Report on Molecular Systematics of Poorly-Known Freshwater Mollusks of Alabama Dr. David Campbell, Dr. Phil Harris University of Alabama, Biodiversity and Systematics, Box 870345, Tuscaloosa AL 35487-0345 Project Summary This project used molecular sequence data to investigate several Priority 1 and 2 species of freshwater mollusks. Main questions Is there significant genetic variation in Elliptio arca across the Mobile basin? Is Elliptio purpurella present in Alabama and genetically distinct from other Elliptio species? How different is Elliptio mcmichaeli from E. crassidens? What are the relationships of Fusconaia escambia? Are there significant differences between Coosa and Tennessee populations assigned to Lasmigona holstonia? Are there significant differences between middle and upper Coosa populations of Strophitus connasaugaensis? Does the species occur in the Black Warrior or Tombigbee? Is Toxolasma corvunculus different from T. parvus? Is Toxolasma cylindrellus different from T. lividus? Are there additional species of Toxolasma in the Escambia, Yellow, and Choctawhatchee systems? How are they related to the ACF and Mobile species? Are the priority species of Elimia in the Cahaba system truly distinct species or merely ecomorphs? Are the priority species of Pleurocera in the Tennessee system truly distinct species or merely ecomorphs? Results In addition to the specific target species (indicated in bold), some related priority 1 and 2 species were analyzed for comparison. Results for priority 1 and 2 species are as follows: Elliptio arca: No significant genetic variation was detected between populations from different parts of the Mobile basin. Moderate genetic distance from other Elliptio species suggests its biological requirements might also be somewhat different, requiring corresponding design of conservation techniques. Elliptio arctata: Moderate genetic distance from other Elliptio species suggests its biological requirements might also be somewhat different, requiring corresponding design of conservation techniques. Elliptio dilatata: High genetic distance from other Elliptio species suggests its biological requirements are different, requiring corresponding design of conservation techniques. Elliptio mcmichaeli: Slight genetic distance from E. crassidens. Biological requirements are probably very similar to that species. Elliptio purpurella: Not clearly distinguished from the icterina/complanata group of species, due to both limited genetic divergence and the difficulty of confidently identifying reference specimens. This group is present in the Tallapoosa system, though previously it was not known in the Mobile basin. Fusconaia barnesiana: High genetic distance from other Fusconaia species suggests its biological requirements are different, requiring corresponding design of conservation techniques. Fusconaia cor: Closely related to F. cuneolus but distinct. They place within Fusconaia and probably have similar biological requirements to the more common F. cerina. Fusconaia cuneolus: Closely related to F. cor but distinct. They place within Fusconaia and probably have similar biological requirements to the more common F. cerina. Fusconaia escambia: Closely related to Quincuncina burkei but distinct. They place within Fusconaia and probably have similar biological requirements to the more common F. cerina. Fusconaia rotulata: Closely related to the more common F. ebena. However, these two species are very distantly related to other Fusconaia species and probably have rather different biological requirements. Fusconaia subrotunda: Places within Fusconaia and probably has similar biological requirements to the more common F. cerina. Lasmigona costata: Very different from some of the other species currently assigned to Lasmigona. Lasmigona holstonia: At least three different evolutionary units are currently placed under this name. In Alabama, the upper Coosa and upper Tennessee forms appear different; a third form only occurs in Tennessee. None are close relatives of L. costata. Strophitus connasaugaensis: Closely related to but distinct from S. subvexus. The upper Coosa form (not currently known to live in Alabama) and the mid-Coosa form show a moderate level of genetic difference and probably require separate conservation. These species are not closely related to S. undulatus and probably have very different biological requirements. Sampled specimens from the Tombigbee and Black Warrior were S. subvexus, not S. connasaugaensis. Strophitus undulatus: Not very closely related to any of the other sampled species. Toxolasma corvunculus: Is a valid species, but shells may be confused with the common T. parvus in the Black Warrior and Tombigbee systems. Toxolasma cylindrellus: Is a valid species, most closely related to T. lividus. Gulf drainage Toxolasma species: Three overlooked evolutionary units exist: the Escambia and Pea form, the Choctawhatchee form, and a second species (along with T. paulus) in the ACF system. Elimia ampla: Not clearly different from E. variata. The sampled Elimia species fell into several groups that were relatively distantly related to each other, suggesting that there may also be differences in their biological requirements. Elimia annettae: Identification may be a problem, as two specimens appeared closely related to E. bullula from the Coosa but the third was quite different. Elimia bellacrenata: Relatively close to two of the E. annettae and to E. bullula, but may be a distinct species. Similar specimens observed in Spring Creek upstream from Montevallo suggest that the species may be more widespread in the upper Little Cahaba system than currently thought. Elimia cochliaris: Genetically very distinctive. A second population from Buck Creek may be sufficiently genetically different to need separate conservation management. Elimia varians: Identification seems to be a problem, as three specimens all came out quite different from each other. Elimia variata: Not clearly different from E. ampla. Pleurocera alveare: Seems to fall genetically within the range of variation of P. canaliculata. Pleurocera pyrenella: Seems to fall genetically within the range of variation of P. canaliculata. Conservation implications Species with high levels of genetic difference between populations, especially from different drainages, should probably be treated as separate entities for conservation. This will probably raise the conservation priority for those species. Further study of genetically distinctive populations is needed to look for mrophological differences that can be used in the field in conservation work. Different species with low genetic difference between them may be simply ecomorphs, not requiring separate conservation. Current genus names are not always a reliable guide to the needs of rare species. Report on Molecular Systematics of Poorly-Known Freshwater Mollusks of Alabama Dr. David Campbell, Dr. Phil Harris University of Alabama, Biodiversity and Systematics, Box 870345, Tuscaloosa AL 35487-0345 Abstract: The conservation status of several species of freshwater mollusks in Alabama has been unclear due to uncertainties about their systematics and identification. This project investigated several problematic taxa using DNA sequencing to provide new evidence on their taxonomic status. In turn, these data provide information that suggests revisions in the conservation status of several taxa. In general, the unionids have more evolutionarily significant forms than currently recognized, whereas some of the pleurocerids may be oversplit. Many species reported to range across multiple river systems actually constitute multiple evolutionary units. Introduction Alabama has one of the most diverse freshwater mollusk faunas in the world, with over 350 species. Many species are highly sensitive to human-caused habitat modification such as impoundment and siltation. As a result, a large proportion of the priority 1 and 2 species in Alabama are freshwater mollusks. However, the classification and identification of species is problematic due to high individual variation, similarities between species, and lack of modern taxonomic review. Both unionids and pleurocerids are large and slow-moving, though the mussels have high dispersal potential as larvae parasitic on fish. Neither group can readily cross divides between river systems. This produces high potential for geographic isolation. As a result, similar forms in different river systems may actually be reproductively isolated species and deserve careful scrutiny. On the other hand, some freshwater mollusks show significant ecophenotypic variation within species. Because of this, some workers treat numerous named forms as merely variants of a single species. An extreme example is Hannibal (1912), who lumped almost the entire genus Elimia into a single species. The uncertainty regarding the pleurocerid snails is so high that no one has attempted to thoroughly revise them since Goodrich (1940, 1941a,b). Unfortunately, he did not explain most of his decisions, and some of his reasoning does not agree with modern practice or current understanding of systematics and evolution. Also, molecular data suggest that the current genus-level classification of freshwater mollusks requires extensive revision (Lydeard et al., 2000; Minton et al., 2003; Campbell et al., 2005). This affects conservation because the biological requirements of poorly-known rare species often must be inferred from better-known related species.