Global distribution and genetic discontinuities of mangroves - emerging patterns in the evolution of Rhizophora

Duke, Norman; Lo, Eugenia; Sun, Mei

Mangroves are often described as a group of plants with common features and common origins based mostly on their broad distributional patterns, together with an erroneous view of comparable abilities in long distance dispersal. However, whilst mangroves have common needs to adapt to rigorous environmental constraints associated with regular seawater inundation, individual taxa have developed different strategies and characterisitics. Since mangroves are a genetically diverse group of mostly flowering plants, they may also have evolved at quite different geological periods, dispersed at different rates from different locations and developed different adaptive strategies. Current distributions of individual taxa show numerous instances of unusual extant distribution which demonstrate finite dispersal limitations, expecially across open water. Our preliminary assessment of broad distribution and discontinuities reveal important patterns. Discontinuities, in the absence of current disperal barriers, may be explained by persistent past barriers. As we learn more about disontinuities, we are beginning to appreciate their immense implications and what they might tell us about past geological conditions and how these might have influenced the ditribution and evolution of mangroves. In this article we describe emerging patterns in genetic relationships and distributions based on both current knowledge and preliminary results of our studies of molecular and morphometric characteristics of Rhizophora species in the Indo West Pacific region.

Global distribution and genetic discontinuities of mangroves - emerging patterns in the evolution of Rhizophora

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