Genetic structure of Brachidontes puniceus populations in Cape Verde archipelago shows signature of expansion during the last glacial maximum

Abstract

Quaternary climatic fluctuations had major impacts on species’ distributions over the last 2.5 Myr. Expansions and contractions of the polar ice caps throughout glacial cycles strongly affected terrestrial fauna and flora whereas eustatic sea level variations had major consequences on rocky-shore communities. The effect of these glacial episodes on marine organisms inhabiting oceanic islands is still poorly understood. We analysed the genetic structure of the marine mussel Brachidontes puniceus from the Cape Verde Islands using mitochondrial sequence data. The apparent absence of physical oceanographic barriers or ecological filters in the geographical range of B. puniceus is reflected in the lack of genetic structure found among populations from the entire archipelago. Larval dispersal in B. puniceus likely played a critical role in the demographic connectivity of populations across the Cape Verde archipelago. Results from demographic analysis were consistent with a population expansion promoted by an increase in the habitat available for larval settlement resulting from a low sea-level stand during the last glacial maximum.