Format: ORAL

Lu Liu1, Feifei Wang1, Junyi Ding1, Yuangui Wei1, Wenting Wang2, Julia Lpez-Delgado3, Nian Wang1

1 College of Forestry, Shandong Agricultural University, Tai’an, China 2 School of Mathematics and Computer Science, Northwest Minzu University, Lanzhou, China 3 School of Biology, University of Leeds, Leeds, UK.

Natural hybridization frequently occurs in nature and plays a crucial role in evolution of biodiversity. Here we use the genus Betula to address the following questions: (1) where are their glacial refugia? (2) does hybridization occur between Betula species of various ploidy levels, (3) which environmental variables explain the spatial patterns of genetic admixture? We collected samples representing B. costata (2x), B. dahurica (8x), B. ermanii (4x) and B. platyphylla (2x) in northeast China and B. ashburneri (2x) and B. utilis (4x) from north to southwest China. We integrated microsatellite data of 2,609 individuals, species distribution models and spatial autoregressive models to address these issues. Our results revealed multiple glacial refugia for Betula species. Microsatellite data analysis showed frequent bidirectional genetic admixture among Betula species, irrespective of the ploidy difference. The amount of genetic admixture from either B. costata or B. ermanii to B. platyphylla is partially explained by their overlapped range and from B. dahurica to B. platyphylla is partially explained by precipitation of the coldest quarter (PCQ) and changes in PCQ. The amount of genetic admixture from B. ashburneri to B. utilis is partially explained by the mean temperature of the wettest quarter (MTWQ). Our results show asymmetrical gene flow from high to low ploidy levels and indicate that envrionemtal factors play a role in shaping the patterns of genetic admixture between Betula species.