Middle-Upper Pleistocene climate changes shaped the divergence and demography of Cycas guizhouensis (Cycadaceae): Evidence from DNA sequences and microsatellite markers

Abstract

Climatic oscillations in the Pleistocene have had profound effects on the demography and genetic diversity of many extant species. Cycas guizhouensis Lan & R.F. Zou is an endemic and endangered species in Southwest China that is primarily distributed along the valleys of the Nanpan River. In this study, we used four chloroplast DNAs (cpDNA), three nuclear genes (nDNA) and 13 microsatellite (SSR) loci to investigate the genetic structure, divergence time and demographic history of 11 populations of C. guizhouensis. High genetic diversity and high levels of genetic differentiation among the populations were observed. Two evolutionary units were revealed based on network and Structure analysis. The divergence time estimations suggested that haplotypes of C. guizhouensis were diverged during the Middle-Upper Pleistocene. Additionally, the demographic histories deduced from different DNA sequences were discordant, but overall indicated that C. guizhouensis had experienced a recent population expansion during the post-glacial period. Microsatellite data revealed that there was a contraction in effective population size in the past. These genetic features allow conservation measures to be taken to ensure the protection of this endangered species from extinction.

Tectonic and climatic impacts on the biota within the Red River Fault, evidence from phylogeography of Cycas dolichophylla (Cycadaceae)

“…These two chlorotypes escaping from southwest lineage was best explained by the local adaptation to novel selective pressures during the species’ range expansion into geographically and ecologically different environments. However, the missing of ten interior haplotypes was mainly due to the species’ long evolutionary history during historical climate oscillations, geological as well as recent human activities 25 26 .…”

The distribution, diversity, and conservation status of Cycas in China

“…Based on Bayesian Skyline Plot, a scenario of population expansion was suggested for both C. revoluta and C. taitungensis (Chiang et al., ), which contrary to the contraction experience occurred on southeast Asia Cycas species (Feng, Zheng, & Gong, ; Feng, Liu, et al., ; Gong et al., ; Zheng et al., ). One possible reason for this contrast is the different evolutionary processes of both topography and species in history (Gong et al., ; Huang et al., ; Kizaki & Oshiro, ; Shaw & Huang, ).…”

Late Pleistocene speciation of three closely related tree peonies endemic to the Qinling–Daba Mountains, a major glacial refugium in Central China

“…It is widely known that climatic fluctuations during the Pleistocene strongly impacted the distribution and genetic structure of plant and animal species in both Northern and Southern Hemispheres (Hewitt, 2004;Lu, Heckel, Liang, & Zhang, 2013;Song et al, 2009). Although China experienced less severe glaciations during this period relative to Europe and North America (López-Pujol, Zhang, Sun, Ying, & Ge, 2011;Qian & Ricklefs, 1999Rost, 2000), climatic oscillations nonetheless affected the genetic diversity and evolution of many extant species in the region (Feng, Zheng, & Gong, 2016;Song et al, 2009;Zhou et al, 2010). Recent phylogeographic surveys in China indicate that during Pleistocene glaciations montane species might frequently have persisted in topographically complex regions that served as refugia, rather than being restricted only to lower latitudes Liu et al, 2013;Qiu, Fu, & Comes, 2011;Song et al, 2009;Zhou et al, 2010).…”