Thermal niche conservatism in an environmental gradient in the spider Sicarius thomisoides (Araneae: Sicariidae): Implications for microhabitat selection.

Temperature is one of the most important environmental variables for organisms, especially for ectothermic animals. In fact, ectotherms must move within a relatively narrow range of temperatures where they are able to maximize their performance. We assessed the thermal ecology of female sand spiders (Sicarius thomisoides) in Chile from separate populations along an environmental gradient and different macro habitats (coast vs. inland locations). The parameters of thermal performance curves do not vary between populations, with an average optimum temperature (T°opt) of 25.33 ± 2.65 °C, and a CT min and CT max of 6.56 ± 1.72 °C and 44.23 ± 4.92 °C, respectively. Our results show that the thermal niche in laboratory is conserved and does not vary along an environmental gradient coinciding with the temperatures selected by female spiders in their microhabitats.