A DIVERGENCE DATING ANALYSIS OF TURTLES USING FOSSIL CALIBRATIONS: AN EXAMPLE OF BEST PRACTICES
A DIVERGENCE DATING ANALYSIS OF TURTLES USING FOSSIL CALIBRATIONS: AN EXAMPLE OF BEST PRACTICES
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DOI：
10.1666/12-149
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发表时间：
2013-07-01
影响因子：
1.4
通讯作者：
Donoghue, Philip C. J.
中科院分区：
文献类型：
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作者：
Joyce, Walter G.;Parham, James F.;Donoghue, Philip C. J.
海龟已经成为使用化石校准进行分子分歧定年研究的模型系统。然而，由于龟类化石记录的某些部分是众所周知的，从分子生物学中估计的分歧年龄通常与直接从化石记录中观察到的差异不大。此外，在以前的研究中使用的海龟化石校准的系统发育位置和年龄没有得到充分的证明。我们提供了第一个明确合理的最小和软最大年龄限制22支海龟最佳实践协议。利用这些数据，我们进行了贝叶斯放松分子钟分析，建立了一个时间尺度的冠龟，我们利用试图解决进化问题，不能单独用化石解决的进化。其中一些问题，例如龟冠是否起源于三叠纪或侏罗纪，无法通过我们的分析来解决。然而，我们的研究结果产生了新的年龄起源估计冠龟类内的分支。最后，我们将我们的化石校准和后验年龄估计与其他研究进行比较，揭示了结果和解释的实质性差异。
Turtles have served as a model system for molecular divergence dating studies using fossil calibrations. However, because some parts of the fossil record of turtles are very well known, divergence age estimates from molecular phylogenies often do not differ greatly from those observed directly from the fossil record alone. Also, the phylogenetic position and age of turtle fossil calibrations used in previous studies have not been adequately justified. We provide the first explicitly justified minimum and soft maximum age constraints on 22 clades of turtles following best practice protocols. Using these data we undertook a Bayesian relaxed molecular clock analysis establishing a timescale for the evolution of crown Testudines that we exploit in attempting to address evolutionary questions that cannot be resolved with fossils alone. Some of these questions, such as whether the turtle crown originated in the Triassic or Jurassic, cannot be resolved by our analysis. However, our results generate novel age-of-origination estimates for clades within crown Testudines. Finally, we compare our fossil calibrations and posterior age estimates to those from other studies, revealing substantial differences in results and interpretation.