Abstract
AbstractGenetic connectivity plays a crucial role in shaping the geographic structure of species. Our aim in this study was to explore the pattern of genetic connectivity in Bursa scrobilator, an iconic marine caenogastropod with long-lived pelagic larvae. Our study was based on the analysis of DNA sequence data for the 658-bp barcoding fragment of the mitochondrial cytochrome c oxidase subunit I (COI) gene. This is the largest DNA sequence dataset assembled to date for B. scrobilator. These data confirm that the two recently described subspecies B. scrobilator scrobilator (Linnaeus, 1758), from the Mediterranean and Macaronesia, and B. s. coriacea (Reeve, 1844), from West Africa, constitute two evolutionarily significant units (ESUs). We found that for the nominal subspecies, the variation in morphology (shell, radula and gross anatomy) and DNA sequences was not geographically structured, and this agrees with what we would expect in a species with high connectivity at the larval stage. The divergence between the two subspecies cannot be easily explained by isolation by distance, and we would argue that one or more extrinsic factors may have played a role in isolating the two ESUs and maintaining that isolation.
Highlights
Connectivity among populations of marine invertebrates is known to have remarkable short-to-medium term effects on genetic variability, genetic structure, range dynamics and persistence, as well as long-term effects on speciation patterns (Lowe & Allendorf, 2010; Castelin et al, 2012 and references therein)
We found that for Bursa scrobilator scrobilator genetic connectivity over long distances was high, and we found no evidence of geographic structure at both local and global spatial scales
The pattern of genetic connectivity in B. s. scrobilator is relevant for several aspects of its biology; important aspects in this respect are its taxonomic status and its capacity to respond to climate change
Summary
Connectivity among populations of marine invertebrates is known to have remarkable short-to-medium term effects on genetic variability, genetic structure, range dynamics and persistence, as well as long-term effects on speciation patterns (Lowe & Allendorf, 2010; Castelin et al, 2012 and references therein). For these reasons, connectivity is considered to be a key factor affecting the resilience of species to global change (Mawdsley et al, 2009). The adequacy of PLD as a predictor of genetic connectivity has been questioned by a few workers (e.g. Shanks, 2009); other factors such as habitat differences (Ayre et al, 2009) and past biogeographical events (Edmands, 2001; Marko, 2004) may have had a substantial impact on connectivity
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