Long‐distance dispersal or postglacial contraction? Insights into disjunction between Himalaya–Hengduan Mountains and Taiwan in a cold‐adapted herbaceous genus, Triplostegia

Abstract

Current disjunct patterns can result from long‐distance dispersal or postglacial contraction. We herein investigate the evolutionary history of Triplostegia to elucidate the disjunction between the Himalaya–Hengduan Mountain region (HHM) and Taiwan (TW). Genetic structure of Triplostegia was investigated for 48 populations using sequences from five chloroplast loci and the ribosomal nuclear internal transcribed spacer. Divergence time estimation, ancestral area reconstruction, and species distribution modeling (SDM) were employed to examine the biogeographic history of Triplostegia. Substantial genetic differentiation among populations from southwestern China (SW), Central China (CC), and TW was detected. Triplostegia was inferred to have originated in SW, and diversification began during the late Miocene; CC was colonized in the mid‐Pliocene, and TW was finally colonized in the early Pleistocene. SDM suggested an expansion of climatically suitable areas during the Last Glacial Maximum and range contraction during the Last interglacial in Triplostegia. Disjunction between HHM and TW in Triplostegia is most likely the consequence of topographic isolation and postglacial contraction. The potential climatic suitability areas for Triplostegia by 2070s (2061–2080) are predicted to slightly shrink and move northward. With continued global warming and human‐induced deforestation, extinction risk may increase for the cold‐adapted species, and appropriate strategies should be employed for ecosystem conservation.

Geographical and temporal origins of terrestrial vertebrates endemic to Taiwan

“…Similarly, high floristic similarity between Taiwan and the Eastern Himalayas has been reported before (Liao & Chen, ), and disjunctive distributions between these two regions have also been recently noted in multiple plants (e.g. Matuszak, Muellner‐Riehl, Sun, & Favre, ; Niu et al., ), supporting the Eastern Himalayas as an important source of endemic Taiwanese species.…”

“…The black branches with species names are taxa endemic to Taiwan, and the coloured branches indicate their closest relatives that were recorded in nearby regions with colours consistent with the inset map (see Supporting Information Appendix S3 for all detailed DEC results) distributions between these two regions have also been recently noted in multiple plants (e.g. Matuszak, Muellner-Riehl, Sun, & Favre, 2016;Niu et al, 2018), supporting the Eastern Himalayas as an important source of endemic Taiwanese species.…”

Phylogeographic Analyses of the East Asian Endemic Genus Prinsepia and the Role of the East Asian Monsoon System in Shaping a North-South Divergence Pattern in China

“…From the ENM analysis, we find that the suitable ranges during the LGM for P. utilis and P. scandens were larger than under current conditions and these two species may have had contact with each other during the LGM. This result is similar to some cold tolerant plants which have disjunct distributions between southwest China and Taiwan (Gao et al, 2015; Niu et al, 2017). P. scandens is found in areas of high elevation in Taiwan.…”

Geoclimatic factors influence the population genetic connectivity of Incarvillea arguta (Bignoniaceae) in the Himalaya–Hengduan Mountains biodiversity hotspot

“…This time range for the first and second crown nodes would be close to the putative abrupt intensification of the Asian monsoon regimes approximately 2.6–3.6 Ma (An et al, 2001) linked with the intense uplift of the HM (Li et al, 1995; Spicer et al, 2003; Wen et al, 2014; Favre et al, 2015). It is possible that the uplift of the eastern QTP and associated climate change induced dramatic geomorphological changes in the HHM (Favre et al, 2015; Niu et al, 2018), resulting in the change in genetic structure and geographic distribution of the I. arguta populations in the HM. This suggests that the origin and lineage differentiation are more related to the uplift of the Himalaya–Hengduan massifs, influencing the current geographical distribution and phylogeographic pattern of I. arguta .…”