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Grantee Research Project Results

Historical Introductions and Population Dynamics of the Widely Introduced Salt Marsh Anemone Nematostella vectensis in Temperate Salt Marshes

EPA Grant Number: F5E11155
Title: Historical Introductions and Population Dynamics of the Widely Introduced Salt Marsh Anemone Nematostella vectensis in Temperate Salt Marshes
Investigators: Reitzel, Adam M.
Institution: Boston University
EPA Project Officer: Cobbs-Green, Gladys M.
Project Period: September 6, 2005 through September 5, 2007
Project Amount: $96,354
RFA: STAR Graduate Fellowships (2005)
Research Category: Academic Fellowships

Description:

Objective:

Nematostella vectensis , an estuarine, infaunal sea anemone, is one of several hundred coastal species that have been introduced in the past two centuries to non-native geographic regions in North America and abroad. For Nematostella, a number of populations, specifically those along the Pacific coast of North America and in England, are unlikely to have occurred by natural dispersal mechanisms and presumably represent recent introductions from the Atlantic coast of North America. The first objective of this research is to determine the number and source of these introductions using population genetic markers from individuals collected from populations throughout Nematostella’s range. Secondly, Nematostella is capable of both sexual and asexual reproduction, which may have a striking effect on the genetic structure of populations that have resulted from recent colonizations. The ability of Nematostella to establish stable populations through clonal expansion by asexual reproduction suggests that clonality is likely to be a dominant characteristic of peripheral populations. As such, this research will also quantify the frequency of genotypically identical individuals in each collected population.

Approach:

I will collect individual anemones from sites throughout the global range of the species, genotype all individuals by generating amplified fragment length polymorphism (AFLP) fingerprints, and subject resulting genetic data to appropriate analyses for genetic relatedness as well as clonality. Nematostella has most commonly been reported from tidally restricted pools in salt marsh and lagoonal habitats. First, I will conduct thorough surveys of sites from which anemones have been either previously reported or sites of interest (32 sites in 22 states) by sifting sediment over 1-mm 2 mesh filters. Secondly, I will genotype each individual collected. The ease with which numerous markers can be generated by the AFLP protocol will contribute to the identification of:

  1. genetic relatedness of individuals both within and between geographic locations as well as genetic diversity within populations
  2. and clonal populations and frequency of asexual versus sexual reproduction, as the large number of markers will facilitate analysis of multilocus disequilibrium.

My study will characterize the distribution and genetic structure of an estuarine anemone, Nematostella vectensis, in order to understand the number and source of introductions throughout its current range. By quantifying genetic diversity and frequency of clonally reproduced individuals, I will also characterize how populations vary in native vs. introduced locations. More generally, my study will result in an empirical understanding of the human-mediated dispersal and establishment of an introduced species occupying coastal wetlands in the United States and Canada.

Expected Results:

Based on historical records and preliminary data, it is likely that the native range of Nematostellavectensis is along the Atlantic coast of the United States, where the species is distributed throughout a roughly continuous range from Nova Scotia to Georgia. I would expect these populations to have comparatively higher genetic diversity. I further expect to see the continuity of genetic diversity (expressed as isolation by distance) to be highest in this region. For introduced populations, I expect they will show limited diversity (as they likely derive from extreme founder events) and should prove most closely related to populations from within the source (native) range of the species. Introduced populations will likely also show higher levels of clonality than in those populations spanning the native range of the species due to possible single founder events.

Supplemental Keywords:

Nematostella vectensis, introduced species, population genetics, estuary, asexual reproduction, AFLP, salt marsh,, Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, Habitat, Environmental Monitoring, Ecology and Ecosystems, habitat dynamics, habitat use, anemone, amplified fragment length polymorphism, salt marsh, coastal species

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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