Gene pool boundaries for the Yosemite Toad (Anaxyrus canorus) reveal asymmetrical migration within meadow neighborhoods

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

Submitted to: Frontiers in Conservation Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/21/2022
Publication Date: 4/1/2022
Citation: Maier, P.A., Vandergast, A.G., Ostoja, S.M., Aguilar, A., Bohonak, A.J. 2022. Gene pool boundaries for the Yosemite Toad (Anaxyrus canorus) reveal asymmetrical migration within meadow neighborhoods. Frontiers in Conservation Science. 3. Article 851676. https://doi.org/10.3389/fcosc.2022.851676.
DOI: https://doi.org/10.3389/fcosc.2022.851676

Interpretive Summary: The Yosemite toad (Anaxyrus [Bufo] canorus) is a federally threatened species of meadow-specializing amphibian endemic to the high-elevation Sierra Nevada Mountains of California. We used genetic techniques to determine if individual meadows or clusters of meadows are most correlated to population boundaries; understand among meadow toad migration; and if there are any important environmental or landscape features that help us understanding the nature of among meadow toad migration. The findings from this study can have significant utility for prioritizing the future management and conservation of this iconic California species.

Technical Abstract: The Yosemite toad (Anaxyrus [Bufo] canorus) is a federally threatened species of meadow-specializing amphibian endemic to the high-elevation Sierra Nevada Mountains of California. The species is one of the first amphibians to undergo a large demographic collapse that was well-documented, and is reputed to remain in low abundance throughout its range. Recent phylogeographic work has demonstrated that Pleistocene toad lineages diverged and then admixed to differing extents across an elevational gradient. Although lineage divisions may have significant effects on evolutionary trajectories over large spatial and temporal scales, present-day population dynamics must be delineated in order to manage and conserve the species effectively. In this study, we used a double-digest RADseq dataset to address three primary questions: (1) Are single meadows or neighborhoods of nearby meadows most correlated with population boundaries? (2) Does asymmetrical migration occur among neighborhoods of nearby meadows? (3) What topographic or hydrological variables predict such asymmetrical migration in these meadow neighborhoods? Hierarchical STRUCTURE and AMOVA analyses suggested that populations are typically circumscribed by a single meadow, although 84% of meadows exist in neighborhoods of at least two meadows connected by low levels of migration, and over half (53%) of neighborhoods examined display strong asymmetrical migration. Meadow neighborhoods often contain one or more large and flat “hub” meadows that experience net immigration, surrounded by smaller and topographically rugged “satellite” meadows with net emigration. Hubs tend to contain more genetic diversity and could be prioritized for conservation and habitat management and as potential sources for reestablishment efforts.