Research Training Program

James Umbanhower
Carleton College
Northfield, Minnesota

M.G. Harasewych, Ph.D.
Project Advisor
Department of Invertebrate Zoology
Division of Mollusks

Genetic and Morphological Systematics of Two Western Atlantic Molluscs

This research focused on determining the phylogeny of the gastropod genus Melongena in Florida and relate this to its biogeography. Studies on the bivalve genus Donax (Adamkewicz and Harasewych, 1993 in press) were also conducted.

Randomly Amplified Polymorphic DNA (or RAPD) techniques were used as an important part of determining population structures, gene flow, and phylogeny following similar studies (Klein-Lankhorst et al., 1991; Smith et al., 1992; Hu and Quiros, 1991; and Kambhampati et al., 1992). This and other molecular techniques are powerful in evolutionary biology because they look directly at DNA and can effectively ignore environmental effects. To more completely understand the evolution of an organism, though, morphological data should be used.

Work was done on a project that began to describe the systematics of the Gastropod genus, Melongena, in Florida. The first part of the project was meant to discern morphological traits which could be used to classify the shells of several subspecies of M. corona. Photographs were taken of the shells, which were then traced using an enlarger and several points were digitized that were needed to model the shell shape. The model used had 5 parameters to model basic shell shape, and four more in describing siphonal shape. The data produced from this, and several quantative variables (# of spines on the shoulder) were input into Systat and several kinds of analyses were performed, including cluster and factor analyses. Preliminary results showed the method was feasible for differentiating between subspecies on the basis of shell morphology. This project also began to look at genetic relationships of the taxa. DNA was extracted from about 16 specimens and primers were screened for RAPD analysis. The results were unfavorable, the Melongeia DNA would not amplify with primers that had been known to amplify it before. Better purification techniques are needed. In the future, better extraction techniques will hopefully allow researchers to find the genetic relationships of the taxa and larger sample sizes of shells will give more statistically significant morphological results.

This research was supported by a grant from the National Science Foundation Research Experiences for Undergraduates (Award: BIR-9300225).