Meeting Abstract
Climate change may decrease the amount of time environmental temperatures are suitable for ectotherm activity, thus reducing time available for energy acquisition, territorial displays and reproduction. To assess potential impacts of climate change on populations, it is important to study how lizards use their time for activity. Male common chuckwallas (Sauromalus ater) do not use all of the time where temperatures are suitable for activity (outside of rock crevices), suggesting that climate change will have minor effects on their ability to perform such activities. However, sex differences in the use of suitable activity time could result in reduced reproductive output of the population in the face of climate change, so we studied female thermoregulatory behavior for comparison. We measured body temperatures (Tb) of 5 female and 1 male chuckwalla in a semi-natural enclosure every 15 min during summer. To determine how chuckwallas used the thermal environment, we compared Tb to environmental temperatures (Te), measured with copper models that mimic heat exchange of chuckwallas. The proportion of time females were active relative to the time with suitable Te (0.71 ± 0.127) did not differ from that of the male (0.78; t= -1.176, p=0.305). Further, the amount of time the male and females spent thermoregulating inside rocks vs. outside did not differ. The proportion of time the male was active relative to the time with suitable Te was greater than wild males (0.45 ± 0.210) from the previous study (t= -3.850, p= 0.012). Because the time used by female and male chuckwallas to be active does not differ during summer months, chuckwalla populations may not be greatly affected by minor reductions in suitable activity time as a result of climate change.
