Theses and Dissertations

Date of Award


Document Type


Degree Name

Master of Science (MS)



First Advisor

Dr. David Hicks

Second Advisor

Dr. Daniel Provenzano

Third Advisor

Dr. Erin Easton


The calanoid copepod, Acartia tonsa is one of the most abundant and well-studied estuarian species. However, the idea that this cosmopolitan species has unrestricted dispersal and high gene flow has been challenged. In this study, a more holistic picture of the phylogeography of A. tonsa was developed using the mitochondrial gene cytochrome oxidase one (mtCOI). Multiple new lineages were found in the Texas Gulf of Mexico that are basal to Northeastern Atlantic lineages. Connectivity was also observed between Brazil and the Texas Gulf of Mexico. The revised phylogeny shows a clear pattern of cryptic speciation as the species made a northward expansion since the last glacial cycle during the Pleistocene epoch. These data show that A. tonsa is a model species for observing phylogeographical structuring along the American continent.


Copyright 2017 Nicole J. Figueroa. All Rights Reserved.