Hybridization Between an Invasive Exotic and a Declining Native Amphibian: Molecular Characterization, Ecological Dynamics, and Genetic Remediation

EPA Grant Number: R828896
Title: Hybridization Between an Invasive Exotic and a Declining Native Amphibian: Molecular Characterization, Ecological Dynamics, and Genetic Remediation
Investigators: Shaffer, Howard B. , Koenig, Walter D. , Voss, S. Randal , Fitzpatrick, Benjamin
Institution: University of California - Davis , University of Kentucky , University of California - Berkeley
Current Institution: University of California - Davis , University of California - Berkeley , University of Kentucky
EPA Project Officer: Packard, Benjamin H
Project Period: August 20, 2001 through August 19, 2004 (Extended to August 31, 2005)
Project Amount: $433,708
RFA: Exploratory Research to Anticipate Future Environmental Issues (2000) RFA Text |  Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , Water , Aquatic Ecosystems


This project will characterize the interactions between an introduced exotic salamander (the tiger salamander Ambystoma tigrinum) and a native, declining, endemic species (A. californiense) in the central California landscape. Our preliminary work demonstrates that 1) in the region of co-occurrence, the two species interbreed, resulting in a severe case of genetic "biopollution", and 2) that interbreeding is more complete in disturbed compared to natural pond habitats, suggesting that habitat restoration may be an effective, proactive remediation.

This research aims to quantify the extent of genetic invasion of an exotic species, develop a full set of informative molecular markers, and conduct detailed genetic and demographic analyses to identify the extent of genetic biopollution and reduce introduced exotic genes. This work provides the first complete assessment of the risk involved for this species as well as a novel strategy for reversing the widespread problem of genetic biopollution in endangered species.


Our approach will 1) develop a panel of 10-20 mapped nuclear markers to quantify a fine-scale hybrid index, 2) use these markers to determine the geographic extent of hybrid introgression and the concordance of introgression across genes, 3) collect key demographic information in the field and laboratory to quantify differences among pure and hybrid salamanders, 4) test multiple ponds and genes to investigate the correlation of hybrid inviability with ecological pond characteristics, and 5) conduct a preliminary field experiment to investigate the efficacy of one strategy to reduce or eliminate introduced exotic genotypes.

Expected Results:

Our expected results include a complete characterization of the demographic, genetic and geographic scope of this biological invasion, the ecological conditions most favorable for successful remediation, and a quantitative assessment of one strategy for removing introduced genes from the landscape.

Publications and Presentations:

Publications have been submitted on this project: View all 11 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 3 journal articles for this project

Supplemental Keywords:

ecological effects, sensitive populations, genetic polymorphisms, aquatic ecosystems, restoration, conservation, ecology, genetics, surveys, California, CA., RFA, Health, Scientific Discipline, Geographic Area, Ecosystem Protection/Environmental Exposure & Risk, Genetics, Ecosystem/Assessment/Indicators, exploratory research environmental biology, State, Environmental Microbiology, Ecological Effects - Environmental Exposure & Risk, Susceptibility/Sensitive Population/Genetic Susceptibility, Monitoring/Modeling, Ecological Risk Assessment, genetic susceptability, Biology, Futures, Exp. Research/future, Ecological Indicators, ecological effects, extinction risk, biodiversity, endangered species, biopollution, genetic predisposition, molecular characterization, amphibian, conservation, animal models, invasive species, exotic genotypes, genetic remediation, California (CA), hybridization, ecological dynamics, demographic analyses, exotic species, futures research, interbreeding

Progress and Final Reports:

  • 2002
  • 2003 Progress Report
  • 2004 Progress Report
  • 2005
  • Final Report