PloS ONE：版纳植物园生态组揭示血桐属和野桐属植物传播进化模式

中国科学院西双版纳热带植物园生态进化生物学研究组重建和分析了血桐属和野桐属这两个大分子种属的数据。发现这两个属的传播模式基本一致，从而证实了对分化时间的预测。相关文章发表于2014年1月17日的《PLoS ONE》杂志上。



PLOS ONE：版纳植物园生态组揭示血桐属和野桐属植物传播进化模式

中国科学院西双版纳热带植物园生态进化生物学研究组的博士后Joeri及其合作者(荷兰Leiden大学自然生物多样性中心)利用贝叶斯钟重建和分析了血桐属和野桐属这两个大分子种属的数据。利用不同的分子标记、多个化石校准点以及不同的样本，他们重建了这两个属植物的进化历史、分化的地理模式和时间。

研究者们使用RASP以及生物地理和地理记录的比较结果作出了祖先区域构建模型，对两个属植物的分布和分化模式进行了对比分析。

血桐属和野桐属在分布事件上有高度的时间和地理同质性。从某种程度上说，这不是意料之外的推测。因为他们具有非常相近的生态结构，有类似的地理分布以及近期的共同祖先，潜在地导致了它们在相当接近的生物和非生物情况下的存在和分化。

在Joeri的研究中，特别注意到了两属植物的组装DNA序列数据包具有高度的相似性。这些数据包的分子年代测定结果证实了生物地理重建得到的结论，即当有大量的DNA序列一致性存在时，传播一致性会增加。

研究得到的结果与现有的地理数据一致，显示了两属植物从婆罗洲到新几内亚和亚洲大陆，通过陆地传播到非洲和马达加斯加，再经由印度洋岛链回传到印度的传播途径。

虽然现存物种分布显示的总体模式、传播和分化速度有较大的差别，但两个属的传播模式基本一致，从而证实了对分化时间的预测。研究结果还表明在例如大戟科这种近源物种丰富的种群中，存在一致性进化且十分迅速，并能够跨越地理距离和环境差异造成的障碍。

原文摘要：

Dated Phylogenies of the Sister Genera Macaranga and Mallotus(Euphorbiaceae): Congruence in Historical Biogeographic Patterns?

Peter C. van Welzen, Joeri S. Strijk, Johanna H. A. van Konijnenburg-van Cittert, Monica Nucete, Vincent S. F. T. Merckx

Molecular phylogenies and estimates of divergence times within the sister genera Macarangaand Mallotus were estimated using Bayesian relaxed clock analyses of two generic data sets, one per genus. Both data sets were based on different molecular markers and largely different samples. Per genus three calibration points were utilised. The basal calibration point (crown node of all taxa used) was taken from literature and used for both taxa. The other three calibrations were based on fossils of which two were used per genus. We compared patterns of dispersal and diversification in Macaranga and Mallotus using ancestral area reconstruction in RASP (S-DIVA option) and contrasted our results with biogeographical and geological records to assess accuracy of inferred age estimates. A check of the fossil calibration point showed that the Japanese fossil, used for dating the divergence of Mallotus, probably had to be attached to a lower node, the stem node of all pioneer species, but even then the divergence time was still younger than the estimated age of the fossil. The African (only used in theMacaranga data set) and New Zealand fossils (used for both genera) seemed reliably placed. Our results are in line with existing geological data and the presence of stepping stones that provided dispersal pathways from Borneo to New Guinea-Australia, from Borneo to mainland Asia and additionally at least once to Africa and Madagascar via land and back to India via Indian Ocean island chains. The two genera show congruence in dispersal patterns, which corroborate divergence time estimates, although the overall mode and tempo of dispersal and diversification differ significantly as shown by distribution patterns of extant species.

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