Diversification process of high mountain oaks with uplift of Himalayas and Quaternary climatic changes

摘要本研究的目的是阐明在喜马拉雅及周边高山植被中占主导地位、被认为是伴随喜马拉雅隆升而进化的栎科（壳斗科）的进化和发展过程。在尼泊尔加德满都和云南西南部地区，通过对沉积物进行筛分，根据化石组合的组成重建古植被和古环境，获得了包括栎科、异巴兰科在内的植物大化石组合。我们的合作伙伴是周zk博士。在中国科学院云南植物研究所进行化石鉴定与讨论。利用日本中部Uonuma群植物大化石组合资料，收集东亚地区上新世—更新世气候波动的地质资料，得到2.4Ma以来的古气候曲线。本文将喜马拉雅地区及周边地区的栎科植物大化石资料与日本地区及周边地区的古气候资料进行了比较。在尼泊尔和中国西南地区的化石组合中，栎科化石与云杉和冷杉一起出现，表明气候寒冷。这表明该剖面在晚上新世以来的冰期扩展了分布，在间冰期被限制在较高的海拔。Momohara et al.（2006）对云南西南部化石组合的描述表明，在上新世晚期的寒冷期，亚高山常绿针叶树和高山高山高山白杨植被的林带分布在比现存海拔低约1000m的高度。因此，晚上新世以来，不仅在日本等中纬度地区，而且在喜马拉雅山和中国南方等低纬度高寒地区，随着冰期-间冰期气候旋回，植被带垂直迁移了约1000 m，并促进了晚新生代以来异obalanus栎科的扩张和物种形成。

The aim of the present research is to clarify the process of the evolution and development of Quercus sect. Heterobalanus (Fagaceae) that dominates in alpine vegetation in and around Himalayas and is considered to have evolved accompanied with uplift of Himalayas. We obtained plant macrofossil assemblages including Quercus sect. Heterobalanus from the Kathmandu, Nepal and southwestern Yunnan by sieving sediments to reconstruct paleovegetation with the paleoenvironments based on composition of the fossil assemblages. We collaborated with Dr. Zhou ZK. in the Yunnan Institute of Botany, Academia Sinica for identification of fossils with the discussion. We collected geological data as for climatic fluctuation in the Plio-Pleistocene in East Asia with data of plant macrofossil assemblages from the Uonuma Group in central Japan to produce paleoclimatic curve since 2.4Ma. We compared plant macrofossil data including Quercus sect. Hetelobalanus in and around Himalayas with the paleoclimatic data in and around Japan. In the fossil assemblages form Nepal and southwest China, fossils of Quercus sect. Hetelobalanus occur with Picea and Abies that indicate cold climate. This shows that this section expanded the distribution in the glacial stages since the late Pliocene and was confined in higher altitudes in the interglacial stages. A fossil assemblage from southwestern Yunnan Province described by Momohara et al. (2006) indicated that the forest zone of subalpine evergreen conifer and alpine Hetelobalanus vegetation was distributed in the altitude about 1000m lower than extant elevation in a late Pliocene cold stage. Thus, the vegetation zones migarate about 1000 m vertically with the glacial-interglacial climatic cycles since the late Pliocene not only in the middle latitudes including Japan but also in alpine areas in lower latitude including Himalayas and southern China and it enhanced the expansion and speciation of Quercus sect. Heterobalanus since the late Cenozoic.