Genetic structure of Halodule wrightii populations from the laguna madre region in the western Gulf of Mexico

Abstract

A random amplified polymorphic DNA assay was used to assess genetic variation in populations of the seagrass Halodule wrightii (Ascherson) from the western Gulf of Mexico. This region includes one of the world's few hypersaline lagoons (Laguna Madre) and contains the vast majority of seagrasses on the Texas coast. Results indicate a moderate amount of genetic diversity among populations. The highest level (He = 0.33) was found in a population from Nueces Bay, a disturbed site in the Coastal Bend area, whereas the lowest was found in a Lower Laguna Madre population (He 0.15). Genetic differentiation generally followed an isolation-by-distance model. The Nueces Bay population also showed the greatest degree of differentiation, whereas the Redfish Bay and Lower Laguna Madre populations were relatively similar (ΦST = 0.091 ). Combined with previous results, we now have a rudimentary picture of genetic variation in this species from the Texas Gulf Coast.© 2008 by the Marine Environmental Sciences Consortium of Alabama.