Al Scott Prize Lecture
Fri, 05/01/2020 - 3:00pm
Abstract: Large asexual populations often have complicated evolutionary dynamics due to their large influxes of beneficial mutations. Competition between the lineages that arise leads to a loss of many beneficial mutations, a phenomenon referred to as clonal interference. Several alleles and loci are involved in this process, which has made the study of asexual adaptation with clonal interference challenging to undertake. Traveling wave models in population genetics overcome these challenges. Over the last two decades, their application has significantly advanced our understanding of asexual adaptation, with several key results that shed light on how population parameters shape rates of adaptation, levels of genetic diversity, and the structures of genealogies. To study asexual adaptation with two fitness-associated traits, we developed a new two-dimensional traveling model that builds on the work of Desai and Fisher (2007). Our simulations and analysis of this model lead to two major results: First, the long-term features of trait interactions from clonal interference appear like functional constraints limiting trait evolution. Second, the stalling of evolution in a trait from clonal interference with another is dependent on both mutation rates and the fitness effects they confer, which challenges the selection-driven view of asexual adaptation.