DNA Extraction of Halophila stipulacea Plants for Genetic Variability around the Virgin 
Islands 
 
Shantae Lewis, Undergraduate Student, University of the Virgin Islands College of Math and 
Science 
Sojourna Ferguson, Undergraduate Student, University of the Virgin Islands College of Math 
and Science 
Alice M. Stanford, Ph.D., Staff, University of the Virgin Islands College of Math and Science 
 
  
Invasive species, such as the seagrass Halophila stipulacea, pose a threat to the ecosystems that 
they invade by outcompeting native species for resources. The goal of this project is to determine 
the genetic variability of H. stipulacea and to use that information to help create an invasion 
history model. In order to achieve this goal, we used the 2bRAD method to identify single 
nucleotide polymorphisms (SNPs), and analyzed genetic structure and clonal diversity. 
Approximately 8 samples were analyzed from Magen’s, John Brewers, and Lindbergh bay on St. 
Thomas. From this, we noted 3 different genotypes. Samples collected from John Brewers and a 
Magen’s Bay sample were clones, while the Lindbergh and 2nd Magen’s Bay samples differed 
from all other samples. We found the richness of diversity (R) to be 0.28571 over 4 loci. Since 
this species is known to reproduce clonally outside of its native habitat, this implies that multiple 
invasions have occurred throughout the Virgin Islands. Currently, we are assessing genetic 
diversity of 56 additional samples from different bays around St. Thomas, Water Island and St. 
John, and in the future, we will determine whether environmental factors such as depth are 
associated with particular clones in Brewers Bay. 
 
Keywords: Halophila stipulacea, invasive species, genetic diversity