In it for the long haul: evolutionary consequences of persistent endosymbiosis.
In it for the long haul: evolutionary consequences of persistent endosymbiosis.
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DOI：
10.1016/j.gde.2017.08.006
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发表时间：
2017-12
影响因子：
4
通讯作者：
J. Wernegreen
中科院分区：
文献类型：
--
作者：
J. Wernegreen
昆虫持久的内共生体为研究宿主-细菌相互作用的进化提供了有价值的模型。比较基因组学揭示了塑造内共生体进化的过程，包括与生活方式相关的遗传漂移和突变的变化。内共生体基因组的退化可能限制宿主-细菌伙伴关系对环境变化的反应能力。系统发育独立的细菌谱系经历了深刻的生活方式转变：从自由生活转变为与宿主相关的存在。在这些谱系中，昆虫的细胞内细菌互助体是已知的最亲密、最受限制的共生体之一。这些专性内共生菌表现出严重的基因丢失和明显的基因组退化。进化理论提供了一个基础，将它们不同寻常的基因组特征与基本机制的变化--选择、遗传漂移、突变和重组--联系起来。这篇简短的综述强调了最近对这些古老协会内形成正在进行的多样化的过程的比较和实验研究。最近的工作支持随机过程对退化进化的明显贡献，包括遗传漂移和异常强大的突变压力。尽管可能存在补偿机制，但基因组退化可能会限制持久性内共生菌(及其宿主)对环境波动的反应。
HighlightsPersistent endosymbionts of insects offer valuable models to study the evolution of intimate host–bacterial interactions.Comparative genomics has shed light on processes shaping endosymbiont evolution, including lifestyle-associated shifts in genetic drift and mutation.Genome deterioration in endosymbionts may constrain the ability of host–bacterial partnerships to respond to environmental change.Phylogenetically independent bacterial lineages have undergone a profound lifestyle shift: from a free-living to obligately host-associated existence. Among these lineages, intracellular bacterial mutualists of insects are among the most intimate, constrained symbioses known. These obligate endosymbionts exhibit severe gene loss and apparent genome deterioration. Evolutionary theory provides a basis to link their unusual genomic features with shifts in fundamental mechanisms—selection, genetic drift, mutation, and recombination. This mini-review highlights recent comparative and experimental research of processes shaping ongoing diversification within these ancient associations. Recent work supports clear contributions of stochastic processes, including genetic drift and exceptionally strong mutational pressure, toward degenerative evolution. Despite possible compensatory mechanisms, genome degradation may constrain how persistent endosymbionts (and their hosts) respond to environmental fluctuations.