Phylogenomics, species diversification, and biogeography of Dalbergia (Leguminosae) using hybrid capture of nuclear genes
Fabien Robert Rahaingoson , Wei Gu , Oyetola Oyebanji , Shui-Yin Liu , Qin Tian , Jian Liu , Gregory W. Stull , Ryan A. Folk , Jian Wang , Douglas E. Soltis , Pamela S. Soltis , Ting-Shuang Yi , Rong Zhang
Journal of Systematics and Evolution ›› 2026, Vol. 64 ›› Issue (4) : 776 -792.
Dalbergia (Leguminosae) is a pantropical genus that serves as an ideal system for studying pantropical biogeography and diversification. However, limited taxon sampling and molecular data have hindered the resolution of intrageneric relationships and understanding of its evolutionary history. Here, we reconstruct a densely sampled phylogeny of Dalbergia based on hybrid capture of 89 low-copy nuclear loci, including 98 species spanning all major biogeographic regions and most previously recognized taxonomic clades. Phylogenetic analyses using concatenated and coalescent approaches support the monophyly of Dalbergia and consistently identify six major clades, including a distinct and newly identified Africa-Madagascar lineage (clade E) with potential taxonomic significance. Our results propose merging two of its sections, sect. Dalbergia and sect. Selenolobium, and expanding sect. Ecastaphyllum to include some African species. Topological incongruences observed between concatenated and coalescent trees, together with the high gene tree conflict at certain nodes, are consistent with localized effects of hybridization and/or incomplete lineage sorting. Divergence dating and model-based biogeographic analyses support a Neotropical origin of Dalbergia in the middle Eocene (~39 Ma), followed by repeated long-distance dispersal events from Africa to Asia, Neotropics, and Madagascar, and back into the Neotropics. An early diversification burst in Africa during the late Oligocene–early Miocene (~27–18 Ma) preceded the genus′s intercontinental expansion. Diversification rates were high across all four regions, with Madagascar showing the highest speciation rate. These macroevolutionary dynamics coincided with Eocene–Miocene climatic changes and habit shifts. This study provides a robust phylogenetic framework for Dalbergia, refines its temporal and biogeographic history, and illustrates how dispersal, climatic change, and lineage-specific diversification have interacted to generate pantropical biodiversity.
Dalbergia / Hyb-Seq / long-distance dispersal / pantropical / phylogenetic relationships / phylogenomics
2026 Institute of Botany, Chinese Academy of Sciences.
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