Long-Distance Dispersal after the Last Glacial Maximum (LGM) Led to the Disjunctive Distribution of Pedicularis kansuensis (Orobanchaceae) between the Qinghai-Tibetan Plateau and Tianshan Region

Abstract

Quaternary climate fluctuations have profoundly affected the current distribution patterns and genetic structures of many plant and animal species in the Qinghai-Tibetan Plateau (QTP) and adjacent mountain ranges, e.g. Tianshan (TSR), Altay, etc. In this greater area disjunct distributions are prominent but have nevertheless received little attention with respect to the historical processes involved. Here, we focus on Pedicularis kansuensis to test whether the current QTP and TSR disjunction is the result of a recent Holocene range expansion involving dispersal across arid land bridge(s) or a Pleistocene range fragmentation involving persistence in refugia. Two chloroplast DNA spacers were sequenced for 319 individuals from 34 populations covering the entire distribution range of this species in China. We found a total of 17 haplotypes of which all occurred in the QTP, and only five in the TSR. Overall genetic diversity was high (HT = 0.882, HS = 0.559) and higher in the QTP than in the TSR. Genetic differentiation among regions and populations was relatively low (GST = 0.366) and little evidence for a phylogeographic pattern emerged. The divergence times for the four main lineages could be dated to the early Pleistocene. Surprisingly, the two ubiquitous haplotypes diverged just before or around the Last Glacial Maximum (LGM) and were found in different phylogenetic lineages. The Species Distribution Model suggested a disappearance of P. kansuensis from the TSR during the LGM in contrast to a relatively constant potential distribution in the QTP. We conclude that P. kansuensis colonized the TSR after the LGM. The improbable long-distance dispersal by wind or water across arid land seed flow may well have had birds or men as vector.

Population Genetic Differentiation and Taxonomy of Three Closely Related Species of Saxifraga (Saxifragaceae) from Southern Tibet and the Hengduan Mountains

“…However, in the present case we would have expected any hybrid signature to be detected in the zone of contact between the two lineages (Wang et al, 2001 ; Yang et al, 2012 ), but the two populations involved, BM and CM, are the furthest apart in the study, separated by some 1,200 km, rendering hybridization an unlikely explanation. Nevertheless, we cannot completely reject the possibility of long distance pollen-mediated gene flow (Li et al, 2016 ), especially if it has involved intervening populations that were not sampled by us. Molecular clock analysis of the ITS dataset suggests that the two genotypes, G2 and G3, have only relatively recently diverged from their nearest relatives: 0.10 Ma (node f, 95% HPD = 0–0.42 Ma) and 3.09 Ma (node i, 95% HPD = 1.47–5.46 Ma), respectively.…”

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

“…Compared with North America and northern Europe, East Asia was inferred to be less affected by glaciation except in the higher mountains (Pinot et al., 1999; Shi & Yao, 2002). Numerous species show disjunct distributions in the high mountains of East Asia (Li et al., 2016; Liu et al., 2014; Meng et al., 2017; Wang, 1989; Wang et al., 2013). In particular, disjunctions between the Himalaya–Hengduan Mountain region (HHM) and Taiwan (TW) have received extensive attention because of the geographically distant separation of the two regions by the Taiwan Strait and a terrestrial distance of over 2,000 km (Chen, Ying, & Lu, 2012; Wu & Wang, 2001; Ye, Chen, Liu, Qin, & Yang, 2012).…”

Phylogeography and conservation genetics of the endangered Tugarinovia mongolica (Asteraceae) from Inner Mongolia, Northwest China

“…mongolica . Several causes of this divergence could be: habitat fragmentation resulting from periodic oscillations of the Quaternary climate [50–52], lack of long distance dispersal [53], and geographic isolation [1, 4, 54, 55].…”