Evolutionary neutrality of mtDNA introgression: evidence from complete mitogenome analysis in roe deer
Evolutionary neutrality of mtDNA introgression: evidence from complete mitogenome analysis in roe deer
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DOI：
10.1111/jeb.12491
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发表时间：
2014-11-01
影响因子：
2.1
通讯作者：
Borkowska, A.
中科院分区：
文献类型：
--
作者：
Matosiuk, M.;Sheremetyeva, I. N.;Borkowska, A.
渐渗杂交为研究作用于有丝分裂基因组的自然选择的分子基础提供了一个独特的平台。大多数线粒体DNA蛋白编码基因都极其保守；然而，一些观察到的变化具有潜在的适应性意义。在这里，我们评估了受广泛 mtDNA 渗入影响的密切相关的狍物种中 mtDNA 的进化是否是中性的或适应性的。我们对欧洲 (Capreolus capreolus) 和西伯利亚 (C.pygargus) 狍的 16 个完整线粒体基因组进行了表征和比较，其中包括 4 个源自西伯利亚的狍，渐渗到欧洲物种中。物种特异性谱系的平均序列差异估计为 2.8%，并且不同基因类别之间存在差异。在蛋白质编码基因中发现的 315 个固定差异中，只有 21 个代表非同义变化。自两个狍属物种最近的共同祖先（TMRCA）以来，只有三个被确定为在 C.pygargus 谱系中出现，反映了进化比率的减慢。欧洲狍系的 d(N)/d(S) 比率几乎高出四倍，受到整体纯化选择的限制，尤其是在 ND4 和 ND5 基因中尤为明显。我们认为高度分化的C.capreolus谱系可能保持了基因组掺入C.pygargus中保存完好且几乎是祖先类型的mtDNA的能力。我们的分析没有表明西伯利亚狍 mtDNA 存在任何正向选择的迹象，这表明目前广泛的基因渗入在进化上是中性的。
Introgressive hybridization offers a unique platform for studying the molecular basis of natural selection acting on mitogenomes. Most of the mtDNA protein-coding genes are extremely conserved; however, some of the observed variations have potentially adaptive significance. Here, we evaluated whether the evolution of mtDNA in closely related roe deer species affected by widespread mtDNA introgression is neutral or adaptive. We characterized and compared 16 complete mitogenomes of European (Capreolus capreolus) and Siberian (C.pygargus) roe deer, including four of Siberian origin introgressed into European species. The average sequence divergence of species-specific lineages was estimated at 2.8% and varied across gene classes. Only 21 of 315 fixed differences identified in protein-coding genes represented nonsynonymous changes. Only three of them were determined to have arisen in the C.pygargus lineage since the time to the most recent common ancestor (TMRCA) of both Capreolus species, reflecting a decelerated evolutionary ratio. The almost four-fold higher d(N)/d(S) ratio described for the European roe deer lineage is constrained by overall purifying selection, especially pronounced in the ND4 and ND5 genes. We suggest that the highly divergent C.capreolus lineage could have maintained a capability for genomic incorporation of the well-preserved and almost ancestral type of mtDNA present in C.pygargus. Our analyses did not indicate any signs of positive selection for Siberian roe deer mtDNA, suggesting that the present widespread introgression is evolutionarily neutral.