Projects
My interdisciplinary, collaborative research spans taxa from frogs to grizzly bears. My mixed-methods approaches are aimed at solving a range of conservation challenges.
California red-legged frog with transmitter released in Yosemite Valley, Yosemite National Park.
Amphibian Reintroductions
Many species of amphibians globally have experienced severe declines, and in western North America, several species have declined significantly. Well-planned reintroductions can contribute to the recovery of threatened amphibians.
I conduct research and monitoring for amphibian reintroduction planning and implementation in California, directly linking conservation science and practice. The two focal species for this work are the California red-legged frog (Rana draytonii) and the foothill yellow-legged frog (Rana boylii).
Publications from my research with the California red-legged frog reintroduction in Yosemite National Park have been published in PLOS ONE (2020), Ecosphere (2022), Animal Conservation (2023), and Northwestern Naturalist (2023). More publications are forthcoming in collaboration with Santa Monica Mountains National Recreation Area, U.S. Forest Service, U.S. Fish and Wildlife Service, and U.S. Army.
Foothill yellow-legged frog conservation
Foothill yellow-legged frog, Rana boylii. Photo credit: Andrea Adams
Native only to California and Oregon, foothill yellow-legged frogs have declined from over half of their range. Flow alteration, invasive species, drought and disease can act synergistically to exacerbate their decline.
Ongoing work addresses the feasibility of reintroducing the species from portions of the range where it has been nearly extirpated, as well as evaluating other interventions to help the species recover. I use a combined, mixed-methods approach including environmental DNA, visual encounter surveys, habitat assessments, in situ rearing, and translocations to accomplish these goals.
A portion of my foothill yellow-legged frog research has been published in Ecosphere (2017), Ecology and Evolution (2017), and Ecohydrology (2022), with more forthcoming in 2024.
Collaborators and funding partners: U.S. Fish and Wildlife Service, California Department of Fish and Wildlife, U.S. Geological Survey, Cornell University, University of Texas at Austin, and Washington State University.
Disease Ecology of Amphibians in Baja California, Mexico
California red-legged frog in Baja California.
Many parts of the world are undersampled for the often-deadly fungal amphibian pathogen, Batrachochytrium dendrobatidis (Bd).
In Baja California, my collaborators monitor a suite of amphibian species in different habitat types at a range of elevational gradients in Baja California, and we characterize trends in Bd distribution and prevalence in the region. The sampling area is home to an isolated population of threatened California red-legged frogs (Rana draytonii).
Results from this work have been published in Diseases of Aquatic Organisms (2018) and Global Ecology and Conservation (2022).
Collaborators: Anny Peralta-Garcia, Carlos Alberto Flores-López, Jorge H. Valdez Villavicencio, Cherie Briggs
Historical Grizzly Diet in California
Ursus collection at the Los Angeles Museum of Natural History's La Brea Tar Pits.
Grizzlies are known for their varied, omnivorous diets; however, most of the research on grizzly diets in North America is focused on where the species is still present.
Led by Alexis Mychajliw, this project used stable isotope analysis of California grizzly bones archived in natural history museum collections. Our primary goal was to examine the diet of California grizzlies before they were extirpated 100 years ago, to better understand how reintroduced grizzlies may use the current California landscape nutritionally. This research was published in the Proceedings of the Royal Society B and was covered by The Atlantic, Los Angeles Times, and Live Science.
This is one of many subprojects of the California Grizzly Research Network at the University of California, Santa Barbara. You can learn more about the questions we address in the research network by reading our paper in Trends in Ecology and Evolution (2020).
Detecting DNA from formalin-fixed museum specimens
Rana collections at the University of Michigan.
Optimizing techniques is an essential component underlying ecological research. As new technologies are developed, often well-established protocols are continually used when it is possible to make changes to improve their precision.
Museum specimen collections provide indispensable repositories of information that only need to be unlocked with effective technologies and refined methods. I tested various methods of detecting Bd DNA from formalin-fixed specimens using qPCR, and found that changing to a more efficient DNA extraction method can improve DNA detection by 40%. The results of this work were published in PLoS ONE (2015).
Southern California Amphibian Declines
Arroyo toad, Anaxyrus californicus.
California and western North America are hotspots for endemic biodiversity, and amphibians are no exception. Southern California's Mediterranean climate--characterized by cool, wet winters and warm, dry summers--makes it a unique place to examine amphibian assemblages and their responses to various stressors.
Mediterranean streams in particular are highly sensitive to anthropogenic change. Many of the amphibian species native to southern California have declined substantially, but none is more stark than that of the foothill yellow-legged frog (Rana boylii), which went from very abundant to undetectable in a period of less than 10 years.
I used a mixed-methods approach, including interviews with experts and sampling of natural history collections, to examine the timing and causes of amphibian declines in southern California, including disease and rapid land use change. Results of this work were published in the journal Ecology and Evolution (2017), and I summarized the project in a blog post.