Chloroplast phylogeography of the East Asian Arcto‐Tertiary relict Tetracentron sinense (Trochodendraceae)

Abstract

Aim A phylogeographical study of the widespread but phylogenetically isolated East Asian endemic tree species Tetracentron sinense (Trochodendraceae) was performed to evaluate whether and how Pleistocene and pre‐Pleistocene climate changes helped to influence current phylogeographical patterns, and to describe the current patterns of genetic diversity and their implications for conservation. Location Southwestern and central subtropical China. Methods Sequences of four chloroplast spacer regions were obtained from 157 individuals of T. sinense. A haplotype network was constructed using tcs. Genetic diversity and differentiation, spatial analysis of molecular variance (SAMOVA) and analysis of molecular variance (AMOVA) were used to test for genetic structure. beast was used to estimate the divergence times between haplotypes. Historical demographic expansion was tested using pairwise mismatch distribution analysis. Results Of the 21 recovered haplotypes, three were widely distributed, but most were restricted to particular regions. Populations with high haplotype diversity were located in western Hubei, southern Sichuan and southern Chongqing. The two earliest‐diverging haplotypes were found in southwestern China. The haplotype distribution of T. sinense demonstrated significant phylogeographical structure (NST > GST; P < 0.05). The best partitioning of genetic diversity by SAMOVA (K = 5) produced groups that matched the main tcs‐derived clades. Two independent range expansions within SAMOVA‐derived groups 2 and 3 were dated to approximately 399 and 311 ka, respectively. The time to the most recent common ancestor of all haplotypes was 9.6 (95% highest posterior density: 27.0–2.2) Ma, but most of the haplotype diversity appeared during the Quaternary. Main conclusions The extant distribution of T. sinense is likely to have been shaped by both pre‐Quaternary and Pleistocene climate changes. Southwestern China may have served as an important refugium for T. sinense throughout the Neogene, while the species also occupied multiple refugia during the late Pleistocene glacial periods. Populations of T. sinense were resolved into five allopatric groups, between which there is apparently no seed movement.

Phenotypic diversity in natural populations of an endangered plant <em>Tetracentron sinense</em>

“…Similar results have been reported on Rosa praelucens, Coptis teeta, Reaumuria soongarica and Miscanthus sinensis (Guan et al 2012, Yang et al 2013, Xiao et al 2013. Meanwhile, the results from cpDNA marker in T. sinense also showed that phenotypic variation mainly resulted from the variation among populations (Sun et al 2014). The cause may be correlated to the distinctive environment in different populations.…”

“…Among the 11 populations of T. sinense, the CV of phenotypic traits in WFHH was the highest, indicating the relatively abundant phenotypic diversity, which was in consistent with the result from cpDNA marker (Sun et al 2014). The reason may be correlated to the geographical position and topography.…”

“…The result showed that the phenotypic differentiation among populations in T. sinense is at moderate level. Sun et al (2014) also reported the higher genetic differentiation among populations in this species based on cpDNA marker. In this study, the CV of total phenotypic variation among populations in T. sinense varied from 2.92 to 7.50, and the mean is only 4.80, which is significantly lower than that in other endangered plants, such as Rosa praelucens, Coptis teeta, Ulmus lamellose, Calycanthus chinensis , Huang et al 2011), indicating the popularly lower level of phenotypic diversity in T. sinense.…”

“…Recently, the current situation of genetic diversity in wild populations of T. sinense was assessed based on the chloroplast DNA (Sun et al 2014). However, molecular and phenotypic classifications often disagree.…”

Molecular phylogeny, biogeography and ecological niche modelling ofCardiocrinum(Liliaceae): insights into the evolutionary history of endemic genera distributed across the Sino-Japanese floristic region

“…In particular, patterns of plant dispersal/migration have emerged, such as north-to-south migration to the Himalaya-Hengduan Mountains for some ArctoTertiary floristic elements (H. Sun, 2002a, b; Y. X. Sun et al, 2014), migration from Southwest China to other regions along mountain corridors for numerous groups containing taxa distributed across East Asia (Wang, 1992), migration from South China to Southeast Asia for some genera distributed in the subtropics and tropics Wen, 2013, 2014), and migration between East China and Japan via the exposed East China Sea land bridge for some herbs, shrubs and trees with disjunct distributions in these areas (Qiu et al, 2009a(Qiu et al, , b, c, 2011Sakaguchi et al, 2012). The driving mechanisms of species divergence in the SJFR have been widely discussed.…”