Salamanders are secretive, yet fascinating animals with surprisingly elaborate types of chemical communication (see this YouTube channel for examples of salamander behavior that involves chemical signaling). Karen and departmental colleague John Reiss have funding to examine olfactory morphology and gene expression patterns across eight plethodontid salamander species with a wide range of life histories, ranging from typical larvae with metamorphosis, to direct development with no free-living larval stage, to secondarily re-evolved larvae. This work was funded by an NSF IOS grant ("Smelling in water and air: Evolution of olfaction in plethodontid salamanders").

Another avenue of our research seeks to understand exactly how chemical signals can impact salamander behavior. We are testing whether pheromone application changes a receiver's preference for certain conspecific odors, as well as how the animals behave during courtship interactions. These behavioral changes can have profound effects on the reproductive success of the signalers and often drive rapid evolutionary change in pheromone composition.

Amphibians are experiencing population declines across the globe. Understanding the diversity and distribution of amphibians is critical for monitoring and preserving evolutionarily distinct groups. Our lab is involved in several collaborative efforts to better understand the status of amphibians with ranges in northern California. Funding for these projects is has been provided by the U.S. Bureau of Land Management, Save the Redwoods League, and the Northern California Herpetological Society.

One specific project focuses on determining the evolutionary relationships among populations of two divergent amphibian species: Southern Torrent Salamanders (Rhyacotriton variegatus) and Tailed frogs (Ascaphus truei). Because morphological identification is sometimes ambiguous and can mask underlying signatures of divergence, we are using population genetics to answer questions like how much genetic and morphological diversity is harbored across the range of these species? 

We are also exploring the consequences of interspecific competition between two closely related species of salamandrid newts, Taricha torosa and T. granulosa. These coexisting newt species are almost wholly allopatric along a north-south axis but can be found in sympatry in a narrow, probably primordial contact zone in coastal Central California where their ranges overlap. Our goal is to investigate how intra- and interspecific competition impact larval development (including body size, growth and larval period) as well as compare the development of allopatric and sympatric populations.