The most significant difference setting human apart from other animal species is the highly developed cognitive ability. During genome evolution, rapid sequence substitutions were observed in some of the cognition-related genes, which is due to the act of Darwinian positive selection.
CLMN is related to dendrites elongation during neuron development. In this study, we sequenced and compared the coding region and the flanking sequences of CLMN in three major human populations and five non-human primate species. The results indicated that CLMN evolved faster in the human lineage when compared with nonhuman primates. We identified three human specific sequence substitutions, which are fixed in human populations and located in the function-unknown domain of CLMN. Among the 15 polymorphic sites found in human populations, two of the derived substitutions have high frequency (93% and 88%), so is the haplotype defined by these two substitutions (35%). As the two substitutions are located in the intron region, it is likely that the observed high frequencies were caused by genetic hitch-hiking. In addition, neutrality test in human populations revealed the signature of adaptive evolution due to Darwinian positive selection.
In summary, we demonstrated that CLMN has undergone Darwinian positive selection during human origin, which may contribution to the functional change in human cognitive abilities.
修改评论