Fitness functions, genetic and non-genetic inheritance, and why ecological dynamics and evolution are inevitably linked

Fitness functions are at the heart of ecology and evolution as they simultaneously determine both population dynamics and the strength of selection. We link the Breeders and Price equations with structured population models constructed from fitness functions to show how ecological and evolutionary dynamics are intimately linked. Analyses of our models reveal i) how multi-generational predictions of evolution are sensitive to assumptions about phenotypic plasticity and non-genetic inheritance, ii) that factors that reduce the per time-step population growth rate such as negative density-dependence and antagonistic species interactions are generally expected to accelerate rates of evolution compared to cases when they are absent, iii) that evolution is expected to occur fastest when it is cryptic (all other things being equal) and iv) that eco-evolutionary dynamics are likely widespread and can be studied using evolutionarily explicit structured population models.