Department of Integrative Biology & Biodiversity Institute of Ontario, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada.
School of Biological Sciences and Applied Chemistry, Seneca College, 1750 Finch Ave E, North York, ON, M2J 2X5, Canada.
Heredity (Edinb). 2019 May;122(5):513-524. doi: 10.1038/s41437-018-0141-7. Epub 2018 Sep 10.
The evolutionary speed hypothesis (ESH) suggests that molecular evolutionary rates are higher among species inhabiting warmer environments. Previously, the ESH has been investigated using small numbers of latitudinally-separated sister lineages; in animals, these studies typically focused on subsets of Chordata and yielded mixed support for the ESH. This study analyzed public DNA barcode sequences from the cytochrome c oxidase subunit I (COI) gene for six of the largest animal phyla (Arthropoda, Chordata, Mollusca, Annelida, Echinodermata, and Cnidaria) and paired latitudinally-separated taxa together informatically. Of 8037 lineage pairs, just over half (51.6%) displayed a higher molecular rate in the lineage inhabiting latitudes closer to the equator, while the remainder (48.4%) displayed a higher rate in the higher-latitude lineage. To date, this study represents the most comprehensive analysis of latitude-related molecular rate differences across animals. While a statistically-significant pattern was detected from our large sample size, our findings suggest that the EHS may not serve as a strong universal mechanism underlying the latitudinal diversity gradient and that COI molecular clocks may generally be applied across latitudes. This study also highlights the merits of using automation to analyze large DNA barcode datasets.
进化速度假说（ESH）认为，生活在温暖环境中的物种的分子进化速度更高。以前，使用数量较少的纬度分离姐妹谱系对 ESH 进行了研究；在动物中，这些研究通常集中在脊索动物的子集上，对 ESH 的支持不一。本研究分析了来自六个最大动物门（节肢动物门、脊索动物门、软体动物门、环节动物门、棘皮动物门和刺胞动物门）的细胞色素 c 氧化酶亚基 I（COI）基因的公共 DNA 条码序列，并通过信息学方法对纬度分离的分类群进行配对。在 8037 个谱系对中，略超过一半（51.6%）的谱系在更接近赤道的纬度上生活时显示出更高的分子速率，而其余（48.4%）的谱系在高纬度谱系中显示出更高的速率。迄今为止，这项研究代表了对动物中与纬度相关的分子速率差异的最全面分析。虽然从我们的大样本量中检测到了一个具有统计学意义的模式，但我们的研究结果表明，ESH 可能不是导致纬度多样性梯度的强大普遍机制，并且 COI 分子钟通常可以在整个纬度范围内应用。这项研究还强调了使用自动化分析大型 DNA 条码数据集的优点。
