Amplified fragment length polymorphism data provide a poor solution to the Littorina littorea puzzle

摘要

The status of Littorina littorea as an exotic species in North America has been debated in the biological literature for over a century. In recent decades, molecular data have been used to supplement historical and archaeological evidence that has suggested that the snail may have persisted in North America well before European settlers arrived. However, these earlier molecular studies have since been questioned due to incomplete sampling of both the geographical range of L. littorea and the genome of the species itself. Here we consider an amplified fragment length polymorphism screen of the nuclear genome, which provides a large number of independent dominant markers that can be used in resolving this historical puzzle. Although these data appear to refute earlier allozyme studies of L. littorea as indicating long-term divergence between European and American populations, the data are also problematic in that they include clear artefacts. We discuss these artefacts and suggest future approaches to definitively resolving the debate over L. littorea's introduction to North America.