Genetic differentiation within unionid mussel species.
Kody Kuehnl, PhD Student and G. Thomas Watters.

Freshwater mussels (Unionidae) are perhaps the most endangered group of aquatic organisms with more than 75 % of the recognized species considered endangered, threatened, or species of special concern. In addition, the remaining populations of these organisms are becoming increasingly more fragmented, a direct result of human impacts (i.e. habitat loss and degradation). Furthermore, much of the Unionidae remain clouded in taxonomic uncertainty, a result of the extreme environmental plasticity often found within the group combined with a lack of good morphological characters to distinguish between species. This research is focused on determining the degree of genetic differentiation among purported populations of the same species in an effort to understand the levels of structure in natural unionid populations with the purpose of developing meaningful conservation criteria/plans.

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Kody Kuehnl can be emailed at kuehnl.2 "at" osu.edu

Kody posing with a Lampsilis cardium, which has graciously given him a issue sample for genetic analysis.

Kody posing with two species of the approximately
50 species currently housed at the
Freshwater Mussel Conservation and Research Center
(Megalonaias nervosa and Tritigonia verrucosa)

1) An Intraspecific phylogeographic analysis of the rainbow mussel, Villosa iris (Bivalvia: Unionidae)

The rainbow mussel shows variation in several conchological features throughout its range. The question becomes: Are these variants the same species, a result of environmental plasticity, or will molecular techniques reveal the presence of unique species? Preliminary results using mitochondrial DNA (mtDNA) have illustrated that these conchological variants are likely not the same species, and moreover, in some instances, do not belong in the genus Villosa.

2) A phylogenetic analysis of the genus Villosa using the mtDNA F and M mitotypes.

The genus Villosa, as it is currently classified, is incongruent with current genetic analyses. As a result, we have been using mitochondrial DNA markers to conduct a phylogenetic analysis of all the nominal taxa in the genus Villosa as well as the genus Lampsilis (sister taxa). Unionids are unique in that the transmission of mtDNA is bi-parental. Therefore, two unique mtDNA sequences (male and female) can be used to clarify taxonomic uncertainties within the group.

(for more information on this species and the entire Villosa group go to the Virtual Villosa page).

3) Characteriztion of in-stream population structure of the

mucket, Actinonaias ligamentina, using microsatellites.

Currently a paucity of information exists on the general population structure of mussels at a fine scale. Using highly variable microsatellite DNA markers, we hope to understand the relationship/kinship of in-stream populations, current effective population sizes, patterns of dispersal and migration, and habitat characteristics responsible for good recruitment and survival.

4) Augmentation and reintroduction of the endangered clubshell (Pleurobema clava) and northern riffleshell (Epioblasma t. rangiana) in Illinois and Ohio.

A handful of the federally endangered mussel Pleurobema clava.

(This page last updated Jan 2007)