Research

Population and Landscape Genetics

Photo by Rav Bennett

Landscape Genetics of American Marten

We used landscape genetics to identify landscape features that facilitate or impede American marten (Martes americana) gene flow in the northeastern US. We found that forest cover, elevation, and cold temperatures facilitate gene flow, and developed land cover impedes gene flow. We used a multi-scale approach with replication to reveal site- and scale-specific patterns in our data. Finally, we used spatial analysis to predict the locations of key gene flow corridors using our landscape genetics models. This work has been published Open Access as the cover article in the April 2020 Issue of Heredity.

American Marten Population Genetics

We estimated genetic structure of marten populations at the southeastern periphery of their distribution, in Maine, New Hampshire, Vermont and New York. We discovered that a recently detected population in Vermont was likely descendant from a reintroduction attempt, which was previously believed to be unsuccessful. We also identified areas where martens may have persisted in relictual populations despite going undetected for decades. This work has been published in Conservation Genetics.

Salt Marsh Harvest Mouse Landscape Genetics

We used landscape genetics to identify landscape features that facilitate gene flow in the endangered salt marsh harvest mouse (Reithrodontomys raviventris). We found that open water and upland habitat constrained salt marsh harvest mouse gene flow. We identified a large, interconnected population across the northern marshes of Suisun Bay, which represents a stronghold of the species. This work is published in Conservation Genetics.

Dietary Metabarcoding

Diet of Juvenile Merlins in the PAcific Flyway

We used DNA metabarcoding to estimate dietary patterns in juvenile merlins (Falco columbarius) migrating along the Pacific flyway. We found that merlin diet shifted in response to seasonal and interannual changes in songbird abundance, characterized by pulses of irruptive migrants in an irruptive year for cone crop-dependent species, such as pine siskin and red-breasted nuthatch, and seasonal pulses of regular migrants, such as savannah sparrow. This work is published in Ibis.

Diet Composition Analysis of Amargosa Vole

The Amargosa vole (Microtus californicus scirpensis) is an endangered species endemic to extremely rare wetland habitat along a single river corridor in the Mojave Desert. These wetlands are near-monocultures of three-square bulrush. Consequently, Amargosa voles have been presumed to rely entirely upon bulrush for habitat and forage. We used a combination of nutritional analyses, microhistology, and DNA metabarcoding to evaluate the composition of Amargosa vole diet. We found a greater diversity of dietary items than expected, including 14 families of plants. The nutritional analysis suggested that bulrush alone was unlikely to support vole survival and reproduction, substantiating the diversity of diet items detected. This work is published Open Access in PLoS ONE.

Dietary Characterization of Salt Marsh Harvest MIce

The salt marsh harvest mouse is an endangered species restricted to coastal wetlands in the San Francisco Estuary. Salt marsh harvest mice have historically been considered a dietary specialist on pickleweed (Salicornia pacifica), and little is known about the diet of potential competitors. We used DNA metabarcoding to characterize the diet of salt marsh harvest mice and three sympatric rodents. We found that salt marsh harvest mouse diet was diverse but dominated by pickleweed and non-native saltbush (Atriplex prostrata). Salt marsh harvest mouse diet was narrowest in fall, when favored foods were seeding, and broadest in spring, when preferred foods were dormant. Salt marsh harvest mouse diet was narrower than sympatric rodents, highlighting their specialization on marsh plants and relative avoidance of adjacent upland vegetation. This work is published Open Access in Ecology and Evolution.

Landscape Ecology and Habitat Modeling

Distribution and Habitat Connectivity for American Marten

We estimated marten occupancy in the northeastern US from a diverse panel of local expert-elicited information. We identified significant relationships between estimated marten occupancy and tree canopy cover, spruce-fir land cover, temperature, elevation, and roads. Additionally, we used results from occupancy models to identify key movement corridors to connect fragmented populations throughout the northeastern US. This work has been published in Animal Conservation.

Patch Occupancy modeling of Salt Marsh Harvest Mice

We used non-invasive genetic surveys for salt marsh harvest mice at numerous habitat patches throughout the San Francisco Estuary. Then, we used occupancy modeling to determine the effect of spatial characteristics, such as patch size and connectivity, on salt marsh harvest mouse occupancy. This work is in review for publication.

Genetic/Genomic Tool Development

Non-Invasive Genetic Surveys for Small Mammals

Non-invasive genetic surveys are a powerful tool for wildlife management and conservation, but are seldom applied to small species due to logistical challenges of collecting non-invasive genetic material. We developed a novel approach using bait stations to collect rodent fecal samples and a genetic test to conduct species identification. This work is published in the Journal of Mammalogy.