Relationship of Morphology, Phylogenetics, and Biogeography in Triodopsis Rafinesque, 1819 (Stylommatophora, Polygyridae) Land Snails

Mollusks are a highly diverse phylum with some of the most extremes of body forms. The relationship between phenotype and phylogeny is studied here in two very different groups of mollusks, the bivalves and the terrestrial gastropods. The eastern oyster, Crassostrea virginica, being a nearly amorphic organism, expresses its phenotype as physiological responses to its environment. This ancient group has a huge distribution over a range of climates and conditions. The physiology of the eastern oyster is investigated to determine its response as a physiological phenotype to different tidal elevations, salinities, and environmental conditions. This research investigates the immunity gene expression and mitochondrial genes to determine if selection has any effect in the oyster response. Triodopsis snails, on the other hand, generally have small ranges that appear to be similar habitats but have many morphological forms. The morphology, biogeography and phylogenetics of the Triodopsis genus is studied to determine the status of recognized species, and probable evolutionary history. Both groups of mollusks have incredible adaptations to their respective lifestyles. The oyster and the snail are extreme examples of diversity and adaptation to adverse habitats and conditions with different life strategies.