I completed my MS in Zoology under the mentoring of Dr. Steve Karl at the University of South Florida in Tampa. The abstract below is from my thesis which can be found at USF's Library.

Phylogeography and Evolution of the Florida Crown Conch (Melongena corona).

Left to Right: M. corona aspinosa, M. bicolor, M. corona corona, M. corona johnstonei, M. sprucecreekensis (sizes relative to each other and nomenclature based on Clench & Turner 1956; Tucker 1994) Photos by K. Hayes

Melongena corona and closely related congeners are a conspicuous part of the marine intertidal benthic communities of Florida and southeastern Alabama. Significant genetic differentiation among adjacent populations has been conjectured based on variation in shell morphology, habitat discontinuity, low levels of adult motility, and the presence of an aplanic lecithotrophic larval stage. Furthermore, studies of the highly variable shell morphology often have resulted in confusing specific and sub-specific definitions of these gastropods, which are often referred to as the “corona complex”. Variation in shell morphology may indicate local adaptation or environmentally induced phenotypic plasticity.  In this study I utilized mitochondrial DNA sequences in order to reconstruct the phylogenetic relationships of crown conchs, and nuclear microsatellite loci to investigate the patterns of relatedness within and among populations inhabiting the southeastern United States . 

Approximately 500 individuals from 20 populations throughout the known range of the crown conch were genotyped at eight microsatellite loci. Additionally, a 1200 bp portion of the cytochrome c oxidase subunit I gene was sequenced along with a 490 bp fragment of the 16S ribosomal gene from individuals representing all known species and subspecies of the genus Melongena. Phylogenetic analyses completed with these data provide no support for current taxonomic designations within this group and these data indicate that the corona complex is composed of a single evolutionary lineage. In contrast, microsatellite data reveal population structure consistent with restricted gene flow between extant populations and phylogeography heavily influenced by historical sea-level fluctuations during the Late Pleistocene. Combined these data indicate a more recent origin for extant populations of M. corona.