Evolutionary Hotspots of Seed Plants in Subtropical China: A Comparison With Species Diversity Hotspots of Woody Seed Plants

Abstract

Genetic diversity is a fundamental level of biodiversity. However, it is frequently neglected in conservation prioritization because intraspecific genetic diversity is difficult to measure at large scales. In this study, we synthesized population genetic or phylogeographic datasets of 33 seed plants in subtropical China into multi-species genetic landscapes. The genetic landscapes identified 18 evolutionary hotspots with high within-population genetic diversity (WGD), and among-population genetic diversity (AGD), or both. The western subtropical China is rich in AGD (possessing four major AGD hotspots), deserving a high conservation priority. We found that WGD was positively correlated with longitude, with most WGD hotspots locating in east subtropical China. The results showed that the locations of 12 of 18 evolutionary hotspots corresponded approximately to those of previously identified species diversity (SD) hotspots, however, a positive and significant correlation existed only between AGD and SD, not between WGD and SD. Therefore, spatial patterns of species richness in plants in subtropical China cannot generally be used as surrogate for their intraspecific diversity. This study identified multi-species evolutionary hotspots and correlated multi-species genetic diversity with SD across subtropical China for the first time, providing profound implications for the conservation of biodiversity in this important ecoregion.

Population dynamics linked to glacial cycles in Cercis chuniana F. P. Metcalf (Fabaceae) endemic to the montane regions of subtropical China

“…was inferred with notably increased effective population size (Table S4 , Figure 6 ), indicating high local population diversification as is seen in Figure 3 . The Nanling Mts., which are composed of five distinct ridges, has a long history of subtropical evergreen broadleaved forest (STEBF) in southern China (Fan et al, 2018 ; Xu et al, 2017 ). Its vegetation is characterized by highly varied elevational or longitudinal shifts, varying aspects of slope directions, high heterogeneity of soils, and abundant microhabitats (Huang et al, 2012 ; Qiu et al, 2011 ; Shen et al, 2019 ; Tang et al, 2006 ; Zhu et al, 2017 ), which together served as a buffer from climatic change and thus helped to confer relatively stable ecological conditions to these mountains during glacial periods.…”

Population dynamics linked to glacial cycles in Cercis chuniana F.P. Metcalf (Fabaceae) endemic to the montane regions of southern China

“…was inferred with notably increased effective population size (Table 3, Figure 5), indicating high local population diversification (Figure 3). The Nanling Mts., which are composed of five distinct ridges, has a long history of STEBF in southern China (Fan et al , 2018;Xu et al , 2017). Its vegetation is characterized by highly varied elevational or longitudinal shifts (Shen et al , 2019;Zhu et al , 2017), which confers relatively stable ecological conditions to these mountains during glacial periods and has served as a buffer from climatic change.…”

“…High physiographical heterogeneity is suggested to prompt rapid diversification in montane habitats because of the increased ecological opportunities afforded by frequent episodes of geographic isolation (Colin & Ruth, 2006;Muellner-Riehl, 2019;Simpson, 1964). The high biodiversity of southern China is due in large part to the extreme physiographical heterogeneity of its mountain ranges (Fan et al , 2018;Xu et al, 2017;Yang, Dick, Yao, & Huang, 2016). Often oriented in either north-south or northeast-southwest directions (Hou, 1983;Wang, 1992a;Wang, 1992b;Ying, 2001), these topographically diverse ranges have been suggested to serve as either geographical barriers or colonization corridors for various plant species (Gong et al, 2016;Tian et al, 2018;Xiong, Wu, & Zhang, 2019).…”

Determinants of Genetic Structure in a Highly Heterogeneous Landscape in Southwest China

“…The unique landforms of the LRGR, coupled with the intensified human activities in the region, provide an ideal opportunity to simultaneously test the relative effects of mountain-valley vicariance, the associated climatic variations, and anthropogenic influences on the genetic structure of plant communities. Although the influence of topographic and climatic factors on genetic diversity patterns in some parts of the LRGR (as well as its surroundings) has been explored to a considerable degree ( Gao et al, 2007 ; Li et al, 2011 ; Liu et al, 2013 ; Luo et al, 2017 ; Fan et al, 2018 ; Yu et al, 2019 ), a holistic picture of the entire LRGR is lacking. For instance, the meta-analyses by Fan et al (2018) and Yu et al (2019) incorporated only a few topographic variables (longitude, latitude, and altitude) in their regression analyses and did not consider any climatic or anthropogenic variables, a fact that may have weakened the drawn conclusions.…”

“…Although the influence of topographic and climatic factors on genetic diversity patterns in some parts of the LRGR (as well as its surroundings) has been explored to a considerable degree ( Gao et al, 2007 ; Li et al, 2011 ; Liu et al, 2013 ; Luo et al, 2017 ; Fan et al, 2018 ; Yu et al, 2019 ), a holistic picture of the entire LRGR is lacking. For instance, the meta-analyses by Fan et al (2018) and Yu et al (2019) incorporated only a few topographic variables (longitude, latitude, and altitude) in their regression analyses and did not consider any climatic or anthropogenic variables, a fact that may have weakened the drawn conclusions. Furthermore, most previous studies (e.g., Gao et al, 2007 ; Li et al, 2011 ; Liu et al, 2013 ; Luo et al, 2017 ) were based on single species or taxa, limiting what can be inferred about the general spatial patterns of genetic variation.…”