Multiple origins and rapid evolution of duplicated mitochondrial genes in parthenogenetic geckos (Heteronotia binoei; squamata, gekkonidae)
Multiple origins and rapid evolution of duplicated mitochondrial genes in parthenogenetic geckos (Heteronotia binoei; squamata, gekkonidae)
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DOI：
10.1093/molbev/msm212
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发表时间：
2007-12-01
影响因子：
10.7
通讯作者：
Moritz, Craig
中科院分区：
文献类型：
--
作者：
Fujita, Matthew K.;Boore, Jeffrey L.;Moritz, Craig
越来越多的证据表明，脊椎动物线粒体基因组的进化动态比以前认为的要大。单性生殖蜥蜴的一些谱系包含大量的串联复制，包括rRNA， tRNA和蛋白质编码基因，以及控制区。这种重复被假设为基因重排的中间阶段，但它们进化的早期阶段以前没有研究过。为了更好地理解线粒体DNA复制片段的进化动力学，我们对10个线粒体基因组进行了测序，这些线粒体基因组来自最近形成的（类似于30万年前）Heteronotia binoei复合体的杂交孤雌壁虎，1个来自有性形式的壁虎。这些基因组包括一些具有典型脊椎动物的排列，另一些具有串联重复，大小从5.7 kb到9.4 kb不等，每个基因组具有不同的基因含量和重复终点。这些结果，连同系统发育分析，表明了重复的独立和频繁的起源。在复制端点上的小而直接的重复意味着链滑错误是一种产生复制的机制，而不是DNA复制的错误起始/终止机制，这种机制被用来解释其他蜥蜴线粒体系统的复制。尽管它们的起源较晚，但有证据表明基因的非功能化主要是由于缺失，并且观察到的基因破坏模式支持mtDNA基因顺序重排的复制-缺失模型。相反，这些最近的重复序列之间的突变积累没有提供基因转换的证据，而在其他一些系统中已经报道过。这些结果表明，尽管在某些谱系中基因含量和排列长期停滞，脊椎动物线粒体基因组即使在短时间尺度上也可以是动态进化的。
Accumulating evidence for alternative gene orders demonstrates that vertebrate mitochondrial genomes are more evolutionarily dynamic than previously thought. Several lineages of parthenogenetic lizards contain large, tandem duplications that include rRNA, tRNA, and protein-coding genes, as well as the control region. Such duplications are hypothesized as intermediate stages in gene rearrangement, but the early stages of their evolution have not been previously studied. To better understand the evolutionary dynamics of duplicated segments of mitochondrial DNA, we sequenced 10 mitochondrial genomes from recently formed (similar to 300,000 years ago) hybrid parthenogenetic geckos of the Heteronotia binoei complex and 1 from a sexual form. These genomes included some with an arrangement typical of vertebrates and others with tandem duplications varying in size from 5.7 to 9.4 kb, each with different gene contents and duplication endpoints. These results, together with phylogenetic analyses, indicate independent and frequent origins of the duplications. Small, direct repeats at the duplication endpoints imply slipped-strand error as a mechanism generating the duplications as opposed to a false initiation/termination of DNA replication mechanism that has been invoked to explain duplications in other lizard mitochondrial systems. Despite their recent origin, there is evidence for nonfunctionalization of genes due primarily to deletions, and the observed pattern of gene disruption supports the duplication-deletion model for rearrangement of mtDNA gene order. Conversely, the accumulation of mutations between these recent duplicates provides no evidence for gene conversion, as has been reported in some other systems. These results demonstrate that, despite their long-term stasis in gene content and arrangement in some lineages, vertebrate mitochondrial genomes can be evolutionary dynamic even at short timescales.