A molecular time-scale for eukaryote evolution recalibrated with the continuous microfossil record
A molecular time-scale for eukaryote evolution recalibrated with the continuous microfossil record
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DOI：
10.1098/rspb.2006.3537
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发表时间：
2006-08-07
影响因子：
4.7
通讯作者：
Pawlowski, Jan
中科院分区：
文献类型：
--
作者：
Berney, Cedric;Pawlowski, Jan
最近试图建立一个真核生物进化的分子时间尺度未能提供一个一致的观点，真核生物的起源和早期多样化的时间。分子时间估计的主要差异与树的校准问题有关。为了限制这些不确定性，我们在这里使用作为校准点的源源的甲藻，硅藻和颗石藻的丰富和连续的微体化石记录。我们校准了真核生物的小亚基核糖体RNA树，具有4个最大和22个最小的时间限制。使用这些多个校准点在贝叶斯宽松的分子钟框架，我们推断，真核生物的早期辐射发生在中元古代-新元古代边界附近，约11亿年前。我们的研究结果表明，大多数可能的真核生物起源的元古宙化石不能自信地分配到现存的谱系，因此不应该被用作分子测年的校准点。
Recent attempts to establish a molecular time-scale of eukaryote evolution failed to provide a congruent view on the timing of the origin and early diversification of eukaryotes. The major discrepancies in molecular time estimates are related to questions concerning the calibration of the tree. To limit these uncertainties, we used here as a source of calibration points the rich and continuous microfossil record of dinoflagellates, diatoms and coccolithophorids. We calibrated a small-subunit ribosomal RNA tree of eukaryotes with four maximum and 22 minimum time constraints. Using these multiple calibration points in a Bayesian relaxed molecular clock framework, we inferred that the early radiation of eukaryotes occurred near the Mesoproterozoic-Neoproterozoic boundary, about 1100 million years ago. Our results indicate that most Proterozoic fossils of possible eukaryotic origin cannot be confidently assigned to extant lineages and should therefore not be used as calibration points in molecular dating.