Graduate student W. R. Hoeh proposes to study the taxonomic distribution of various reproductive strategies, especially simultaneous hermaphroditism, in the freshwater clam genus Anodonta. Preliminary investigations using enzyme electrophoresis have shown notable variation in levels of self- vs. cross-fertilization, and this class of data will be used to identify "breeding system". Restriction fragment patterns of mitochondrial DNA will be used to establish evolutionary relationships among regional species and subspecies. The distribution of the various reproductive strategies will be studied by superimposing electrophoretic and morphological data from histological sections of reproductive tissue onto the evolutionary tree. This treatment will reveal the number of times and the circumstances under which hermaphroditism has appeared in the group. The proposed research has implications beyond the immediate area of specialization. It will lead to a better understanding of the evolutionary history of the genus, and of the evolutionary origins and significance of different reproductive strategies.
