Intraspecific Variation in the Thermal Biology of <I>Rabidosa rabida</I> (Araneae: Lycosidae) (Walckenaer) From the Mountains of Arkansas

Abstract

Temperature affects all levels of biological organization and multiple aspects of ecological performance and fitness. Descriptions of thermal biology are, therefore, essential pieces of information for studying ecology in varying thermal environments. This paper describes the thermal biology of the spider Rabidosa rabida by using three common descriptive measures. Spiders were collected from two populations on mountains in Arkansas that share similar climate and vegetation. Maximum sprint speed across temperature was used to calculate an estimate of thermal sensitivity of locomotor ability. Spiders were placed in a thermal gradient to determine thermal preference. Spiders' body temperatures were increased or decreased until the ability to move was lost. Results were compared between the populations to describe intraspecific variation. Maximum sprint speed increased across temperatures showing moderate sensitivity (Q(10 all spiders) = between 1.74 and 2) except at the highest temperatures in males, and the lowest temperatures in both sexes. Maximum sprint speeds differed between populations (P < 0.05). The critical thermal maximum was shown to be 42.9°C ± 0.70. The critical thermal minimum was estimated at 0°C. Thermal preference of R. rabida was determined to be 31.9°C ± 0.44 showing no significant variation between populations. This study provides a first description of thermal biology in an ecologically important spider, and shows evidence of variation between thermal biology measures between populations with similar climate but no gene flow. Having adapted to various and changing conditions in the past, this spider and others like it can provide many ecologically and evolutionarily interesting lines of inquiry.