GC-biased gene conversion drives accelerated evolution of ultraconserved elements in mammalian and avian genomes

Accelerated evolution and gBGC of UCEs in mammals. (A) Number of fast-evolving UCEs (red) and gBGC-induced fast-evolving UCEs (green) in specific mammalian lineages (red dots). (B) Distribution of substitution numbers in fast-evolving UCEs of all species. (C) Distribution of substitution numbers in gBGC-induced fast-evolving UCEs of all species. The substitution numbers of each fast-evolving UCE and gBGC-induced fast-evolving UCE were counted according to the mutation direction, including S → W type and W → S type. The x-axis indicates the number of W → S substitutions: [n(W → S)]. S → W substitutions were scored as negative values.