A map-based approach to assessing genetic diversity, structure, and connectivity in the seagrass Halodule wrightii

Seagrass cover has declined in many areas of the world in a trend that has accelerated over the past several decades. This raises concern for both the impact the decline in cover has on coastal ecosystems and the effect it may have on seagrass evolutionary potential, as genotypic and genomic variation is lost. We used 8 microsatellite loci to investigate genetic diversity, structure, and connectivity in the seagrass Halodule wrightii from the Gulf of Mexico (Texas, USA) and western Atlantic (Bermuda). We examined how estimates correlated with changes in H. wrightii abundance and distribution on the Texas Gulf coast over the past 50 yr. Results show that, compared to other species, H. wrightii from this region exhibits variable clonal diversity (R = 0.02-0.81), moderate allelic diversity (mean AR = 4.09), and relatively high heterozygosity (mean He = 0.56). The patterns of genetic diversity and structure, however, do not entirely coincide with either geography or recent historical trends...