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- Title
Plastid phylogenomics clarifies broad-level relationships in Bulbophyllum (Orchidaceae) and provides insights into range evolution of Australasian section Adelopetalum.
- Authors
Simpson, Lalita; Clements, Mark A.; Orel, Harvey K.; Crayn, Darren M.; Nargar, Katharina
- Abstract
The hyperdiverse orchid genus Bulbophyllum is the second largest genus of flowering plants and exhibits a pantropical distribution with a center of diversity in tropical Asia. The only Bulbophyllum section with a center of diversity inAustralasia is sect. Adelopetalum. However, the phylogenetic placement, interspecific relationships, and spatio-temporal evolution of this section remain largely unclear. To infer broad-level relationships within Bulbophyllum, and interspecific relationshipswithinsect. Adelopetalum, a genome skimmingdatasetwasgenerated for 89 samples, which yielded 70 plastid coding regions and a nuclear ribosomal DNA cistron. For 18 additional samples, Sanger data fromtwo plastid loci (matK and ycf1) and nuclear ITSwere added using a supermatrix approach. The study provided newinsights into broad-level relationships in Bulbophyllum, including phylogenetic evidence for the non-monophyly of sections Beccariana, Brachyantha, Brachypus, Cirrhopetaloides, Cirrhopetalum, Desmosanthes, Minutissima, Oxysepala, Polymeres, and Sestochilos. Section Adelopetalum and sect. Minutissima s.s. formed a highly supported clade that was resolved as a sister group to the remainder of the genus. Divergence time estimations based on a relaxed molecular clock model placed the origin of Bulbophyllum in the Early Oligocene (ca. 33.2 Ma) and sect. Adelopetalumin the Late Oligocene (ca. 23.6 Ma). Ancestral range estimations based on a BAYAREALIKE model identified the Australian continent as the ancestral area of the sect. Adelopetalum. The section underwent crown diversification fromthemid-Miocene to the late Pleistocene, predominantly in continental Australia. At least two independent long-distance dispersal events were inferred eastward from the Australian continent to New Zealand and to New Caledonia from the early Pliocene onwards, likely mediated by predominantly westerly winds of the Southern hemisphere. Retraction and fragmentation of the eastern Australian rainforests from the early Miocene onwards are likely drivers of lineage divergence within sect. Adelopetalum facilitating allopatric speciation.
- Subjects
AUSTRALASIA; NEW Caledonia; WESTERLIES; VICARIANCE; SPATIOTEMPORAL processes; TIME perception; FLOWER shows; ORCHIDS; PHYLOGEOGRAPHY; MOLECULAR clock
- Publication
Frontiers in Plant Science, 2024, p1
- ISSN
1664-462X
- Publication type
Article
- DOI
10.3389/fpls.2023.1219354