A century of landscape disturbance and urbanization of the San Francisco Bay region affects the present-day genetic diversity of the California Ridgway’s rail (Rallus obsoletus obsoletus)
Fragmentation and loss of natural habitat have important consequences for wild populations and can negatively affect long-term viability and resilience to environmental change. Salt marsh obligate species, such as those that occupy the San Francisco Bay Estuary in western North America, occupy already impaired habitats as result of human development and modifications and are highly susceptible to increased habitat loss and fragmentation due to global climate change. We examined the genetic variation of the California Ridgway’s rail (Rallus obsoletus obsoletus), a state and federally endangered species that occurs within the fragmented salt marsh of the San Francisco Bay Estuary. We genotyped 107 rails across 11 microsatellite loci and a single mitochondrial gene to estimate genetic diversity and population structure among seven salt marsh fragments and assessed demographic connectivity by inferring patterns of gene flow and migration rates. We found pronounced genetic structuring among four geographically separate genetic clusters across the San Francisco Bay. Gene flow analyses supported a stepping stone model of gene flow from south-to-north. However, contemporary gene flow among the regional embayments was low. Genetic diversity among occupied salt marshes and genetic clusters were not significantly different. We detected low effective population sizes and significantly high relatedness among individuals within salt marshes. Preserving genetic diversity and connectivity throughout the San Francisco Bay may require attention to salt marsh restoration in the Central Bay where habitat is both most limited and most fragmented. Incorporating periodic genetic sampling into the management regime may help evaluate population trends and guide long-term management priorities.
Citation Information
| Publication Year | 2017 |
|---|---|
| Title | A century of landscape disturbance and urbanization of the San Francisco Bay region affects the present-day genetic diversity of the California Ridgway’s rail (Rallus obsoletus obsoletus) |
| DOI | 10.1007/s10592-016-0888-4 |
| Authors | Dustin A. Wood, Thuy-Vy D. Bui, Cory T. Overton, Amy G. Vandergast, Michael L. Casazza, Joshua M. Hull, John Y. Takekawa |
| Publication Type | Article |
| Publication Subtype | Journal Article |
| Series Title | Conservation Genetics |
| Index ID | 70182241 |
| Record Source | USGS Publications Warehouse |
| USGS Organization | San Francisco Bay-Delta; Western Ecological Research Center |
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A Century of Landscape Disturbance and Urbanization of the San Francisco Bay Region affects the Present-day Genetic Diversity of the California Ridgways Rail (Rallus obsoletus obsoletus).
Cory Overton
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Amy Vandergast
Supervisory Research Geneticist
Michael Casazza
Research Wildlife Biologist
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A Century of Landscape Disturbance and Urbanization of the San Francisco Bay Region affects the Present-day Genetic Diversity of the California Ridgways Rail (Rallus obsoletus obsoletus).
Fragmentation and loss of natural habitat have important consequences for wild populations. Reductions in population size, density and connectivity can disrupt the distribution of genetic diversity within species and negatively impact long-term viability and resilience to environmental change. Genetic assessments of population structure, diversity and gene flow can provide important insights into - Connect
Cory Overton
Wildlife BiologistEmailPhoneAmy Vandergast
Supervisory Research GeneticistEmailPhoneMichael Casazza
Research Wildlife BiologistEmailPhone