neutrality
Koonin EV 2016 Splendor and misery of adaptation, or the importance of neutral null for understanding evolution. BMC Biol 14:114.
- careful estimates of the fraction of nucleotides in mammalian genomes that are subject to selection, as assessed by evolutionary conservation, produce values of 6 to 9%
- no more than 10% of the genome qualifies as functional
- under the key assumption that selection equals functionality
- nothing in biology makes sense except in the light of evolution
- this famous pronouncement of Theodosius Dobzhansky [32, 33] is by now embraced by all biologists
- (at least at the level of lip service)
- an essential extension to this statement is not nearly as widely recognized
- it was formulated by Michael Lynch and goes thus:
- nothing in evolution makes sense except in the light of population genetics
- in prokaryotes, with Ne values on the order of 109, the cost of even a few non-functional nucleotides is high enough to make such useless sequences subject to efficient purifying selection
- hence virtually no junk DNA in prokaryotes
- why have eukaryotes not lost their introns?
- purifying selection in typical populations of multicellular eukaryotes is too weak to weed out individual introns
- null models are standard in physics but apparently not in biology
- if biology is to evolve into a "hard" science, with a solid theoretical core, it must be based on null models
- no other path is known
- most biologists do not pay much attention to population genetic theory
- the time seems to have come for this to change
- with advances in functional genomics, such theory becomes directly relevant for many directions of experimental research
