TY - JOUR T1 - Molecular early burst associated with the diversification of birds at the K–Pg boundary JF - bioRxiv DO - 10.1101/2022.10.21.513146 SP - 2022.10.21.513146 AU - Jacob S. Berv AU - Sonal Singhal AU - Daniel J. Field AU - Nathanael Walker-Hale AU - Sean W. McHugh AU - J. Ryan Shipley AU - Eliot T. Miller AU - Rebecca T. Kimball AU - Edward L. Braun AU - Alex Dornburg AU - C. Tomomi Parins-Fukuchi AU - Richard O. Prum AU - Benjamin M. Winger AU - Matt Friedman AU - Stephen A. Smith Y1 - 2023/01/01 UR - http://biorxiv.org/content/early/2023/05/01/2022.10.21.513146.abstract N2 - Complex patterns of genome and life-history evolution associated with the end-Cretaceous (K– Pg) mass extinction event limit our understanding of the early evolutionary history of crown group birds [1-9]. Here, we assess molecular heterogeneity across living birds using a technique enabling inferred sequence substitution models to transition across the history of a clade [10]. Our approach identifies distinct and contrasting regimes of molecular evolution across exons, introns, untranslated regions, and mitochondrial genomes. Up to fifteen shifts in the mode of avian molecular evolution map to rapidly diversifying clades near the Cretaceous-Palaeogene boundary, demonstrating a burst of genomic disparity early in the evolutionary history of crown birds [11-13]. Using simulation and machine learning techniques, we show that shifts in developmental mode [14] or adult body mass [4] best explain transitions in the mode of nucleotide substitution. These patterns are related, in turn, to macroevolutionary shifts in the allometric scaling relationship between basal metabolic rate and body mass [15, 16]. In agreement with theoretical predictions, this scaling relationship appears to have weakened across the end-Cretaceous transition. Overall, our study provides evidence that the Chicxulub bolide impact [17] triggered integrated patterns of evolution across avian genomes, physiology, and life history that structured the evolutionary potential of modern birds.Competing Interest StatementThe authors have declared no competing interest. ER -