School of Physics Soft Condensed Matter & Biophysics Seminar: Prof. Edo Kussell, New York University

DNA sequences evolve under many locus-specific pressures that modify protein functions, expression levels, and gene regulation. We show that DNA sequences also adapt globally under an evolutionary force that tunes the frequency of short DNA motifs. We argue that DNA binding processes that are present in all domains of life give rise to distinct global pressures in different genomes. This global selection has a universal hallmark that we detect in all sequenced genomes, with selective coefficients that are on average only slightly higher than point mutation rates. We show that global selection operates through tiny selective steps over evolutionary timescales spanning millions of years, and is responsible for an ancient phylogenetic signal in DNA sequences. Importantly, this process can efficiently increase fitness only when recombination is present. We conclude that global selection provides a ubiquitous selective advantage for recombination and sex.