Contrasting demographic patterns of Ceriops tagal (Rhizophoraceae) populations in the South China Sea

Demographic history and dispersal ability are significant factors in determining the genetic composition of a population. In this study, we examined the phylogeographic patterns of Ceriops tagal from the Hainan Island and the Gulf of Thailand in the South China Sea, where there are abundant mangrove species. Nucleotide variations in two chloroplast DNA spacers were compared with trace Ceriops propagule dispersal routes and demographic history. An analysis of Templeton, Crandall and Sing's (TCS) parsimonious networks and population demographics suggests that the Ceriops population gradually expanded from the northern parts of the South China Sea to the south-western populations in the Gulf of Thailand. Such phylogeographic inferences reflect a postglacial southward shift in the mangrove genetic diversity centre and a connection between the demographic dynamics and the coastal range expansion caused by the sea-level rise in the Pleistocene. Therefore, the phylogeographic pattern and historical demography of mangrove species were affected by glaciations during the Pleistocene such as temperate biota.