Thermal preferences and effects of temperature on fitness parameters of an endemic Argentinean tarantula (Grammostola vachoni)

Abstract

Mygalomorphs depend on thermal microhabitats for successful behavior, but their thermal biology is still poorly known. Grammostola vachoni Schiapelli and Gerschman, 1961 is an endemic tarantula from Argentina and it is listed as vulnerable in the IUCN Red List. However, little is known about its biology; therefore, we attempted to explore the thermal biology of juveniles and adult females of G. vachoni under laboratory conditions. We characterized the preferred temperatures, evaluated the relationship between temperature and locomotor performance, and calculated the thermal sensitivity. Individuals showed a peak temperature preference and spent 40% of the total time at 25?29 °C; we did not find any significant differences in temperature preference between juveniles and females. We found that locomotor performance is strongly affected by high temperatures. Different sprint speeds of juveniles and females were found at 5, 35, and 40 °C. The highest thermal sensitivity was recorded in the lowest temperature range and thermal sensitivity was lowest in the highest temperature ranges. Our results are relevant in the context of climate change, because thermal parameters constitute a useful tool to explore some possible effects of this change on body temperature and thus the physiological performance and vulnerability of ectotherms like G. vachoni.