The nanopore sequencing of a Chinese rhesus macaque revealed patterns of methylation, recombination, and selection for structural variations

Abstract

Rhesus macaques (Macaca mulatta) are the most extensively studied nonhuman primate species for human biomedical modeling. However, little is known about the biological pattern of genome-wide structural variations (SVs) and the evolutionary forces underlying SVs. Here, we conducted genomic sequencing and analyses based on Nanopore long reads and Illumina short reads technology. We called SVs between the two subspecies (China vs. India), using three methods of assembly-based and long-reads-based algorithms. Interestingly, we found significantly more SVs in X-chromosome than in autosomes, consistent with the expectation of the faster-X divergence at the subspecies level. With the fine-scale methylation frequencies and recombination rates, we found duplications with significantly lower methylation frequencies while higher recombination rates than other types of SVs, suggesting a higher level of transcriptional and evolutionary potential for duplications than for other SVs types. A genome-wide scan of selective sweep revealed that over 3% of SVs are under positive selection. Moreover, X chromosome showed significantly higher number of positively selected SVs than do autosomes, suggesting the "faster-X effect" of SVs. Our study revealed a different evolutionary importance for duplications compared with other SVs forms. We also revealed the "faster-X effect" of SVs, which could provide raw material upon which positive selection can further play.