Our weekly lunch seminar series featuring internal speakers in the field of ecology and evolutionary biology.

Abstract
A key factor limiting our understanding of early crown bird evolution is a complex history of molecular evolution linked to the Cretaceous–Paleogene (K–Pg) mass extinction and associated changes in life history parameters. Here, we assess molecular heterogeneity across crown bird phylogeny using a new technique, enabling inferred sequence substitution models to transition across the history of a clade. Our approach identifies contrasting patterns among exons, introns, untranslated regions, and mitochondrial genomes that reflect distinct regimes of molecular evolution across the avian phylogeny. Up to fifteen molecular shifts map to rapidly diversifying clades near the end-Cretaceous boundary, demonstrating an "early burst" of genomic disparity. Using simulation and machine learning techniques, we show that shifts in developmental mode or adult body mass best explain transitions in the mode of nucleotide substitution. We further connect these patterns to macroevolutionary shifts in the allometric scaling relationship between basal metabolic rate and body mass. In agreement with theoretical predictions, we show that this scaling relationship became weaker across the end-Cretaceous transition. Thus, our study provides evidence that the Chicxulub bolide impact triggered integrated patterns of evolution across avian genomes, physiology, and life history that structured the evolutionary potential of modern birds.

This seminar will be in-person and livestreaming on Zoom (link this page). Contact eebsemaccess@umich.edu for Zoom password at least 2 hours prior to event.

Image: Steve Day CC BY-SA 2.0