Modeling How Selection in One Trait Interferes with Adaptation in Another
When beneficial mutations appear rapidly, distinct beneficial mutations often compete rather than combine, because they are linked to different genetic backgrounds. Without recombination, only beneficial mutations occurring on the fittest (relatively low frequency) genetic backgrounds contribute. Traveling waves have been used to quantify the resulting rate of adaptation under asexual reproduction (Desai & Fisher 2007), with all beneficial mutations interchangeable (evolution in one trait dimension of “relative fitness”). We developed a two-dimensional traveling wave model, and used it to quantify the negative genetic correlations arising between fitness-related traits as a consequence of linkage disequilibria, determining the extent to which adaptation in one trait is slowed by adaptation in the other. The genotype-fitness landscape not only affects the speed of adaptive evolution directly through mutation rates and selection coefficients, but also indirectly by shaping linkage disequilibria between loci encoding different adaptive traits. Simulations are used to confirm our analytical results.