Chloroplast phylogeography of Helianthemum songaricum (Cistaceae) from northwestern China: implications for preservation of genetic diversity

Abstract

Two chloroplast intergenic spacers (trnD-trnT and rps16-trnK) were used to study the phylogeographical structure of Helianthemum songaricum in northwestern China, with 12 haplotypes detected. Phylogenetic analysis showed that H. songaricum comprised two lineages, one distributed in the Yili Valley and the other in the western Ordos Plateau. Nested clade phylogeographic analysis likewise indicated that haplotypes in the Yili Valley and those in the western Ordos Plateau formed sister monophyletic clades. This lineage split was also supported by AM-OVA analysis and the Mantel test. AMOVA showed that 99.41% of variance in H. songaricum occurred between the two distribution regions, and correlation between genetic differentiation and geographical distances was significant (r 2 = 0.877, P \ 0.0001). All populations in the Yili Valley shared haplotype A with high frequency, and range expansion was detected by nested clade analysis and strongly supported by negative Fu's F S -values, Tajima's D-values, and mismatch distribution analysis. We speculate that aggravation of the dry and cold climate during the early Quaternary, combined with plant physiological features, were determining factors contributing to the lineage split, and climate oscillations most likely led to the Yili range expansion. The high drift load (F ST = 0.9923, G ST = 0.663) and inbreeding load (H S = 0.219) of H. songaricum indicate a significant extinction risk, and protective measures should be taken immediately.

Pleistocene climate change and phylogeographic structure of the Gymnocarpos przewalskii (Caryophyllaceae) in the northwest China: Evidence from plastid DNA, ITS sequences, and Microsatellite

“…Duo to aridification and orogenic, a large number of deserts and mountains of northwestern China have emerged as effective geographical barriers, resulting in fragmentation of species’ distributions and limited gene flow between fragmentations. Thus, in the populations of many desert plants have higher total genetic diversity but lower within populations genetic diversity, and allopatric divergence has generally been found in desert plants, for example, Ribes meyeri (Xie & Zhang, ), Hexinia polydichotoma (Su, Zhang, & Cohen, ), Helianthemum songaricum (Su, Zhang, & Sanderson, ), Nitraria sphaerocarpa (Su & Zhang, ), and Atraphaxis frutescens (Xu & Zhang, ). Due to dry glacial–humid interglacial cycle in the Quaternary in these regions, many species experienced glacial contraction and postglacial expansion with corresponding climate cycle.…”

Phylogeographical patterns of two closely related desert shrubs,Nitraria roborowskiiandN. sphaerocarpa(Nitrariaceae), from arid north-western China

“…Similarly in eastern China, plants also respond sensitively to climate fluctuation, and regional expansions and multiple glacial refugia in the mountains have been found for several pecies (Qiu et al ., ; Li et al ., ). In north‐western China, species were affected not only by climate oscillations, but also by increasing aridity during the Quaternary (Su, Zhang & Sanderson, ; Li et al ., ). Since the Pliocene, uplifting of the Kunlun Mountains and other ranges of the northern Tibetan Plateau has caused increased aridity in north‐western China because of the increased influence of rain shadows (Zheng et al ., ; Sun et al ., ; Miao et al ., ).…”

Evolutionary response to Quaternary climate aridification and oscillations in north-western China revealed by chloroplast phylogeography of the desert shrubNitraria sphaerocarpa(Nitrariaceae)

“…However, the underlying climate oscillations have had profound effects on the evolutionary history of native species (Meng & Zhang, ; Ma, Zhang & Sanderson, ). In addition, the increasing deterioration of climate to greater states of dryness during the Quaternary is another important factor affecting plant phylogeographical patterns (Meng & Zhang, ; Su, Zhang & Sanderson, ). Thus, the phylogeography of species in these arid lands is expected to be different from that of taxa in the Qinghai–Tibetan Plateau (QTP), where the phylogeography is more affected by factors such as alpine glaciation (Meng et al ., ; Chen et al ., 2008a, b; Yang et al ., ).…”