Landscape genetics of a sub-apline toad: climate change predicted to induce upward range shifts via asymmetrical migration corridors

Authors: MAIER, PAUL - San Diego State University; VANDERGAST, AMY - Us Geological Survey (USGS); Ostoja, Steven; AGUILAR, ANDRES - California State University; BOHONAK, ANDREW - San Diego State University

Submitted to: Heredity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/25/2022
Publication Date: 9/8/2022
Citation: Maier, P., Vandergast, A., Ostoja, S.M., Aguilar, A., Bohonak, A. 2022. Landscape genetics of a sub-apline toad: climate change predicted to induce upward range shifts via asymmetrical migration corridors. Heredity. https://doi.org/10.1038/s41437-022-00561-x.
DOI: https://doi.org/10.1038/s41437-022-00561-x

Interpretive Summary: Climate change is expected to force significant shifts for many species of wildlife across California. The Yosemite toad (Anaxyrus [Bufo] canorus) is a species of meadow-specializing amphibian endemic to the high-elevation Sierra Nevada Mountains of California. Climate change is expected to have a major hydrological impact on the species’ wet meadow habitat, yet our understanding of current climatic impacts to meadow connectivity via tadpole recruitment and adult dispersal is not well understood. In this project we identified the importance of numerous snowpack-related features, such as water runoff and groundwater recharge. Our results show a likely upward elevational shift for this already high elevation species, as measured by anticipated genetic movement.

Technical Abstract: Climate change is expected to have a major hydrological impact on the core breeding habitat and migration corridors of many amphibians in the twenty-first century. The Yosemite toad (Anaxyrus canorus) is a species of meadow-specializing amphibian endemic to the high-elevation Sierra Nevada Mountains of California. Despite living entirely on federal lands, it has recently faced severe extirpations, yet our understanding of climatic influences on population connectivity is limited. In this study, we used a previously published double-digest RADseq dataset along with numerous remotely sensed habitat features in a landscape genetics framework to answer two primary questions in Yosemite National Park: (1) Which fine-scale climate, topographic, soil, and vegetation features most facilitate meadow connectivity? (2) How is climate change predicted to influence both the magnitude and net asymmetry of genetic migration? We developed an approach for simultaneously modeling multiple toad migration paths, akin to circuit theory, except raw environmental features can be separately considered. Our workflow identified the most likely migration corridors between meadows and used the unique cubist machine learning approach to fit and forecast environmental models of connectivity. We identified the permuted modeling importance of numerous snowpack-related features, such as runoff and groundwater recharge. Our results highlight the importance of considering phylogeographic structure, and asymmetrical migration in landscape genetics. We predict an upward elevational shift for this already high-elevation species, as measured by the net vector of anticipated genetic movement, and a north-eastward shift in species distribution via the network of genetic migration corridors across the park.