Tropical mountains are hot spots of biodiversity and endemism, but the evolutionary origins of their unique biotas are poorly understood. In varying degrees, local and regional extinction, long-distance colonization, and local recruitment may all contribute to the exceptional character of these communities. Also, it is debated whether mountain endemics mostly originate from local lowland taxa, or from lineages that reach the mountain by long-range dispersal from cool localities elsewhere. Here we investigate the evolutionary routes to endemism by sampling an entire tropical mountain biota on the 4,095-metre-high Mount Kinabalu in Sabah, East Malaysia. We discover that most of its unique biodiversity is younger than the mountain itself (6 million years), and comprises a mix of immigrant pre-adapted lineages and descendants from local lowland ancestors, although substantial shifts from lower to higher vegetation zones in this latter group were rare. These insights could improve forecasts of the likelihood of extinction and 'evolutionary rescue' in montane biodiversity hot spots under climate change scenarios.

All parasites are thought to have evolved from free-living ancestors. However, the ancestral conditions facilitating the shift to parasitism are unclear, particularly in plants because the phylogenetic position of many parasites is unknown. This is especially true for Rafflesia, an endophytic holoparasite that produces the largest flowers in the world and has defied confident phylogenetic placement since its discovery >180 years ago. Here we present results of a phylogenetic analysis of 95 species of seed plants designed to infer the position of Rafflesia in an evolutionary context using the mitochondrial gene matR (1,806 aligned base pairs). Overall, the estimated phylogenetic tree is highly congruent with independent analyses and provides a strongly supported placement of Rafflesia with the order Malpighiales, which includes poinsettias, violets, and passionflowers. Furthermore, the phylogenetic placement of Mitrastema, another enigmatic, holoparasitic angiosperm with the order Ericales (which includes blueberries and persimmons), was obtained with these data. Although traditionally classified together, Rafflesia and Mitrastema are only distantly related, implying that their endoparasitic habits result from convergent evolution. Our results indicate that the previous significant difficulties associated with phylogenetic placement of holoparasitic plants may be overcome by using mitochondrial DNA so that a broader understanding of the origins and evolution of parasitism may emerge. P arasitic organisms have evolved independently from freeliving ancestors in most of the major lineages of prokaryotes and eukaryotes (1), but identification of the relatives of highly reduced parasites has proven to be a phylogenetic challenge in many cases (2). The evolutionary shift to an advanced parasitic lifestyle is often associated with degeneration of both morphologies and genomes, leaving few reliable characters with which to infer phylogenetic relationships (3). In angiosperms, evolutionary relationships of many hemiparasites (parasitic plants that retain the ability to photosynthesize) have recently been clarified (4), largely because they retain vegetative and floral characteristics linking them to their nonparasitic relatives and because their genomes evolve similarly to nonparasites in rate and pattern (5). In contrast, inferring the phylogenetic relationships of many holoparasitic plants (parasites that can no longer photosynthesize) has been particularly problematic because of the reduced vegetative features of holoparasites and genes that may be missing or evolve at extremely high rates under relaxed constraint (3-8). Thus, despite the fact that a comprehensive framework within which to study angiosperm phylogeny exists, provided by combined plastid and nuclear sequences from Ͼ500 species (9-11), the photosynthetic relatives of most holoparasites are currently unknown.Particularly problematic is the holoparasite Rafflesia (Rafflesiaceae), whose phylogenetic affinities have remained obscure since its description in 1...

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