neutrality

Bromham L 2009 Does nothing in evolution make sense except in the light of population genetics? Biol Phil 24:387-403.

  • if you want to understand biological evolution, you should have at least a passing familiarity with evolutionary change at the level of the genome
  • this is not to say that everyone interested in evolution should be a geneticist or a bioinformatician, but that a working knowledge of genetic change is an essential part of the intellectual toolkit of modern evolutionary biology, even if your primary focus is the evolution of behaviour or the diversity of communities
  • this book provides excellent examples of another important tool in the biologist's intellectual toolkit, but one that is rarely explained or illustrated to such an extent: null (or neutral) models
  • this book provides grist for the mill for the important debate about whether population genetic processes are the sine qua non of evolutionary explanations
  • Lynch turns the selection-for-complexity argument on its head
  • genome complexity is disadvantageous
  • genomic complexity evolves because organisms with small population sizes do not have the selective power to stop it
  • complexity evolved not by selection for better organisms, but due to the failure of natural selection to maintain simplicity
  • this tension is most evident in Lynch's annoyance with the vague but enthusiastic claims arising from the growing field of evolutionary development (evo-devo) that the Neodarwinian synthesis is inadequate (without demonstrating where it fails) and that they will furnish a new and better theory (without having done so yet)
  • evo-devo provides an example of the kind of evolutionary biology that Lynch does not like
  • it is a field almost entirely devoid of population genetics
  • more deeply, evo-devo hypotheses generally do not even include a discussion of how variations that appear in individuals could rise in frequency in the population by drift or selection until they replaced the wild-type
  • developmental biologists, on the whole, give no consideration to the theoretical framework that suggests mutations of large effect can rarely go to fixation, nor to the interaction between population size and selective co-efficient in determining the fate of mutations
  • evo-devo jumps from the mutation in an individual to the substitution in a lineage with little formal consideration of the process in-between
  • it does not follow that no biologist can skip the population genetic stage if they wish to explain the origin of a trait
  • in an ideal world, we could furnish a complete explanation of the evolution of any trait, from its mutational origins to its developmental and phenotypic expression, its interaction with the environment and its rise or fall in frequency the population by selection or drift, followed by a complete history of the species bearing that trait as they compete with other species, respond to changing environment, speciate and go extinct
  • the majority of biologists that study macroevolution do so with the assumption that the microevolutionary processes that can be described by the population genetic framework underlie all macroevolutionary phenomena
  • we often cannot get the data to test this assumption
  • some questions we wish to ask may be best pursued by other means