Mangrove Biogeography: The Role of Quaternary Environmental and Sea-Level Change

Mangroves and corals have broadly similar pat- terns of global distribution with a major disjunction between New World and Old World populations. However, while palaeogeographic interpretations of present coral dis- tributions have emphasized the role of environmental and sea-level fluctuations during the Quatemary, the traditional explanation of mangrove distributions has invoked gradual dispersal over the Tertiary and Quatemary from a Southeast Asian centre of origin. The distribution of mangroves at their latitudinal limits and on oceanic islands is examined. These observations together with palynological evidence for substantial changes in mangrove extent in the Holocene are used to suggest that sea-level fluctuations in particular have caused major disruptions to mangrove distributions during the Quatemary. Many species of mangroves have re- colonized oceanic islands during the Holocene and their present distribution is, at least in part, a function of their successful transoceanic dispersal to these islands. Although little evidence of Pleistocene distributions of mangroves is preserved, environmental and especially sea-level fluctuations are likely to have played a similar role in the biogeography of mangroves as they have in influencing the biogeography of corals.