [PDO]) are correlated with retreat (but not emergence or oviposition) such that warm periods (positive PDO) result in the earlier onset of winter in this population. Thus, in order to understand the effects of climate change on the life histories of organisms it may be necessary to take into account the influences of regional climate as well as short- and long-term climate fluctuations.