Drawing Boundaries with DNA to Improve Conservation
May 17, 2020 at 3:20pm
Foothill Yellow-legged Frogs have begun to spawn, laying small snow-globe sized egg masses in streams and rivers. They are one of the few stream-breeding frogs endemic to California and Oregon. This species is a good indicator of stream health because they link aquatic and terrestrial ecosystems and are strongly tied to natural seasonal cues associated with local hydrology. Historically, they occurred in streams and rivers throughout California and Oregon, but, as with many amphibians, they have precipitously declined in many parts of their range due to river regulation, habitat loss, and disease.
First petitioned for listing under the California Endangered Species Act (CESA) in 2016 by the Center for Biological Diversity, the California Fish and Game Commission recently listed Foothill Yellow-legged Frogs (Rana boylii) in February 2020. But unlike other species listed under CESA, Foothill Yellow-legged Frogs are one of the first species where genetic data were used to introduce more nuance into the regulatory process. Only a few other species have used a genetic basis to identify groups for listing under the CESA. For example, Coho Salmon Oncorhynchus kisutch (listed in 1995) used a single status listing for the species based on existing genetic data. Similarly, the Fisher (Pekania pennanti) was also listed/not listed using evolutionarily significant units (ESUs), but the species is extremely geographically separated, unlike the historically wide-ranging Foothill Yellow-legged Frog. For Foothill Yellow-legged Frogs, different genetically distinct groups were given different listing status (Threatened, Endangered, or listing not warranted at this time). This listing is not an endpoint, it reflects successful collaboration between researchers and regulators to provide a pathway to better prioritize long-term management and conservation of one of California’s iconic species.
While protecting and conserving one of our few native frog species is important, using the same uniform listing and management strategy for every frog population in California may not be practical. The Foothill Yellow-legged Frog has a large range that historically encompassed most of California, thus a blanket approach to listing and conservation management across the state may not be very effective. Different regions of the state have different impacts on the species; therefore it makes sense and is likely more effective and cost-efficient to manage conservation at a regional scale. A more nuanced approach also avoids placing a regulatory burden on entities in areas where the species appears to be doing well. Finding options to build more flexibility into the system we use to manage and conserve our natural resources is important for long-term success. The crux of this success is best illustrated by a deceptively straightforward map (Figure 2). Despite its simplicity, this map is a result of several years of genetic research and collaboration between multiple agencies and universities. Its use in the state listing process is a relatively novel application of conservation genetics.