Research

Outline: California red-legged frogs (Rana draytonii; CRLF) were once ubiquitous accross the Santa Monica Mountains but are now almost locally extirpated. In order to ensure the long-term viability of this population, the National Park Service has been reintroducing this population to nearby streams in their historic range. However, managers of the species do not currently understand to what extent populations harbor deleterious variation as a result of inbreeding or how this harmful variation will affect population fitness in the future. This project will address the following hypotheses:

H1: Populations of CRLF in the Santa Monica Mountains have higher levels of inbreeding and genetic load as a result of long-term small population size
H2: CRLF historical demography will recapitulate a history of human disturbance, with a decline in CRLF effective population size around 100 years ago

Outline: Land use alteration is damanging to many species in the Santa Monica Mountains. In galliforms (ground birds including pheasants and quail), it is thought to lead to the creation of isolated metapopulation and overall decreased population viability (Burger 2002). For example, Northern bobwhite quail increase dispersal distance as interpatch habitat distance increases but go to local extinction when the distance between marginal habitat patches is too great (Fies et al. 2002). The purpose of this study is to use high coverage whole genome sequencing across the Santa Monica Mountains to understand the extent to which metapopulation dynamics exist in Southern California populations of quail. Specifically, this project will address the following research hypotheses:

H1: Quail populations located on either side of a roadway will exhibit greater genetic differentiation when compared to populations of equal distance on the same side of the roadway
H2: Genetic differentiation of quail populations on either side of a roadway will be positively correlated with the traffic volume of that roadway
H3: Quail populations that are surrounded by impervious habitat including major roadways and urban centers will exhibit signs of increased genetic load and inbreeding when compared with nearby populations without such constraints to movement and gene flow

Outline: Yuma Myotis (Myotis yumanensis, MYYU) is an abundant and widely distributed bat species in California, yet little empirical data exist on MYYU movement and genetic structure across the landscape. Baseline genomic data is key to conserving MYYU populations from the emerging threat of White Nose Syndrome (WNS) in California. For example, research in the Eastern U.S. has shown that topography affects the movement of bats across the landscape, ultimately determining the spread of WNS (Miller-Butterworth et al. 2014; Vonhof et al. 2015). Data on the movement of bats between colonies in California could facilitate predictions regarding how WNS will spread and the landscape features (e.g. mountain ranges) that might serve to insulate colonies from the pathogen. Therefore, this study has the following goals:

1) Provide baseline data on population structure and genetic units for conservation across the state
2) Characterize patterns of gene flow in relation to landscape features
3) Estimate demographic parameters of MYYU populations using coalescent simulations to provide information on historical fluctuations in effective population size
4) Use genetic-environment association methods to characterize genomic variation consistent with local adaptation.

Louisiana red swamp crayfish (Procambarus clarkii) were introduced into the Southern California in the 1960s as a bait fish. Today, they are common throughout the streams of the Santa Monica Mountains. Invasive crayfish pose a problem to native biodiversity as they prey upon most stream organisms. Crayfish are also associated with decreased water quality, stream stability, and even higher abundance of mosquitos! In order to control this problematic species, I've worked on collaborative research to optimize crayfish trapping and removal. This research resulted in a publication in Management of Biological Invasions and Freshwater Science (See Publications).