近日，由中國科學(xué)院昆明植物研究所孫航研究員帶領(lǐng)的課題組,，在國家重點基礎(chǔ)研究發(fā)展計劃（973）（2007CB411601）和國家自然科學(xué)基金（30625004, 40930209, 31000101）等項目的資助下，對分布在青藏高原—喜馬拉雅地區(qū)的絹毛苣屬（Soroseris）,、肉菊屬（Stebbinsia）與合頭菊屬（Syncalathium）植物進(jìn)行了分子系統(tǒng)發(fā)育和生物地理學(xué)研究,，其目的在于探究青藏高原地區(qū)植物的物種成因以及進(jìn)化模式。
菊科絹毛苣屬、肉菊屬與合頭菊屬為主要分布于青藏高原高海拔地區(qū)的特有類群,。本研究利用ITS,，trnL-F和psbA-trnH對三屬植物進(jìn)了分子系統(tǒng)學(xué)分析和生物地理學(xué)探討，分析結(jié)果表明,，肉菊應(yīng)該歸并于絹毛苣屬,，而合頭菊屬分為兩支：狹義合頭菊屬（Syncalathium s.str.）與康滇合頭菊（Syncalathium souliei）,，前者位于還陽參亞族,，而后者位于萵苣亞族并與廣義萵苣屬親緣，所以康滇合頭菊應(yīng)該作為Lactuca souliei放回原廣義萵苣屬,，具體分類學(xué)處理將另行發(fā)表（新屬-假合頭菊屬Parasyncalathium）,。
研究同時發(fā)現(xiàn)，這些類群在此區(qū)域存在著三種進(jìn)化模式,，如絹毛苣屬為一快速輻射進(jìn)化而成的類群,；狹義合頭菊屬為替代分布，進(jìn)而發(fā)現(xiàn)其具有異域分化進(jìn)程,，本屬可能是從青藏高原東北部的甘肅,、青海和四川逐步向青藏高原腹地演化；而狹義合頭菊屬與康滇合頭菊間由于同處于青藏高原惡劣的生態(tài)環(huán)境選擇壓力和氣候變化,，進(jìn)而存在形態(tài)趨同進(jìn)化模式,。生物地理學(xué)研究發(fā)現(xiàn)，廣義絹毛苣屬和原合頭菊屬均為年輕的分化類群,，其大概起源和分化時間為1.56—8.44百萬年前,；結(jié)合地質(zhì)學(xué)資料和現(xiàn)有系統(tǒng)學(xué)研究結(jié)果推斷，這些年輕類群應(yīng)該是在青藏高原的隆升過程中隨著環(huán)境的變化和流石灘生境的破碎化而形成,。
該研究成果已在2011年出版的Taxon期刊上發(fā)表,。（生物谷Bioon.com）
生物谷推薦原文出處：
Taxon, Volume 60, Number 1, February 2011 , pp. 15-26(12)
Molecular phylogeny and biogeography of three closely related genera, Soroseris, Stebbinsia, and Syncalathium (Asteraceae, Cichorieae), endemic to the Tibetan Plateau, SW China
Zhang, Jian-Wen; Nie, Ze-Long; Wen, Jun; Sun, Hang
Soroseris, Stebbinsia, and Syncalathium are three genera of the sunflower family (Asteraceae) with restricted distributions on high screes of the Tibetan Plateau. We present a molecular analysis to test the monophyly of the genera, evaluate the phylogenetic relationships and construct their biogeographic diversification history. Nuclear ITS and plastid trnL-F and psbA-trnH fragments were analyzed with parsimony, Bayesian inference, and relaxed Bayesian dating for all species of Soroseris, Stebbinsia, and Syncalathium. Stebbinsia is part of a polytomy with several lineages of Soroseris. Syncalathium is biphyletic with Syn. souliei placed within subtribe Lactucinae and the remaining species close to the Soroseris-Stebbinsia clade within subtribe Crepidinae. Bayesian dating based on ITS sequences and using four fossil calibrations suggests that the stem and crown ages of the Soroseris-Stebbinsia clade and the two groups of Syncalathium are between 8.44 and 1.56 million years. Stebbinsia should be treated as a section of Soroseris and Syncalathium souliei should be excluded from Syncalathium and either placed in Lactuca s.l. or established as a new genus in Lactucinae. The remaining species are to be treated as Syncalathium s.str. in Crepidinae. The diversification of these groups in the Tibetan Plateau is of relatively young age, and can be explained by rapid diversification and radiation of the Soroseris-Stebbinsia clade, allopatric speciation within Syncalathium s.str. and convergent evolution of Syncalathium s.str. and Syn. souliei. The speciation events correlated with climatic change and fragmentation of scree habitats during the uplift of the Tibetan Plateau. Possible migration routes in Syncalathium s.str. from the northeast to the central and southern part of the Tibetan Plateau are suggested.
