Meeting Abstract
The interbreeding of North American flying squirrel species is among the first contemporary examples of climate change-induced hybridization. Recent climate warming has caused the southern flying squirrel (Glaucomys volans) to expand its range northward, increasing sympatry with the northern flying squirrel (Glaucomys sabrinus). Flying squirrels are active in winter and share nest cavities to ensure survival in cold climates. We tested the hypothesis that cold temperatures lead to interspecific social nesting in the flying squirrel hybrid zone, a process that could facilitate hybridization since mating in flying squirrels occurs in late winter. We also tested whether differences in torpor use between flying squirrel species would make torpor a costly strategy in heterospecific nest groups compared to conspecific groups. Contrary to our prediction, the frequency of interspecific nesting did not increase with decreasing ambient temperature. Instead, G. volans chose to nest with conspecifics regardless of temperature, and G. sabrinus usually preferred to nest alone. While flying squirrels used torpor in winter, neither species used torpor when exposed to cold conditions during the summer months. Flying squirrels may only be physiologically capable of torpor in cold seasons; our continued research is evaluating these seasonal differences in torpor use. Identifying the causal mechanisms and the consequences of hybridization may facilitate the prediction of the future extent of hybridization in Glaucomys species, as well as the larger impact on biodiversity resulting from rapid rates of global change.
