Pennington R Toby, Cronk Quentin C B, Richardson James A
Royal Botanic Garden Edinburgh, 20a Inverleith Row, Edinburgh EH3 5LR, UK.
Philos Trans R Soc Lond B Biol Sci. 2004 Oct 29;359(1450):1455-64. doi: 10.1098/rstb.2004.1539.
Phylogenetic trees based upon DNA sequence data, when calibrated with a dimension of time, allow inference of: (i) the pattern of accumulation of lineages through time; (ii) the time of origin of monophyletic groups; (iii) when lineages arrived in different geographical areas; (iv) the time of origin of biome-specific morphologies. This gives a powerful new view of the history of biomes that in many cases is not provided by the incomplete plant fossil record. Dated plant phylogenies for angiosperm families such as Leguminoaceae (Fabaceae), Melastomataceae sensu stricto, Annonaceae and Rhamnaceae indicate that long-distance, transoceanic dispersal has played an important role in shaping their distributions, and that this can obscure any effect of tectonic history, previously assumed to have been the major cause of their biogeographic patterns. Dispersal from other continents has also been important in the assembly of the Amazonian rainforest flora and the Australian flora. Comparison of dated biogeographic patterns of plants and animals suggests that recent long-distance dispersal might be more prevalent in plants, which has major implications for community assembly and coevolution. Dated plant phylogenies also reveal the role of past environmental changes on the evolution of lineages in species-rich biomes, and show that recent Plio-Pleistocene diversification has contributed substantially to their current species richness. Because of the critical role of fossils and morphological characters in assigning ages to nodes in phylogenetic trees, future studies must include careful morphological consideration of fossils and their extant relatives in a phylogenetic context. Ideal study systems will be based upon DNA sequence data from multiple loci and multiple fossil calibrations. This allows cross-validation both of age estimates from different loci, and from different fossil calibrations. For a more complete view of biome history, future studies should emphasize full taxon sampling in ecologically important groups, and should focus on geographical areas for which few species-level phylogenies are available, such as tropical Africa and Asia. These studies are urgent because understanding the history of biomes can both inform conservation decisions, and help predict the effects of future environmental changes at a time when biodiversity is being impacted on an unprecedented scale.
基于DNA序列数据构建的系统发育树，若以时间维度进行校准，便可推断出：（i）谱系随时间积累的模式；（ii）单系类群的起源时间；（iii）谱系抵达不同地理区域的时间；（iv）特定生物群落形态的起源时间。这为生物群落的历史提供了全新的有力视角，而这在许多情况下是不完整的植物化石记录所无法提供的。豆科（Fabaceae）、狭义野牡丹科、番荔枝科和鼠李科等被子植物科的定年植物系统发育表明，远距离跨洋扩散在塑造它们的分布格局中发挥了重要作用，而且这可能会掩盖此前被认为是其生物地理格局主要成因的构造历史的任何影响。来自其他大陆的扩散在亚马逊雨林植物群和澳大利亚植物群的形成中也很重要。对植物和动物定年生物地理格局的比较表明，近期远距离扩散在植物中可能更为普遍，这对群落组装和协同进化具有重大影响。定年植物系统发育还揭示了过去环境变化对物种丰富的生物群落中谱系进化的作用，并表明最近上新世 - 更新世的多样化对其当前的物种丰富度有很大贡献。由于化石和形态特征在确定系统发育树节点年龄方面的关键作用，未来的研究必须在系统发育背景下仔细考虑化石及其现存亲属的形态特征。理想的研究系统将基于来自多个基因座和多个化石校准的DNA序列数据。这允许对来自不同基因座和不同化石校准的年龄估计进行交叉验证。为了更全面地了解生物群落历史，未来的研究应强调对生态重要类群进行全面的分类群采样，并应关注物种水平系统发育研究较少的地理区域，如热带非洲和亚洲。这些研究十分迫切，因为了解生物群落的历史既可为保护决策提供信息，又有助于在生物多样性正受到前所未有的影响之际预测未来环境变化的影响。
