Genetic Structure and Evolutionary History of Three Alpine Sclerophyllous Oaks in East Himalaya-Hengduan Mountains and Adjacent Regions.

Li Feng,Gui-Fang Zhao,Zhong-Hu Li,Qi-Jian Zheng,Jia Yang,Zeng-Qiang Qian,Yan-Ping Zhang

doi:10.3389/fpls.2016.01688

Abstract

The East Himalaya-Hengduan Mountains (EH-HM) region has a high biodiversity and harbors numerous endemic alpine plants. This is probably the result of combined orographic and climate oscillations occurring since late Tertiary. Here, we determined the genetic structure and evolutionary history of alpine oak species (including Quercus spinosa, Quercus aquifolioides, and Quercus rehderiana) using both cytoplasmic-nuclear markers and ecological niche models (ENMs), and elucidated the impacts of climate oscillations and environmental heterogeneity on their population demography. Our results indicate there were mixed genetic structure and asymmetric contemporary gene flow within them. The ENMs revealed a similar demographic history for the three species expanded their ranges from the last interglacial (LIG) to the last glacial maximum (LGM), which was consistent with effective population sizes changes. Effects of genetic drift and fragmentation of habitats were responsible for the high differentiation and the lack of phylogeographic structure. Our results support that geological and climatic factors since Miocene triggered the differentiation, evolutionary origin and range shifts of the three oak species in the studied area and also emphasize that a multidisciplinary approach combining molecular markers, ENMs and population genetics can yield deep insights into diversification and evolutionary dynamics of species.

Highlights

Historical processes such as geographic and climate changes have profoundly shaped the population genetic structure and demographic history of extant species (Hewitt, 2000)
Estimates of average within-species haplotype diversity was highest in Q. spinosa (Hd = 0.927)
N3 and N5 occurred across the three species, N1 and N4 were unique to Q. aquifolioides, while Q. rehderiana and Q. spinosa possessed two (N13 and N14) and five private ribotypes (N8-N12), respectively (Figure S1A and Table S3)

Summary

Introduction

Historical processes such as geographic and climate changes have profoundly shaped the population genetic structure and demographic history of extant species (Hewitt, 2000). Evolutionary History of Alpine Oaks suggested that environmental heterogeneity may contribute to the genetic differentiation among species or populations (e.g., Ortego et al, 2012, 2015; Guichoux et al, 2013). In China, phylogeographic studies have focus mainly on the roles of historical orogenesis, climatic oscillations and environmental heterogeneity in evolutionary history of biotas in Qinghai-Tibet Plateau (QTP) and adjacent regions (Qiu et al, 2011; Liu et al, 2012; Wen et al, 2014). Recent study has suggested that the demographic history of flora occurred in the QTP must be revised because the QTP has been 4–5 km high since the midEocene while numerous studies linked young inferred divergence times to recent QTP uplift phases ( see review by Renner (2016) and references therein)

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