| 1. |
- Merckx, Vincent S. F. T., et al.
(författare)
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Evolution of endemismon a young tropical mountain
- 2015
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 524:7565, s. 347-
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Tidskriftsartikel (refereegranskat)abstract
- Tropical mountains are hot spots of biodiversity and endemism(1-3), but the evolutionary origins of their unique biotas are poorly understood(4). In varying degrees, local and regional extinction, long-distance colonization, and local recruitment may all contribute to the exceptional character of these communities(5). 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(6). 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'(7) in montane biodiversity hot spots under climate change scenarios.
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| 2. |
- Neupane, Suman, et al.
(författare)
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The Hedyotis-Oldenlandia complex (Rubiaceae: Spermacoceae) in Asia and the Pacific : Phylogeny revisited with new generic delimitations
- 2015
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Ingår i: Taxon. - : Wiley. - 0040-0262 .- 1996-8175. ; 64:2, s. 299-322
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Tidskriftsartikel (refereegranskat)abstract
- Hedyotis and related genera (here called the Hedyotis-Oldenlandia complex) are highly debated groups in the Rubiaceae family with no consensus to date on their generic delimitations. The present study focuses on Asian-Pacific taxa from these groups and aims at resolving taxonomic inconsistencies by describing monophyletic genera within the complex. The generic circumscriptions presented in our study are based on the phylogenetic trees of nuclear (ITS, ETS) and plastid (petD, rps16) sequence data inferred using Bayesian and maximum likelihood methods. Morphological key features of the group such as habit, fruit type, seed form, and pollen type are studied and compared with the phylogeny to characterize the clades. Based on these results, the Asian-Pacific members are placed in 14 monophyletic groups across the Hedyotis-Oldenlandia complex. Of these, we accept and circumscribe 13 monophyletic genera: Debia, Dentella, Dimetia, Edrastima, Exallage, Hedyotis, Involucrella, Kadua, Kohautia, Leptopetalum, Neanotis, Oldenlandia, and Scleromitrion. Two of these, Debia and Involucrella, are here described as new genera.
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| 3. |
- Wikström, Niklas, et al.
(författare)
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Phylogeny of Hedyotis L. (Rubiaceae Spermacoceae) : Redefining a complex Asian-Pacific assemblage
- 2013
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Ingår i: Taxon. - : Wiley. - 0040-0262 .- 1996-8175. ; 62:2, s. 357-374
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Tidskriftsartikel (refereegranskat)abstract
- The genus Hedyotis (Rubiaceae: Spermacoceae) has long served as a repository for tropical herbaceous species that do not fit readily into other genera. Circumscribed broadly the genus becomes a highly heterogeneous assembly, but relationships of Hedyotis have been difficult to resolve and it has proven very difficult to circumscribe the genus in a more narrow sense. Here we present Bayesian phylogenetic analyses of Hedyotis using plastid (rps16, petD) and nuclear (ITS, ETS) sequence data to resolve monophyletic lineages, to test former taxonomic hypotheses, and to revise the taxa within a well-supported evolutionary framework. Four hundred and sixty-seven sequences representing 129 accessions, never previously included in any phylogenetic analyses, are newly reported. Hedyotis, as previously circumscribed, is polyphyletic, but all investigated species, except for Hedyotis coronaria, are resolved in one of three well-supported monophyletic groups. The largest clade includes all investigated species of Hedyotis from the Indian subcontinent as well as three groups of species with primarily Chinese distributions. The type species of Hedyotis (H. fruticosa) is resolved with the Indian subcontinent species and following previous suggestions this group is referred to as Hedyotis s.str. Species currently recognized under the generic names Metabolos and Pleiocraterium are resolved in Hedyotis s.str. The second-largest group comprises a series of smaller, but well-supported, clades including the Leptopetalum clade, the genus Kadua, an unnamed group distributed in Asia and the Pacific, and a large Asian group referred to here as the ExallagelDimetia clade. The third group includes a few SE Asian Hedyotis, as well as all investigated species of the genus Neanotis. Hedyotis coronaria is not closely related to other species from Asia and is resolved with Spern2acoce hispida. The analyses indicate that diplophragmous capsules and fruticosa-type seeds occur outside of Hedyotis s.str., and several species suggested to have these features are resolved in the ExallagelDimetia clade. Species suggested to have indehiscent capsules, a feature used by Bremekamp to characterize the genus Exallage, are also resolved in both the ExallagelDimetia clade and in Hedyotis s.str., but a close examination indicates that the capsules are not truly indehiscent in the Hedyotis s.str. species. One species of Metabolos and one species of Pleiocraterium are given new species names, and one species of Pleiocrateriam is transferred to Hedyotis and three species of Hedyotis are transferred to Neanotis.
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