Randall Hughes Research

Interactions between Spartina genotypic diversity and associated species

Salt marshes are the dominant intertidal habitat along the Gulf and Atlantic Coasts of the United States, and they provide numerous valuable ecosystem services including buffering against erosion, filtering nutrients and sediments from terrestrial run-off, and providing nursery and refuge for economically- and ecologically-important species. Because of the high physical stress of the marsh environment, plant species diversity in this ecosystem is typically low, which is predicted to increase the relative importance of plant genetic diversity.

Salt marshes along the Gulf Coast are often dominated by the clonal plant Spartina alterniflora. Spartina is known as a “foundation species” because it provides the basis of the marsh habitat in these regions.  In keeping with evidence from dominant species in other systems, Spartina exhibits significant genetic variation in a wide variety of ecologically-important traits such as growth rate, morphology, and competitive ability.  This genetic variation is a prerequisite for ecological effects of genetic diversity, and coupled with low plant species diversity and Spartina’s important role as a habitat provider, makes this an ideal system for investigating the relationship between genotypic (i.e., clonal) diversity and associated species identity/diversity, as well as their cumulative impact on overall system productivity.  In fact, although not demonstrated in full, there is an abundance of evidence suggesting a relationship between Spartina genetic variation and the community of organisms that depend on marsh habitat.

I am currently conducting a combination of surveys and experiments to investigate each unidirectional relationship between Spartina genotypic variation and the community of marsh-associated species, as well as the potential for reciprocal effects between the two.  Specifically, I am:  (1) examining the relationship between Spartina genetic diversity and associated species abundance and diversity at multiple spatial scales in natural marsh populations along the Gulf Coast of Florida; (2) quantifying the degree of morphological variation among Spartina genotypes grown in a common environment; (3) conducting a series of experiments to investigate the bi-directional relationship between individual Spartina genotypes and key associated species; (4) experimentally examining the independent and interactive effects of Spartina genetic diversity and associated species presence on marsh productivity.

This project is generously funded by the FSU Office of Research and the National Science Foundation.