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- Banag, Cecilia I., et al.
(författare)
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Ixora (Rubiaceae) on the Philippines - crossroad or cradle?
- 2017
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Ingår i: BMC Evolutionary Biology. - : Springer Science and Business Media LLC. - 1471-2148. ; 17
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Tidskriftsartikel (refereegranskat)abstract
- Background: The Philippine archipelago is globally one of the most important model island systems for studying evolutionary processes. However, most plant species on this archipelago have not yet been studied in sufficient detail. The main aim of this study is to unravel the evolutionary history and biogeographic relationships of the Philippine members of the pantropical genus Ixora. Results: The complex plastid and nuclear divergence patterns in Philippine Ixora, documented using tree and network approaches, reveal a highly dynamic evolution in Ixora, involving several phases of radiation and recolonization. Philippine Ixora comprises at least five lineages, of which one is most closely related to species from Wallacea, and the remaining four to species from Asia. Conclusions: Our study highlights the importance of Philippine species for understanding phytogeographic patterns in the Indomalayan-Australasian eco-region. The overall genetic differentiation, as well as the incongruence between genealogies based on the biparentally inherited nucleome and the maternally inherited plastome in Ixora, reflect the complex tectonic history of the Philippine archipelago. The Ixora lineage related to Wallacean species supports the delimitation of different ecozones along Huxley's line, because it is absent from Palawan. The remaining four lineages are all allied with Asian taxa, reflecting several waves of colonization. Close relationships between some widespread Philippine species and locally adapted narrow endemics suggest that the widespread, genetically diverse species act as pools for the formation of new species in a process of ongoing speciation. Our results suggest that the species concepts of some of the more widespread taxa need to be revised.
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| 2. |
- Ordas, Jorge Anton D., et al.
(författare)
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Phylogeny and the evolutionary origins of myrmecophytism in the Neonauclea clade (Rubiaceae) revisited, with particular emphasis on the Philippine lineages
- 2021
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Ingår i: Plant Systematics and Evolution. - : Springer Science and Business Media LLC. - 0378-2697 .- 1615-6110. ; 307:3
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Tidskriftsartikel (refereegranskat)abstract
- The Australasian Neonauclea is the largest genus of the tribe Naucleeae (subfamily Cinchonoideae, Rubiaceae) and is well known for its extensive radiation of myrmecophytic species. The genus is paraphyletic with respect to the genera Ludekia and Myrmeconauclea, and these three genera constitute the Neonauclea clade sensu Löfstrand et al. The Philippines is a center of species diversity of Neonauclea; however, its members have yet to be included in any molecular studies. We produced a phylogeny of the Neonauclea clade based on sequence data from nuclear (ETS and ITS) and plastid (rbcL and trnT-F) markers and including a large sampling of Neonauclea species from the Philippines. The resulting phylogeny was used to assess the phylogenetic positions and relationships of the Philippine Neonauclea species within the Neonauclea clade. We also reassessed the origins of myrmecophytism in the Neonauclea clade using ancestral state reconstructions. The sampled Philippine Neonauclea were resolved in five morphologically and geographically distinct clades. Our ancestral state reconstructions inferred a non-myrmecophytic ancestor for the Neonauclea clade, as shown by Razafimandimbison et al., and suggested at least two independent origins of myrmecophytism, one in myrmecophytic Myrmeconauclea and another in the myrmecophytic Neonauclea species from core Neonauclea. Losses of myrmedomes through multiple evolutionary reversals back to the non-myrmedome condition were inferred within core Neonauclea. Unlike the Bornean myrmecophytic lineages, our results favored a single origin of the Philippine endemic myrmecophytic Neonauclea.
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