Exploring breeding season phenology of the Eastern Gray Treefrog (Dryophytes versicolor)

Abstract

Altered phenological cycles due to climate changes may affect species’ geographical distributions as the new timing of important life-history events may allow species to expand or shift their range. Insight into these processes can be gained through analyzing relationships between environmental conditions and breeding phenology of the same species at different latitudes. As climate change continues to impact species ranges, especially in variable environments, exploring what influences breeding season will help to understand ecosystem dynamics and how species can account for variable environments. I analyzed how breeding season varies in timing and duration between the northern range edge and range core of Dryophytes versicolor (Eastern Gray Treefrog, Hylidae). I found that populations at the northern range edge had a significantly shorter breeding season than the range core. This included a later onset of calling for the northern range edge and an earlier end to the calling season. Populations at the northern range edge also began calling at colder temperatures compared to those at the range core. I explored life-history trade-offs within D. versicolor to understand if reproductive investment may cause the end of breeding season. I analyzed the amount of mass lost by D. versicolor males across a breeding season in relation to when calling ended. I found that there was not a threshold mass loss in males that triggered the end of breeding season. I did confirm the presence of a reproduction-survival trade-off, as males that invested less the previous season were more likely to be recaptured in the following season. There are multiple environmental and biological factors at play that determine the timing of breeding season for D. versicolor. Further work would contribute to understanding their life history and at what scale or severity they could be impacted by future climate change.