Meeting Abstract
Winter provides many challenges for terrestrial arthropods. Low temperature, freeze-thaw cycles, precipitation and extreme weather events negatively impact the survival and fitness of these organisms. Most arthropods overwinter in a dormant diapause state and cease functions like activity, growth, and feeding. However, a select few arthropods remain active during winter, and the ability to maintain activity and continue foraging and growing are thought to provide a selective advantage by enhancing spring reproduction. In this study, we investigated physiological and biochemical adaptations to winter conditions in a winter active wolf spider, Schizocosa stridulans. For this species and other winter active arthropods, winter activity requires the capacity to maintain locomotion at low temperatures, preserve energy balance with limited food availability, and tolerate extreme cold events. We hypothesized that winter activity in S. stridulans is accompanied by a low critical thermal minimum (CTmin) and the ability to grow and maintain energy balance in the winter. We tested CTmin of spiders kept in experimental incubators in the lab. It is much lower than other recorded spiders or insect taxa, averaging -4˚C. We show that these spiders are able to continuing growing throughout the winter, with a field-collected dataset, and that nutrient profiles reflect that growth with increased levels of protein across the winter months and a decrease in lipids. In ongoing analyses, we are using metabolomics to identify putative cryoprotectants and other metabolic changes that may support winter activity. Taken together, this work provides critical insights into the physiological and biochemical adaptations that permit this spider to be among the small handful of species that remain active in winter.
