Abstract

The tenets underlying the use of mtDNA in phylogenetic and systematic analyses are strict maternal inheritance, clonality, homoplasmy, and difference due to mutation: that is, there are species-specific mtDNA sequences and phylogenetic reconstruction is a matter of comparing these sequences and inferring closeness of relatedness from the degree of sequence similarity. Yet, how mtDNA behavior became so defined is mysterious. Even though early studies of fertilization demonstrated for most animals that not only the head, but the sperm’s tail and mitochondria-bearing midpiece penetrate the egg, the opposite – only the head enters the egg – became fact, and mtDNA conceived as maternally transmitted. When midpiece/tail penetration was realized as true, the conceptions ‘strict maternal inheritance’, etc., and their application to evolutionary endeavors, did not change. Yet there is mounting evidence of paternal mtDNA transmission, paternal and maternal combination, intracellular recombination, and intra- and intercellular heteroplasmy. Clearly, these phenomena impact the systematic and phylogenetic analysis of mtDNA sequences.

摘要

在系统发育和系统分析中使用 mtDNA 的基本原则是严格的母系遗传、克隆性、同质性和突变引起的差异：也就是说，存在物种特异性 mtDNA 序列，系统发育重建是比较这些序列并推断接近度的问题从序列相似程度来判断相关性。然而，mtDNA 行为是如何变得如此明确的却是个谜。尽管早期的受精研究表明，对于大多数动物来说，不仅头部，而且精子的尾巴和带有线粒体的中段都穿透了卵子，但相反的情况——只有头部进入了卵子——成为了事实，并且 mtDNA 被认为是母系传播的。当中段/尾部穿透被实现为真实时，“严格的母系遗传”等概念及其在进化努力中的应用，没有改变。然而，越来越多的证据表明父系 mtDNA 传递、父系和母系结合、细胞内重组以及细胞内和细胞间异质性。显然，这些现象影响了 mtDNA 序列的系统和系统发育分析。