A late Pleistocene marine glacial refugium in the south-west of Hainan Island, China: Phylogeographical insights from the brown alga Sargassum polycystum

Aim: Hainan Island, southern China, is characterized by rich diversity and endemism of marine organisms, yet the underpinning mechanisms and processes contributing to speciation and diversification are poorly understood. Here, the brown alga Sargassum polycystum is used as a model to identify putative marine glacial refugia and explore biogeographical patterns driven by climate change in the late Pleistocene ice ages.
Location: South-East Asia.
Methods: Mitochondrial cox1 and cox3 and nuclear internal transcribed spacer-2 (ITS2) were obtained from 310, 325 and 313 individuals of S. polycystum (23 localities), respectively. Phylogenetic trees (maximum likelihood and Bayesian inference) and haplotype/ribotype networks were constructed to elucidate phylogeographical patterns. Analysis of molecular variance (AMOVA), neutrality tests (Tajima's D and Fu & Li's D*), current (θπ) and historical (θw) genetic diversities and extended Bayesian skyline plots (EBSP) were used to estimate histo...