Bivalve ligament - a new source of DNA for historical studies

Abstract

Bivalves are aquatic animals enclosed in 2 rigid shells that are held together by a hinge ligament. Features of the shell valves are important in taxonomy, and museums hold global collections of catalogued fossil, historical and contemporary specimens. Museum collections of plants and animals are routinely used for the retrieval of DNA, but to date this has not been extended to bivalves. We show that DNA can be extracted from the ligament of the bivalve shell. The use of this tissue for DNA extraction allows for the non-destructive sampling of archived specimens, as once a portion of the ligament has been removed, the remaining shell plus shell ligament scar, essential features in classical taxonomic identification, are left intact. We extracted DNA from the ligament of individual mussel shells collected in 1970, and compared population genetic structure using a nuclear DNA marker with a sample of recent (2006) shells from the same location. We present a new source of genetic data that can be used to expand many areas of bivalve taxonomy, population history and phylogeography.