Estimating the timing of early eukaryotic diversification with multigene molecular clocks
Estimating the timing of early eukaryotic diversification with multigene molecular clocks
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DOI：
10.1073/pnas.1110633108
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发表时间：
2011-08-16
影响因子：
11.1
通讯作者：
Katz, Laura A.
中科院分区：
文献类型：
--
作者：
Parfrey, Laura Wegener;Lahr, Daniel J. G.;Katz, Laura A.
虽然肉眼可见的植物、动物和真菌是最常见的真核生物，但真核生物多样性的大部分是微生物。阐明70多个谱系多样化的时间是理解真核生物进化的关键。在这里，我们使用分类丰富的多基因数据，结合不同的化石和宽松的分子时钟框架，估计现存真核生物的最后共同祖先的时间和主要分支的分歧。总的来说，这些分析表明，最后一个共同祖先生活在1866年至1679年之间，这与最早的微化石一致，并有信心解释为真核生物。在此期间，地球的表面与今天有明显的不同;例如，海洋不完全通风，含铁和大约1800 Ma后的硫化物水团通常位于适度含氧的表面沃茨之下。我们的时间估计还表明，真核生物的主要分支分歧前1000马，大部分或全部可能分歧前1200马。然而，化石表明，主要现存分支内的多样性后来扩大，大约从800 Ma开始，当海洋开始向更现代的化学状态过渡时。古生物学和分子生物学的结合表明，在主要的真核生物谱系中，长茎先于多样化。
Although macroscopic plants, animals, and fungi are the most familiar eukaryotes, the bulk of eukaryotic diversity is microbial. Elucidating the timing of diversification among the more than 70 lineages is key to understanding the evolution of eukaryotes. Here, we use taxon-rich multigene data combined with diverse fossils and a relaxed molecular clock framework to estimate the timing of the last common ancestor of extant eukaryotes and the divergence of major clades. Overall, these analyses suggest that the last common ancestor lived between 1866 and 1679 Ma, consistent with the earliest microfossils interpreted with confidence as eukaryotic. During this interval, the Earth's surface differed markedly from today; for example, the oceans were incompletely ventilated, with ferruginous and, after about 1800 Ma, sulfidic water masses commonly lying beneath moderately oxygenated surface waters. Our time estimates also indicate that the major clades of eukaryotes diverged before 1000 Ma, with most or all probably diverging before 1200 Ma. Fossils, however, suggest that diversity within major extant clades expanded later, beginning about 800 Ma, when the oceans began their transition to a more modern chemical state. In combination, paleontological and molecular approaches indicate that long stems preceded diversification in the major eukaryotic lineages.