题  目：Natural hybridisation and phylogeny of Betula(Betulaceae)

桦木属植物自然杂交与系统发育的研究

报告人：王  年（伦敦大学皇后学院  分子生态学博士）

时  间：2016年1月23日（周六）上午9：00

地  点：林学院（7号楼）106会议室

报告摘要：

    Hybridisation and polyploidy are important in the evolution of species. The genus Betula L. is an ideal model to study these processes as species of this genus hybridise frequently and polyploid species are common. A cline of introgression of microsatellite marker alleles from B. nana was found extending into B. pubescens populations far to the south of the current B. nanarange in Britain. We suggest that this genetic pattern is a footprint of a historical decline and/or northwards shift in the range of B. nana populations due to climate warming in the Holocene.

    The taxonomy of the genus Betula is debated and a new classification has been proposed in a recent monograph.We evaluated it using ITS and restriction site associated DNA sequencing (RADSeq).The result based on ITS largely agrees with species classification in the recent monograph but with uncertainties. Phylogenomic analysis of 587 RAD loci for Betula diploid species using coalescence-based methods, a concatenation method and binary presence/absence of RAD loci produced well-resolved trees with similar topology. Based on these analyses, we propose a new classification of Betula into four subgenera and seven sections. Further research is needed to infer the parental origins of polyploid species within Betula.

                                                                                                                                    林学院

                                                                                                                                   2016.1.21