Genome Evolution of Asexual Organisms and the Paradox of Sex in Eukaryotes
Genome Evolution of Asexual Organisms and the Paradox of Sex in Eukaryotes
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DOI：
10.1007/978-3-030-57246-4_7
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发表时间：
2020
期刊：
影响因子：
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通讯作者：
E. Hörandl;Jens Bast;Alexander Brandt;S. Scheu;C. Bleidorn;Mathilde Cordellier;M. Nowrousian;D. Begero
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文献类型：
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作者：
E. Hörandl;Jens Bast;Alexander Brandt;S. Scheu;C. Bleidorn;Mathilde Cordellier;M. Nowrousian;D. Begero
真核生物的性别优势仍然是个谜。性，减数分裂和混合周期的组成过程，赋予高成本，但选择优势仍然不清楚。在这篇综述中，我们重点关注无性生殖对基因组进化的潜在有害影响。理论预测，无性系应该遭受缺乏减数分裂DNA修复，有害突变的积累，转座因子的增殖等。在这里，我们比较了不同的基因组特征，生命周期，发育途径和细胞学机制的主要真核生物群，即，原生生物、动物、真菌和植物。总的来说，很难把无性恋的血统特征和一般特征区分开来。在所有群体中，无性恋的形式主要是兼性的或周期性的。存在多种混合或部分性发育途径，维持性的某些成分，而专性无性似乎在真核生物中很少见。对于无性恋的负面后果，最强有力的理论预测是与性行为相比，选择的有效性降低。虽然一些研究表明无性恋者的突变积累率增加，但其他使用全基因组比较的研究没有发现这种模式。存在可以减轻负突变积累的负面后果的各种机制。需要更多的经验数据来全面了解基因组进化对维持性别的作用。
The predominance of sex in eukaryotes is still enigmatic. Sex, a composed process of meiosis and mixis cycles, confers high costs but the selective advantages remain unclear. In this review, we focus on potentially detrimental effects of asexuality on genome evolution. Theory predicts that asexual lineages should suffer from lack of meiotic DNA repair, accumulation of deleterious mutations, proliferation of transposable elements, among others. Here, we compare the different genomic features, life cycles, developmental pathways, and cytological mechanisms in the major eukaryotic groups, i.e., in protists, animals, fungi, and plants. In general, it is difficult to disentangle lineage-specific features from general features of asexuality. In all groups, forms of asexuality are predominantly facultative or cyclical. A variety of mixed or partial sexual developmental pathways exists, maintaining some components of sexuality, while obligate asexuality appears to be rare in eukaryotes. The strongest theoretical prediction for negative consequences of asexuality is decreased effectiveness of selection compared to sexuality. While some studies have shown increased rates of mutation accumulation in asexuals, others using whole-genome comparisons did not find this pattern. Various mechanisms exist that can alleviate the negative consequences of accumulation of negative mutations. More empirical data are needed to understand comprehensively the role of genome evolution for the maintenance of sex.