Meeting Abstract

1.6  Saturday, Jan. 4 09:15  Can physiological flexibility mitigate the effects of climate change in desert lizards? Part I: thermoregulation TODD, J.N.; PIRTLE, E.I.; SANDMEIER, F.C.; TRACY, C.R.; TRACY, C.R.*; Univ. of Nevada, Reno; University of Melbourne; Lindenwood University; Cal. State Univ., Fullerton; Univ. of Nevada, Reno crtracy@mac.com

Others have predicted that climate change will cause mass extinctions of lizards because hotter thermal environments will preclude lizards from thermoregulating to optimal body temperatures. Several lizard species are able to adjust their preferred body temperatures in the different thermal conditions of warm and cool activity seasons, and that ability can mitigate adverse effects of climate change. We studied the common chuckwalla (Saromalus ater) to assess its flexibility to change body temperatures in the cool and hot seasons at two study sites: a cooler high-elevation site (Granite Mts, CA) and a hot low-elevation site (Amboy Crater). In a laboratory thermal gradient, chuckwallas selected the same body-temperature range (34-39°C, corresponding to temperatures at which lizards can sprint maximally) regardless of season or site, and that Tb range is that previously observed in 1970. Lizards in the field emerged from their rock shelters in spring when their preferred body temperatures were possible. In the high-elevation site, lizards were active in springtime during only 70% of the hours when preferred body temperatures were possible, and on 98% of activity-season days, while lizards at Amboy (where food was scare due to a drought) were active only 20% of the hours when preferred temperatures were possible, and on only 54% of activity-season days. These results suggest considerable flexibility for chuckwallas to adjust to predicted change in thermal environments due to global climate change.