TY - JOUR TI - Admixture of evolutionary rates across a butterfly hybrid zone PB - eLIFE SCIENCES PUBL LTD Y1 - 2022/06/15/ N1 - Copyright © et al. This article is distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use and redistribution provided that the original author and source are credited. ID - discovery10165520 JF - eLife SN - 2050-084X UR - https://doi.org/10.7554/eLife.78135 A1 - Xiong, Tianzhu A1 - Li, Xueyan A1 - Yago, Masaya A1 - Mallet, James KW - Science & Technology KW - Life Sciences & Biomedicine KW - Biology KW - Life Sciences & Biomedicine - Other Topics KW - hybridization KW - reproductive isolation KW - molecular clock KW - gene flow KW - Other KW - DIVERGENT SELECTION KW - MUTATION-RATE KW - GENE FLOW KW - HYBRIDIZATION KW - POPULATION KW - SPECIATION KW - REVEALS KW - ROAD N2 - Hybridization is a major evolutionary force that can erode genetic differentiation between species, whereas reproductive isolation maintains such differentiation. In studying a hybrid zone between the swallowtail butterflies Papilio syfanius and Papilio maackii (Lepidoptera: Papilionidae), we made the unexpected discovery that genomic substitution rates are unequal between the parental species. This phenomenon creates a novel process in hybridization, where genomic regions most affected by gene flow evolve at similar rates between species, while genomic regions with strong reproductive isolation evolve at species-specific rates. Thus, hybridization mixes evolutionary rates in a way similar to its effect on genetic ancestry. Using coalescent theory, we show that the rate-mixing process provides distinct information about levels of gene flow across different parts of genomes, and the degree of rate-mixing can be predicted quantitatively from relative sequence divergence (FST ) between the hybridizing species at equilibrium. Overall, we demonstrate that reproductive isolation maintains not only genomic differentiation, but also the rate at which differentiation accumulates. Thus, asymmetric rates of evolution provide an additional signature of loci involved in reproductive isolation. VL - 11 EP - 31 AV - public ER -