title: Multiple glacial refugia for cool-temperate deciduous trees in northern East Asia: the Mongolian oak as a case study.
abstract: In East Asia, temperate forests are predicted to have retracted southward to c. 30° N during the last glacial maximum (LGM) based on fossil pollen data, whereas phylogeographic studies have often suggested glacial in situ survival of cool-temperate deciduous trees in their modern northern ranges. Here we report a study of the genetic diversity and structure of 29 natural Mongolian oak (Quercus mongolica) populations using 19 nuclear simple sequence repeat (nSSR) loci and four chloroplast DNA fragments. Bayesian clustering analysis with nSSRs revealed five groups, which were inferred by approximate Bayesian computation (ABC) to have diverged in multiple refugia through multiple glacial-interglacial cycles. Analysis of chloroplast DNA variation revealed four lineages that were largely but incompletely geographically disjunct. Ecological niche modelling (ENMs) indicated a southward range shift of the oak's distribution at the LGM, although high suitability scores were also evident in the Changbai Mts. (Northeast China), the Korean Peninsula, areas surrounding the Bohai Sea, and along the coast of the Russian Far East. In addition, endemic chloroplast DNA haplotypes and nuclear lineages occurred in high-latitude northern areas where the ENM predicted no suitable habitat. The combined evidence from nuclear and chloroplast DNA, and the results of the ENM clearly demonstrate that multiple northern refugia, including cryptic ones, were maintained across the current distributional range of the Mongolian oak during the LGM or earlier glacial periods. Though spatially limited, postglacial expansions from these refugia have led to a pattern of decreased genetic diversity with increasing latitude.
authors.affiliation: State Key Laboratory of Tree Genetics and Breeding, Chinese Academy of Forestry, Beijing, 100091, China.|Key Laboratory of Silviculture of the State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, 100091, China.
authors.forename: Yan-Fei
authors.initials: YF
authors.lastname: Zeng
authors.affiliation: MOE Key Laboratory for Biodiversity Science and Ecological Engineering, Beijing Normal University, Beijing, 100875, China.|School of Mathematics and Computer Science, Northwest University for Nationalities, Lanzhou, 730030, China.
authors.forename: Wen-Ting
authors.initials: WT
authors.lastname: Wang
authors.affiliation: MOE Key Laboratory for Biodiversity Science and Ecological Engineering, Beijing Normal University, Beijing, 100875, China.
authors.forename: Wan-Jin
authors.initials: WJ
authors.lastname: Liao
authors.affiliation: MOE Key Laboratory for Biodiversity Science and Ecological Engineering, Beijing Normal University, Beijing, 100875, China.
authors.forename: Hong-Fang
authors.initials: HF
authors.lastname: Wang
authors.affiliation: MOE Key Laboratory for Biodiversity Science and Ecological Engineering, Beijing Normal University, Beijing, 100875, China.
authors.forename: Da-Yong
authors.initials: DY
authors.lastname: Zhang
mesh_terms: D001499:Bayes Theorem; D005075:Biological Evolution; D002980:Climate; D018742:DNA, Chloroplast / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D017753:Ecosystem; D005202:Asia, Eastern; D014644:Genetic Variation; D005828:Genetics, Population; D005838:Genotype; D018895:Microsatellite Repeats; D008957:Models, Genetic; D058974:Phylogeography; D029963:Quercus / Q000235:genetics*; D000068236:Refugium; D017422:Sequence Analysis, DNA
chemical_list: D018742:DNA, Chloroplast; D018744:DNA, Plant
keywords: East Asia; Quaternary glaciations; ecological niche modelling; molecular variation; northern refugia; temperate forest