Evaluation of a potentially highly restricted freshwater gastropod species: Implications for conservation

Background/Question/Methods

Mollusks are the second most diverse animal phylum on the planet in terms of number of described species and nonmarine mollusks are among the most imperiled groups of invertebrate taxa. In particular, freshwater and terrestrial mollusks have the highest number of documented extinctions of any major taxonomic group. Such extinctions are not without their consequences as nonmarine mollusks provide several ecosystem functions including the regulation rates of primary production, decomposition, water clarity, and nutrient cycling. Given this and the level of fluidity within freshwater mollusk taxonomy, the proper identification of potentially endangered species is an issue of high concern. The purpose of this study is to evaluate the species status of a small freshwater snail endemic to southeastern Oregon within the Owyhee River, referred to as the Owyhee wet-rock physa. Analysis using standard molecular, anatomical, and morphological approaches will be employed using specimens from both a putative sister species and another species with similar morphology and habitat conditions as the Owyhee wet-rock physa. In addition, I will visit the location where samples of the Owyhee wet-rock physa were previously observed and determine population densities using quadrats, document characteristics of its habitat and map its overall distribution within this region.

Results/Conclusions

Preliminary observations and molecular work suggest that the Owyhee wet-rock physa is a distinct species. The Owyhee wet-rock physa is geographically isolated within the Owyhee River and is found approximately 400 miles away from the morphologically similar physa species which inhabits a very similar environment, suggesting convergent evolution. Furthermore, when analyzed using both COI and 16S gene regions, twelve individuals from the Owyhee river location produced gene trees where all individuals grouped together and distinct from all other sequences of physids that are available in GenBank, including the putative sister species. Due to the current atmosphere of taxonomic disarray within freshwater mollusks, the evaluation of this putative species will advance our understanding of patterns of biodiversity of these taxa and provide a proper evaluation of their conservation needs.