Showing posts with label ectotherms. Show all posts
Showing posts with label ectotherms. Show all posts

Saturday, March 31, 2012

The Side-Blotched Lizard & A Warming Climate

A side-blotched lizard, Pima Co., AZ, JCM
Side-blotched lizards of the genus Uta are perhaps the most abundant and most frequently seen lizards in western North American deserts. Males are usually larger than females and have brightly colored throats that are used to signal other lizards. They mature rapidly and reproduce at young age. Many fall prey to a variety of birds, mammals, and other reptile, thus in some populations few live longer than a year. Mature females regularly lay two clutches (and in some years possibly three), yearlings frequently lay only one clutch unless environmental conditions are especially favorable.

Clark & Zani (2012) used the side-blotched lizard to examine the impact of climate change, hypothsizing that temperate ectotherms, especially those at higher latitudes, would benefit from climate warming. Most previous studies on the effects of climate change use a model of uniform annual change, which assumes that temperature increases are symmetric on diurnal or seasonal time scales. In this study, Clark & Zani simulated observed trends in the asymmetric alteration of diurnal temperature range by increasing night-time temperatures experienced by female lizards during their ovarian cycle as well as by the resulting eggs during their incubation. They found that higher night-time temperatures during the ovarian cycle increased the probability of reproductive success and decreased the duration of the reproductive cycle, but did not affect embryo stage or size at oviposition, clutch size, egg mass or relative clutch mass. However, higher incubation temperatures increased hatchling size and decreased incubation period but had no effect on incubation success. Subsequent hatchlings were more likely to survive winter if they hatched earlier, but the sample size of hatchlings was relatively small. Their results suggest higher night-time temperatures affect the rates of processes and that certain aspects of life history are less directly temperature dependent. Thus climate warming is likely to increase the rate of development as well as advance reproductive phenology, and the authors predict that warmer nights during the breeding season will increase reproductive output as well as subsequent survival in many temperate ectotherms, both of which should have positive fitness effects.

Clarke DN, and Zani PA. 2012. Effects of night-time warming on temperate ectotherm reproduction: potential fitness benefits of climate change for side-blotched lizards, Journal of Experimental Biology 215:1117-1127. doi:10.1242/jeb065359