Data from: Rates of genomic divergence in humans, chimpanzees and their lice

The rate of DNA mutation and divergence is highly variable across the tree
of life. However, the reasons underlying this variation are not well
understood. Comparing the rates of genetic changes between hosts and
parasite lineages that diverged at the same time is one way to begin to
understand differences in genetic mutation and substitution rates. Such
studies have indicated that the rate of genetic divergence in parasites is
often faster than that of their hosts when comparing single genes.
However, the variation in this relative rate of molecular evolution across
different genes in the genome is unknown. We compared the rate of DNA
sequence divergence between humans, chimpanzees and their ectoparasitic
lice for 1534 protein-coding genes across their genomes. The rate of DNA
substitution in these orthologous genes was on average 14 times faster for
lice than for humans and chimpanzees. In addition, these rates were
positively correlated across genes. Because this correlation only occurred
for substitutions that changed the amino acid, this pattern is probably
produced by similar functional constraints across the same genes in
humans, chimpanzees and their ectoparasites.

DNA突变率与序列分化率在生命之树的各个类群中存在高度变异。然而，该变异背后的成因尚未得到充分阐释。比较同时分化的宿主与寄生虫谱系的遗传变化速率，是探索遗传突变与替换速率差异的有效途径之一。已有相关研究表明，在单基因水平上进行对比时，寄生虫的遗传分化速率通常快于其宿主。但目前学界对于基因组内不同基因间的分子进化相对速率的变异情况仍不明确。本研究针对人类、黑猩猩及其体外寄生虱的全基因组范围内的1534个蛋白质编码基因，开展了DNA序列分化速率的比较分析。结果显示，这些同源基因（orthologous genes）的DNA替换速率平均而言，虱子的替换速率是人类与黑猩猩的14倍。此外，不同基因间的替换速率呈正相关关系。由于该相关性仅存在于引发氨基酸改变的替换中，这种模式可能源于人类、黑猩猩及其体外寄生虫的同源基因间存在相似的功能约束。