Southeast Ecological Science Center
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Using Genetic Research to Inform Imperiled and Invasive Species Management
The long-term viability of species and populations is related to their potential to migrate, reproduce, and adapt to environmental changes. In the southeast United States, U.S. Geological Survey (USGS) scientists are providing resource managers with genetic information to improve the long-term survival and sustainability of the Nation’s aquatic species. Research focused on native and imperiled species can assess the genetic factors influencing their survival and recovery, while work on invasive species can provide information on their proliferation, dispersal, and impacts on native species.
Imperiled Native Species
Genetic diversity plays a critical role in the ability of a species to survive. A diverse gene pool can increase a population’s ability to adapt to diseases, habitat modifications, or changes in the environment, such as altered hydrology and hurricanes. Small, imperiled populations typically have reduced genetic diversity, which can increase susceptibility to disease, decrease population viability and negatively influence fitness, or the number of surviving offspring.
Quantifying the genetic diversity of a species or population is a useful first step in understanding the factors affecting imperiled species. Using nuclear DNA (deoxyribonucleic acid), scientists can identify inbred populations before physical defects are present. This type of genetic information can help managers identify whether additional conservation measures are warranted. Genetic diversity data combined with morphological data can be used to assist with taxonomic classifications, especially for species that are at risk of extinction and are undergoing conservation listing decisions, or with samples where the species is not clearly identifiable morphologically, such as in poaching cases. Another type of analysis, known as phylogenetics, can determine the evolutionary relatedness of populations, specifically useful for assisting with decisions regarding the conservation status and management of imperiled species. Similarly, geneticists can use phylogeography to address the historic processes that resulted in the geographic distribution of organisms, while landscape genetics addresses the influence of ecology and current environmental features (rivers, mountains, roads, etc.) on genetic connectivity at a finer scale.
Knowledge of population patterns across the landscape can help improve imperiled species management. For example, if populations that were once connected are now isolated or have extremely low diversity, managers may use conservation measures, such as habitat corridors, to reconnect populations and improve the viability of the species.
Genetic tools can also identify individual animals, their sex, and pedigree or familial relationships, which can provide life history information. Repeated identification of individuals over time, known as mark-recapture studies, can help with determining population sizes, trends, and survival rate estimates. This complementary approach to traditional inventory and monitoring methods can improve the time and cost effectiveness of assessing population status and trends.
Genetic tools can also be used to rapidly identify, monitor, and manage non-native species. Invasive and exotic species can potentially harm native populations, disrupt natural ecosystems, and transmit nonindigenous diseases to human and native wildlife populations.
USGS geneticists are using molecular markers to confirm the identity of invasive species and to determine the source populations for these species.
By assessing the origins of non-native species, scientists can help managers learn more about how they may have been introduced into the environment, through intentional releases or unintentional escapes, and gauge the likelihood of the population increasing and becoming established in the ecosystem. Genetic examination of gut contents can determine the native species that are preyed upon by invasive species, which helps managers assess the impact of invasives on the environment and imperiled species.
An improved understanding of genetic population dynamics can also be used to determine whether separate populations of non-native species exist in the wild. This determination can help managers target the main breeding population of invasive species for control or removal efforts.
The "First Generation” of Conservation Genetics