torquatus is restricted by precipitation and by the effect of lower temperatures on their time of activty and climate warming could lead to range expansion.
Activity time adds important information to distribution modeling and should be considered as a predictor in studies of the distribution of ectotherms. Precipitation ranked higher than thermally related predictors. Thermoregulation simulations did not improve model accuracy. Estimates made using the central 90% of temperatures measured in a thermal gradient as the temperature range for activity also ranked higher than environmental temperatures.
We compared 105 estimates of activity time, resulting from the combination of four methodological decisions: 1) how to estimate daily environmental temperature variation (modeling a sinusoid wave ranging from monthly minimum to maximum temperature, extrapolating from operative temperatures measured in field or using biophysical projections of microclimate)? 2) In which temperature range are animals considered active? 3) Should these ranges be determined from body temperatures obtained in laboratory or in field? And 4) should thermoregulation simulations be included in estimations? We show that models using estimates of activity time made with the sinusoid and biophysical methods had higher predictive accuracy than those using environmental temperatures alone. We compare the ability of environmental temperatures and estimates of activity time to predict the geographic distribution of a tropical lizard, Tropidurus torquatus.
Estimates of activity time might enhance our ability to predict suitable areas for species’ persistence in face of climate warming, compared to the exclusive use of environmental temperatures, without considering thermal tolerances. Time available to perform those activities is determined by thermal tolerances and environmental temperatures.
Environmental temperatures influence ectotherms’ physiology and capacity to perform activities necessary for survival and reproduction.
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