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Abstract：
Genetic changes that enabled the evolution of eusociality have long captivated biologists. More recently, attention has focussed on the consequences of eusociality on genome evolution. Studies have reported higher molecular evolutionary rates in eusocial hymenopteran insects compared with their solitary relatives. To investigate the genomic consequences of eusociality in termites, we analysed nine genomes, including newly sequenced genomes from three non-eusocial cockroaches. Using a phylogenomic approach, we found that termite genomes have experienced lower rates of synonymous substitutions than those of cockroaches, possibly as a result of longer generation times. We identified higher rates of non-synonymous substitutions in termite genomes than in cockroach genomes, and identified pervasive relaxed selection in the former (24-31% of the genes analysed) compared with the latter (2-4%). We infer that this is due to reductions in effective population size, rather than gene-specific effects (e.g. indirect selection of caste-biased genes). We found no obvious signature of increased genetic load in termites, and postulate efficient purging of deleterious alleles at the colony level. Additionally, we identified genomic adaptations that may underpin caste differentiation, such as genes involved in post-translational modifications. Our results provide insights into the evolution of termites and the genomic consequences of eusociality more broadly.
摘要：
长期以来，生物学家一直迷住了遗传变化，这些变化使人们得以进化。最近,人们的注意力集中在现代性对基因组进化的影响上。研究报告说，与单亲相比，社会性膜翅目昆虫的分子进化率更高。为了研究白蚁的eusociality的基因组后果，我们分析了九个基因组,包括三个非社会性蟑螂的新测序基因组。使用系统学方法，我们发现白蚁基因组的同义替换率低于蟑螂，可能是由于更长的世代时间。我们发现白蚁基因组中的非同义替换率高于蟑螂基因组，与后者（2-4％）相比，前者（分析的基因的24-31％）确定了普遍的宽松选择。我们推断这是由于有效人口规模的减少，而不是基因特异性效应(例如种姓偏见基因的间接选择)。我们没有发现白蚁遗传负荷增加的明显特征，并假设在菌落水平上有效清除有害等位基因。此外,我们确定了可能支持种姓分化的基因组适应，如参与翻译后修饰的基因。我们的结果更广泛地提供了对白蚁进化和eusociality基因组后果的见解。
