A leading-edge scenario in the phylogeography and evolutionary history of East Asian insular Taxus in Taiwan and the Philippines

Front Genet. 2024 May 2:15:1372309. doi: 10.3389/fgene.2024.1372309. eCollection 2024.


The cool temperate origin of gymnosperm Taxus species in East Asia is specifically diverse and widespread. Certain lineages have managed to extend their distribution further south to subtropical and tropical islands such as Taiwan and the Philippines. To address questions including whether these insular lineages, recently identified as T. phytonii, have become genetically distinct from each other and from their continental relatives, and when and how they colonized their residing islands, we sampled over 11 populations, covering 179 Taxus individuals from Taiwan and the Philippines. Using four cpDNA and one nuclear marker, we showed in population genetic and genealogical analyses that the two insular lineages were genetically distinct from each other and also from other continental Taxus and that they represented each other's closest relative. Estimated with the coalescent-based multi-type tree (MTT) analyses, we inferred an origin of Taiwanese T. phytonii more ancient than 2.49 Mya and that of Philippine T. phytonii more ancient than 1.08 Mya. In addition, the divergence demographic history revealed by both MTT and isolation with migration (IM) analyses indicated the presence of recent post-split migrations from a continental taxon, T. mairei, to Taiwanese T. phytonii, as well as from Taiwanese T. phytonii to Philippine T. phytonii. Overall, this study suggests Taiwan as a stepping stone through which the temperate-origin yew trees can extend their distributions to tropical regions such as the Philippines.

Keywords: Taxus mairei; Taxus phytonii; introgression; long-distance colonization; post-split migration; seed dispersal; yew trees.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This work was partially supported by the National Science and Technology Council, Taiwan (grant nos MOST 106-2621-B-002-002-MY2 and NSTC 111-2313-B-002-027-MY2) to C-NW. The field collection work was partly supported by the Philippine Department of Science and Technology and the Taiwan Ministry of Science and Technology (NSC100-2923-B-054-001) to VA. The Royal Botanic Garden Edinburgh (RBGE) is supported by the Scottish Government’s Rural and Environmental Science and Analytical Services Division.