Using Morphological, Molecular and Climatic Data to Delimitate Yews along the Hindu Kush-Himalaya and Adjacent Regions

Abstract

BackgroundDespite the availability of several studies to clarify taxonomic problems on the highly threatened yews of the Hindu Kush-Himalaya (HKH) and adjacent regions, the total number of species and their exact distribution ranges remains controversial. We explored the use of comprehensive sets of morphological, molecular and climatic data to clarify taxonomy and distributions of yews in this region.Methodology/Principal FindingsA total of 743 samples from 46 populations of wild yew and 47 representative herbarium specimens were analyzed. Principle component analyses on 27 morphological characters and 15 bioclimatic variables plus altitude and maximum parsimony analysis on molecular ITS and trnL-F sequences indicated the existence of three distinct species occurring in different ecological (climatic) and altitudinal gradients along the HKH and adjacent regions Taxus contorta from eastern Afghanistan to the eastern end of Central Nepal, T. wallichiana from the western end of Central Nepal to Northwest China, and the first report of the South China low to mid-elevation species T. mairei in Nepal, Bhutan, Northeast India, Myanmar and South Vietnam.Conclusion/SignificanceThe detailed sampling and combination of different data sets allowed us to identify three clearly delineated species and their precise distribution ranges in the HKH and adjacent regions, which showed no overlap or no distinct hybrid zone. This might be due to differences in the ecological (climatic) requirements of the species. The analyses further provided the selection of diagnostic morphological characters for the identification of yews occurring in the HKH and adjacent regions. Our work demonstrates that extensive sampling combined with the analysis of diverse data sets can reliably address the taxonomy of morphologically challenging plant taxa.

A multidisciplinary approach reveals hidden taxonomic diversity in the morphologically challenging Taxus wallichiana complex

“…: Fig. S4E, F) and thus represent cases of allopatric species separation by ecological adaptation as observed for other Taxus species (Poudel & al., 2012) or Rhododendron sect. Vireya H.F. Copel.…”

“…In we defined character 11 based on the insertion of the leaf on the stem. Here, as in Poudel & al. (2012), we used the leaf arrangement on branches, which is more reliable to score.…”

“…Seven characters were continuous (characters 2-7 and 25) and twenty were discrete (1, 8-24, 26, 27). Coding was performed as described in Poudel & al. (2012), ensuring consistency.…”

“…Too little material is at present available from the Philippines and Indonesia to make far-reaching taxonomic decisions. Indian material of Taxus from the Khasia hills has been morphologically and molecularly analysed by Poudel & al. (2012) and found to belong to T. mairei.…”

Distribution and preliminary conservation assessments of commonly used forest species in the Nepalese Himalayas

“…EN' (A2 a, c, d). The population of this species is decreasing at an alarming rate because of commercial demand (Liu et al, 2011;Poudel et al, 2012;Gajurel et al, 2013), and it has been listed in the CITES Appendix 2 since 1995. Fifty eight species were fairly well distributed, and were categorized as 'LC' while 14 species were placed under 'DD'.…”