Deep Intraspecific Divergence in the Endemic Herb Lancea tibetica (Mazaceae) Distributed Over the Qinghai-Tibetan Plateau

Abstract

Qinghai-Tibetan Plateau (QTP) is an important biodiversity hub, which is very sensitive to climate change. Here in this study, we investigated genetic diversity and past population dynamics of Lancea tibetica (Mazaceae), an endemic herb to QTP and adjacent highlands. We sequenced chloroplast and nuclear ribosomal DNA fragments for 429 individuals, collected from 29 localities, covering their major distribution range at the QTP. A total of 19 chloroplast haplotypes and 13 nuclear genotypes in two well-differentiated lineages, corresponding to populations into two groups isolated by Tanggula and Bayangela Mountains. Meanwhile, significant phylogeographical structure was detected among sampling range of L. tibetica, and 61.50% of genetic variations was partitioned between groups. Gene flow across the whole region appears to be restricted by high mountains, suggesting a significant role of geography in the genetic differences between the two groups. Divergence time between the two lineages dated to 8.63 million years ago, which corresponded to the uplifting of QTP during the late Miocene and Pliocene. Ecological differences were found between both the lineages represent species-specific characteristics, sufficient to keep the lineages separated to a high degree. The simulated distribution from the last interglacial period to the current period showed that the distribution of L. tibetica experienced shrinkage and expansion. Climate changes during the Pleistocene glacial-interglacial cycles had a dramatic effect on L. tibetica distribution ranges. Multiple refugia of L. tibetica might have remained during the species history, to south of the Tanggula and north of Bayangela Mountains, both appeared as topological barrier and contributed to restricting gene flow between the two lineages. Together, geographic isolation and climatic factors have played a fundamental role in promoting diversification and evolution of L. tibetica.

The East Asian Winter Monsoon Acts as a Major Selective Factor in the Intraspecific Differentiation of Drought-Tolerant Nitraria tangutorum in Northwest China

“…The sampled populations clustered into three distinct lineages, designated as West, East-A, and East-B lineages, based on the construction of a phylogenetic network and PhyML tree (Figures 2A and 4). Notably, the haplotypes predominantly located in western and eastern regions were found to be separated into the so-called West and East lineages, respectively (Figure 2B), suggesting that molecular variance among populations is conserved and regional, as has been recently reported for several alpine species, such as Lancea tibetica, Panzerina lanata, and Corydalis hendersonii [6,15,39]. It is worth noting that the H31 haplotype, as a recent common ancestral haplotype, was first differentiated from the outgroup lineage with high bootstrap values, while its adjacent H11 haplotype was shared with both East-A and East-B lineages (Figures 2A and 3).…”

“…It is widely believed that the range of a large proportion of alpine species contracted under glacial oscillations, and that this phenomenon accelerated the process of genetic divergence. This premise has been documented in many species of plants [ 16 , 19 , 39 , 48 , 49 ] and animals [ 50 , 51 , 52 ]. Two bioclimate factors, ‘precipitation’ and ‘temperature’, were greatly reduced during the LGM [ 53 ], and have been identified as the major factors determining suitable distribution ranges for N. tangutorum ( Supplementary Table S4 ).…”

Phylogeography of Bellamya (Mollusca: Gastropoda: Viviparidae) snails on different continents: contrasting patterns of diversification in China and East Africa

“…However, the uprising of the Himalayan Mountain [54] and consequential climatic changes in the region started to impede species exchange during the Pleistocene, when the climate became much drier and cooler [69, 70]. This had caused a retreat of rainforest cover which was replaced by savannahs and deserts in Southeast Asia [57].…”

Genetic diversity, phylogeography, and maternal origin of yak (Bos grunniens)

“…Studies on Juniperus przewalskii [ 47 ], Metagentiana striata [ 48 ], and Pedicularis longiflora [ 49 ] indicated that some species may have retreated to refuges on the edge of the QTP during the glacial epoch and recolonized the plateau and adjacent highlands at the end of epoch. In addition, some glacial refugia on the QTP supported the survival of plant species, such as Hippophae rhamnoides [ 50 ] and Spiraea alpina [ 51 ], during climate change [ 1 , 52 ]. Research on Aconitum gymnandrum [ 53 ], Hippophae tibetana [ 54 ], Rhodiola alsia [ 55 ], and Rhodiola chrysanthemifolia [ 56 ] has shown that there were several miniature refugia on the QTP.…”

“…The Qinghai-Tibet Plateau (QTP), one of the largest and youngest plateaus in the world, was formed around 40 million years ago (Ma) following the collision of the Indian tectonic plate with the Asian plate through several uplift events [ 1 ]. A large number of endemic species have appeared in the QTP and adjacent areas [ 2 ], due to its unique ecological environment.…”