Yuan Qing-Jun, Zhang Zhi-Yong, Peng Hua, Ge Song
Laboratory of Biodiversity and Biogeography, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan 650204, China.
Mol Ecol. 2008 Feb;17(4):1054-65. doi: 10.1111/j.1365-294X.2007.03628.x. Epub 2008 Jan 14.
The evolutionary history of plants in the southeast Tibetan Plateau might be the most complicated around the world because of the area's extremely complex topography and climate induced by strong tectonic activity in recent history. In this research, we implemented a phylogeographical study using chloroplast sequences (psbA-trnH and trnQ-rps16 intergenic spacer) on Dipentodon, a monotypic or ditypic genus (D. sinicus and D. longipedicellatus) distributed in southwest China and adjacent areas including Myanmar (Burma), northeast India and northern Vietnam. A total of 257 samples from 16 populations from the southeast Tibetan Plateau (D. longipedicellatus) and the Yungui Plateau (D. sinicus) were collected. The results revealed that Dipentodon had 11 haplotypes for the two intergenic spacers, high genetic diversity (h(T) = 0.902) and high genetic differentiation (N(ST) = 0.987 and G(ST) = 0.948). amova analysis showed that the component of among-population within region/species (55.25%) was unexpectedly larger than the among-species/region component (43.69%), which indicates that there is no justification for recognizing two species in Dipentodon. Correlation of pairwise genetic and geographical distances showed that Dipentodon populations in the southeast Tibetan Plateau may have suffered more habitat fragmentation than populations in the Yungui Plateau because of the uplift of the Tibetan Plateau than populations in the Yungui Plateau have. Nested clade analysis showed that 11 haplotypes formed two 3-level, three 2-level and seven 1-level clades, with eight clades showing significant geographical association. However, clade 2-1 and 2-2 did not cluster together, although they are distributed in the same region (Yungui Plateau) and belong to the same species (D. sinicus). This led not only to incongruence between haplotype network and geographical distribution of 2-level clades, but also to paraphyly of D. sinicus to D. longipedicellatus. We concluded that the incongruence and paraphyly may result from incomplete lineage sorting during the rapid and extreme tectonic events of the Tibetan Plateau. The results reported here will no doubt provide new insights into the evolution of biodiversity on the Tibetan Plateau and adjacent areas, and a historical framework for the conservation of biodiversity in this area, including Dipentodon.
由于青藏高原东南部近期受强烈构造活动影响，地形和气候极其复杂，该地区植物的进化史可能是全球最为复杂的。在本研究中，我们利用叶绿体序列（psbA - trnH和trnQ - rps16基因间隔区）对十齿花属进行了系统发育地理学研究。十齿花属是一个单型或二型属（单花十齿花和长梗十齿花），分布于中国西南部及包括缅甸、印度东北部和越南北部在内的邻近地区。我们从青藏高原东南部（长梗十齿花）和云贵高原（单花十齿花）的16个种群中总共采集了257个样本。结果显示，十齿花属的两个基因间隔区共有11个单倍型，具有高遗传多样性（h(T) = 0.902）和高遗传分化（N(ST) = 0.987，G(ST) = 0.948）。方差分析表明，区域/物种内种群间的组分（55.25%）意外地大于物种/区域间的组分（43.69%），这表明没有理由将十齿花属划分为两个物种。成对遗传距离与地理距离的相关性表明，由于青藏高原的隆升，青藏高原东南部的十齿花属种群可能比云贵高原的种群遭受了更多的栖息地破碎化。嵌套分支分析表明，11个单倍型形成了两个3级、三个2级和七个1级分支，其中八个分支显示出显著的地理关联。然而，分支2 - 1和2 - 2虽然分布在同一区域（云贵高原）且属于同一物种（单花十齿花），但它们并未聚类在一起。这不仅导致了2级分支的单倍型网络与地理分布不一致，还导致了单花十齿花相对于长梗十齿花的并系性。我们得出结论，这种不一致和并系性可能是青藏高原快速而剧烈的构造事件期间不完全谱系分选的结果。本文报道的结果无疑将为青藏高原及邻近地区生物多样性的进化提供新的见解，并为该地区生物多样性保护（包括十齿花属）提供一个历史框架。
