Microsatellite Analysis of Quagga Mussel Genetic Variability in the Colorado River System

Project ID: 6712
Principal Investigator: Sherri Pucherelli
Research Topic: Invasive Species
Funded Fiscal Years: 2016
Keywords: invasive mussels, genetic analysis, habitat suitability

Research Question

The objective of this research is to determine if quagga mussels collected within the Colorado River System exhibit genetic diversity. This research proposal builds on two previous research studies that were designed to determine the causes of reduced mussel settlement at Imperial Dam in comparison to upstream sites on the Lower Colorado River. The water quality of each reservoir along the lower Colorado River is unique and it is possible that established mussel populations are adapting to these variable conditions. The quality of Reclamation waters will continue to shift in the presence of continued drought and climate change. When faced with these changes, aquatic organisms such as mussels must either have a wide range of tolerances or possess the ability to adapt in order to maintain or expand populations. Microsatellite analysis can provide information about genetic diversity within a species, including gene flow, genetic variants, and population structure. Understanding the genetic variability within quagga mussel populations throughout the Western United States can provide Reclamation with valuable information that may help predict future mussel distribution patterns, potential control points and impacts to Reclamation waters.

Need and Benefit

Reclamation is currently challenged with management of invasive mussel infestations at many facilities throughout the West. Challenges also exist for managers of facilities in areas where mussel infestations have not yet occurred in preventing and/or preparing for mussel establishment. Several studies have investigated the limits of water quality parameters associated with the quagga mussel's ability to sustain and reproduce. Published water quality parameters related to the proliferation of invasive mussels have proven to be inaccurate in the Western U.S. in several instances (i.e. highly infested water bodies with water quality features outside of the published parameters). These findings emphasize the notion that the current understanding of water quality parameters associated with invasive mussel habitat is limited or that local adaptations may be occurring. However, the ability for a quagga mussel population genetics to change may alter their suitable habitat parameters, allowing for continued range expansion or modification. Information regarding the genetic diversity and distribution of invasive mussels will provide better estimates of habitat suitability, which will be highly useful to Reclamation managers in preparing for, and preventing or minimizing the potential for infestation. Enhanced confidence regarding suitability levels would allow prioritization of budget allocation and decision processes for water bodies that are at high risk for problematic infestations.

Preliminary genetic analysis of quagga mussels in the West conducted by the University of Arizona has found a significant degree of diversity, even within the same system. The habitat variation seen within the Lower Colorado River system may be associated with this genetic variability. Accurate information regarding the level of suitability for water bodies to support invasive mussel populations is highly useful to Reclamation managers in preparing for, and preventing or minimizing the potential for infestation. Certainty in the knowledge of suitability levels would allow prioritization of budget allocation and decision processes for water bodies that are at high risk for problematic infestations. A greater understanding of quagga mussel genetic variation may provide insight into genetic vulnerability or genes that can be targeted for control purposes. Without a clear understanding of a population's genetic diversity it is possible that control measures may fail to target the entire population.

Contributing Partners

Contact the Principal Investigator for information about partners.

Research Products

Bureau of Reclamation Review

The following documents were reviewed by experts in fields relating to this project's study and findings. The results were determined to be achieved using valid means.

Microsatellite Analysis of Quagga Mussel Genetic Variability in the Colorado River System (final, PDF, 510KB)
By Sherri Pucherelli
Publication completed on September 30, 2016

Large populations of invasive quagga mussels (Dreissena rostriformis bugensis, Andrusov, 1897) are present in reservoirs along the lower Colorado River. These reservoirs have unique water quality characteristics which raised questions about the extent of gene flow and genetic divergence among those populations. In this study, we examined the neutral genetic structure among six populations from different reservoirs along the Colorado River in the southwestern United States. Individual quagga mussels were genotyped at 10 microsatellite DNA loci to analyze patterns of genetic diversity and population structure. Overall genetic divergence among the populations was negligible and populations at a single reservoir were not significantly genetically differentiated from the group. Some population pairings did exhibit significant, if slight, genetic differentiation, and there was a moderate pattern of isolation-by-distance.

Microsatellite Analysis of Quagga Mussel Genetic Variability in the Colorado River System (final, PDF, 304KB)
By Sherri Pucherelli
Publication completed on September 30, 2016

Large populations of invasive quagga mussels (Dreissena rostriformis bugensis, Andrusov, 1897) are present in reservoirs along the lower Colorado River. These reservoirs have unique water quality characteristics which raised questions about the extent of gene flow and genetic divergence among those populations. In this study, we examined the neutral genetic structure among six populations from different reservoirs along the Colorado River in the southwestern United States. Individual quagga mussels were genotyped at 10 microsatellite DNA loci to analyze patterns of genetic diversity and population structure. Overall genetic divergence among the populations was negligible and populations at a single reservoir were not significantly genetically differentiated from the group. Some population pairings did exhibit significant, if slight, genetic differentiation, and there was a moderate pattern of isolation-by-distance.

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Last Updated: 6/22/20