selection
Kern AD & Hahn MW 2018 The neutral theory in light of natural selection. Mol Biol Evol 35:1366-1371.
- the neutral theory was supported by unreliable theoretical and empirical evidence from the beginning
- in light of modern, genome-scale data, we can firmly reject its universality
- the neutral theory instead posits a positive thesis about nature:
- differences between species are due to neutral substitutions (not adaptive evolution)
- polymorphisms within species are not only neutral but also have dynamics dominated by mutation-drift equilibrium
- one of the most striking impacts of natural selection on genomes is the near universal correlation between rates of recombination and levels of polymorphism
- adaptive evolution is not mutation-limited in natural populations
- instead, selection from standing variation may be the typical response to an environmental shift
- modern evidence for soft sweeps and adaptive introgression suggest that the supply of beneficial mutations will not be a major limiting factor over evolutionary time
- phenotypes that are highly polygenic (i.e., that result from genetic contributions at many loci) might not be associated with fixation of advantageous alleles at all
- for a large number of evolutionarily important phenotypes, searching for selective sweeps might be an effort made in vain
