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Contributed Poster

Session: Evolution

PS 9-110 - Temporal Effects on Gene Flow Within the Santa Monica Mountains

Monday, August 7, 2023
5:00 PM – 6:30 PM PDT
Location: ESA Exhibit Hall
Amphibian population responses to climate change are complex and often depend on species-specific life history attributes. One critical long term challenge for effective conservation is understanding the population genetic consequences of climate change, including how extreme climate events might impact gene flow. We evaluated the population genetics of an ecological generalist tree frog (Pseudacris regilla) that breeds across streams, ponds and vernal pools in Santa Monica Mountains National Recreation Area, the largest urban national park in the world, to identify the genetic consequences of recent extreme drought and record heat waves between 2010 and 2018. We collected restriction site-associated digestion (3RAD) data from 163 (2010) and 223 (2018) tadpoles collected from 25 breeding sites throughout the park (n = 386 individuals and 2,663 unlinked SNPs). Admixture and fastStructure detected no geographic genetic structure in either dataset, in sharp contrast to the deep structure found in co-distributed stream-breeding amphibians. However, among-site pairwise Fst values calculated separately for our 2010 and 2018 P. regilla data revealed marked increases in pairwise Fst values. These results indicate that a generalist life history strategy may have benefited P. regilla historically, allowing the species to find and utilize suitable breeding habitat, but the combined effects of drought and heat waves evidently led to reduced movement and reproduction over the xeric park landscape during the last decade. In the context of extreme climate events, even common, generalist amphibian species may be quickly impacted by the combined effects of drought and rapidly rising temperatures, and as such, may require tailored management strategies.