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

本研究旨在厘清栎属学派的演化与发展过程。异叶壳斗属(壳斗科)，主要生长在喜马拉雅山脉及其周围的高山植被中，被认为是随着喜马拉雅山脉的隆起而进化的。我们获得了包括栎组在内的植物大型化石组合。来自加德满都、尼泊尔和云南西南部的Heterobalanus，通过筛选沉积物，根据化石组合的组成重建古植被和古环境。我们与周至康博士合作。在中科院云南植物研究所进行化石鉴定的讨论。我们收集了东亚地区上更新世以来的气候波动地质资料，并结合日本中部上沼群的植物大型化石组合资料，绘制了2.4 Ma以来的古气候曲线。我们比较了包括栎组在内的植物宏观化石数据。喜马拉雅山及周边地区的Hetelobalanus与日本及周边地区的古气候资料。在尼泊尔和中国西南地区的化石组合中，发现了栎属化石。Hetelobalanus与云杉和冷杉一起出现，表明气候寒冷。这表明该剖面扩大了晚上新世以来冰期的分布范围，并局限于间冰期的较高海拔地区。Momohara等人描述的云南西南部化石组合。(2006)的研究表明，亚高山常绿针叶树和高山常绿针叶树植被林带分布在海拔1000m左右的上新世晚期寒冷期。因此，上新世晚期以来，不仅包括日本在内的中纬度地区，而且包括喜马拉雅山脉和中国南部在内的低纬度高山地区，植被带与冰期-间冰期气候旋回垂直偏移约1000m，促进了栎组的扩展和物种形成。晚新生代以来的异叶藻。

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.