Identification of 'extinct' freshwater mussel species using DNA barcoding

Area of Science:

• Conservation Biology
• Freshwater Ecology
• Molecular Systematics

Background:

• Freshwater mollusks face severe threats, with 70% of North American species imperiled.
• Human impacts on the Coosa River have likely caused numerous mollusk extinctions, but species boundaries are uncertain.

Purpose of the Study:

• To reassess the extinction status of freshwater mussels in the Coosa River basin.
• To clarify species-level taxonomy within the genus Pleurobema using molecular data.

Main Methods:

• Extensive freshwater mussel surveys in the upper Coosa River basin.
• DNA barcoding and molecular phylogenetic analyses of collected specimens.
• Morphological examination of rediscovered species.

Main Results:

• Rediscovery of four morphospecies of Pleurobema mussels previously believed extinct in the upper Coosa basin.
• Molecular data indicate at least three distinct species: Pleurobema decisum, P. hanleyianum, and P. stabile.
• Identification of a fifth 'extinct' form in an adjacent basin and higher-than-recognized endemism.

Conclusions:

• The study confirms the rediscovery of several 'extinct' Pleurobema species in the Coosa River.
• Molecular evidence supports at least three distinct species, indicating significant unrecognized endemism.
• Urgent conservation actions are crucial to protect these rediscovered taxa and their ecosystem.