Phylogeographic pattern suggests a general northeastward dispersal in the distribution of Machilus pauhoi in South China

Abstract

Machilus pauhoi Kanehira is an important timber species in China. A provenance trial was recently set up to evaluate the growth performance of trees from different localities, with the aim of designing seed transfer guidelines. Here, we tested twelve nuclear microsatellite markers derived from other species of the Lauraceae family and investigated population genetic structure in M. pauhoi. Both the number of observed alleles per locus (Na) and the polymorphic information content (PIC) significantly decreased against the latitude, but showed an insignificant decrease against the longitude. Heterozygosity (Ho) and gene diversity (h) exhibited a weak correlation with geographic location. Private alleles were present in multiple populations, and a moderate level of population genetic differentiation was detected (Gst = 0.1691). The joint pattern of genetic diversity (Na, PIC, Ho, and h) suggests that general northeastward dispersal led to the current distribution of M. pauhoi. Significant but weak effects of isolation-by-distance (IBD) occurred, implicating the mountain ranges as the major barrier to gene flow. Both STRUCTURE and hierarchical clustering analyses showed three distinct groups of populations related to the physical connectivity among mountain ranges. A priority in designing genetic conservation should be given to the populations at the southwest side of the species’ distribution. This conservation strategy can also be combined with the pattern of adaptive genetic variation from the provenance trial for comprehensive genetic resource management of native M. pauhoi.

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

“…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. The Nanling Mts.…”

Implications of genetic heterogeneity for plant translocation during ecological restoration

“…However, to date, no published study has documented this in plant species. Several studies have found significant effects of topographic barriers on genetic differentiation in plant species, including seas (Jaros et al., 2017), lakes and terrain (Ju et al., 2018), rivers (Geng et al., 2015), mountains (Reeves & Richards, 2014; Zhu et al., 2017), and basins (Bontrager & Angert, 2018). Our data agree with these studies and indicate that populations from opposite sides of the Continental Divide are genetically more isolated, despite spatial proximity (Figure 3).…”

Implications of genetic heterogeneity for plant translocation during ecological restoration

“…However, to date, no published study has documented this in plant species. Many studies have found significant effects of geographic barriers on genetic differentiation in plant species, including: seas (Jaros et al, 2017), lakes and terrain (Ju et al, 2018), rivers (Geng et al, 2015), mountains (Zhu et al, 2017; Reeves and Richards, 2014), and basins (Bontrager and Angert, 2018). Our data agree with these studies and indicate that populations from opposite sides of the Continental Divide are genetically isolated, despite what may appear to be close geographic proximity (Fig.…”