Research Description:

Genetic Evaluation of Species Distinctions in Conservation of Endangered 'Species'

The ability to make accurate species distinctions has become increasingly important in regard to determining whether or not a species should be classified as "endangered." Genetic evaluations of historical species distinctions are sometimes necessary to clarify boundaries. This is true in the case of the endangered Stock Island Tree Snail (Orthalicus reses reses) and the Keys Tree Snail (Orthalicus reses nesodryas).

Determination of how closely related these large arboreal snails are to each other will be of great value to the South Florida Ecosystems Threatened/Endangered Species Recovery Program. They are currently classified as subspecies of the same species, but there is some evidence to suggest that they represent two distinct species. Pilsbry (1946) and Fred S. Thompson (Curator of Malacology at the Florida Museum of Natural History, personal communication) believe that the two 'subspecies' of Orthalicus reses do not interbreed due to differences in their anatomy. It is clear from all accounts by malacologists and other amateur snail collectors that Stock Island snails do not breed with the Keys Tree Snail where presently in contact. Likewise, neither of the reses taxa appear to interbreed with Orthalicus floridensis, the Florida Tree Snail. Definitive taxonomic and genetic evaluations of the three taxa have not been done to date.

I am working in the BEECS genetic analysis lab to try and determine just how different or similar these organisms are. The DNA that codes for the 16S ribosomal subunit is often sequenced and compared as one way of determining relatedness. I have completed this sequencing, and found that all three are nearly identical. Further work was obviously needed, and I am now using an Amplified Fragment Length Polymorphism (AFLP) technique to try and measure genetic differences between individuals and perhaps get some idea of the amount of gene flow between populations, or even subspecies.