Capybara (Hydrochoerus hydrochaeri) is the largest species among the extant rodents. The draft genome of capybara was sequenced with the estimated genome size of 2.6 Gb. Although capybara is about 60 times larger than guinea pig, comparative analyses revealed that the neutral evolutionary rates of the two species were not substantially different. However, analyses of 39 mammalian genomes revealed very heterogeneous evolutionary rates. The highest evolutionary rate, 8.5 times higher than the human rate, was found in the Cricetidae–Muridae common ancestor after the divergence of Spalacidae. Muridae, the family with the highest number of species among mammals, emerged after the rate acceleration. Factors responsible for the evolutionary rate heterogeneity were investigated through correlations between the evolutionary rate and longevity, gestation length, litter frequency, litter size, body weight, generation interval, age at maturity, and taxonomic order. The regression analysis of these factors showed that the model with three factors (taxonomic order, generation interval, and litter size) had the highest predictive power (R² = 0.74). These three factors determine the number of meiosis per unit time. We also conducted transcriptome analysis and found that the evolutionary rate dynamics affects the evolution of gene expression patterns.

中文翻译：

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水豚草案基因组序列分析揭示了哺乳动物进化速率的动力学，原因和影响。

水豚（Hydrochoerus hydrochaeri）是现存啮齿动物中最大的物种。对水豚的基因组草图进行测序，估计的基因组大小为2.6 Gb。尽管水豚大约是豚鼠的60倍，但比较分析显示这两种物种的中性进化速率没有实质性差异。但是，对39个哺乳动物基因组的分析显示出非常不同的进化速率。在Spalacidae发生分歧之后，Cricetidae-Muridae的共同祖先发现了最高的进化速率，比人类的进化速率高8.5倍。速率加快后，出现了鼠科（Muriidae），这是哺乳动物中种类最多的科。通过进化率与寿命，妊娠期长度，产仔频率，生育率之间的相关性，研究了导致进化率异质性的因素。产仔数，体重，生育间隔，成熟年龄和分类顺序。这些因素的回归分析表明，具有三个因素（分类顺序，世代间隔和产仔数）的模型具有最高的预测能力（R ² = 0.74）。这三个因素决定了单位时间内的减数分裂次数。我们还进行了转录组分析，发现进化速率动力学影响基因表达模式的进化。