The Vallisneria Genetics Project - Effects of Genetic Diversity on Restoration Success

When degraded areas are restored, they need to contain an adequate species complement to withstand environmental fluctuations. All available evidence indicates that it is equally important to preserve genetic diversity within species in conservation and restoration efforts. Our project explores three levels of genetic diversity that may be important in conferring a greater chance that a restoration effort will be successful: levels of inbreeding within individuals, levels of diversity among individuals (e.g., numbers of alleles, genotypes, and phenotypes), and the adaptation of individuals to local environment.

We focus on Vallisneria americana because it was once a dominant species in the Chesapeake Bay, it is considered an important food resource for wildfowl, it does not interfere with recreational uses of waterways, and it is used in restoring freshwater portions of the Bay by a variety of groups. As with many aquatic species, V. americana is a dioecious submersed aquatic macrophyte that is capable of both clonal growth and sexual reproduction with vegetative expansion often being the dominant form of propagation. It is not known how past population bottlenecks and restoration activities may have affected the natural genetic diversity of freshwater SAV growing in the Chesapeake Bay. However, this information is needed to effectively monitor the health of this important living resource which is not stable from year to year and can conceivably re-enter a period of decline if environmental conditions worsen due to unforeseen weather events. The amount and structure of genetic diversity within and among populations of V. americana in the Chesapeake Bay will depend on a combination of relative amounts of vegetative versus sexual reproduction, patterns of seed dispersal, nature of a seed bank, and population history.

Dr. Maile Neel's lab at UMCP has collected Vallisneria americana throughout the Chesapeake Bay region. Some natural and restored populations were paired to allow comparisons of genetic diversity while controlling for differences in environmental conditions as much as possible. Collection sites represent much of the geographic extent of V. americana in the Bay to encompass a number of environmental gradients, such as salinity, temperature, nutrient regime, and depth.

Shoot tissue for genetic analysis was removed from each ramet and transported to College Park for further processing. 

Whole plants were transported to the Appalachian Laboratory’s greenhouse where they were planted in individual containers for cloning. This genotype repository has been used extensively for experiments, restoration, and education.