evolution & genetics - senecio7の日記

Charlesworth B & Charlesworth D 2009 Darwin and genetics. Genetics 183:757-766.

Mendel's ability to solve the most difficult problem in 19th century biology after the mechanism of evolution rests on his use of a then-unique approach
combining rigorous genetic experiments with quantitative, probabilistic predictions about their expected outcomes
in other words, using biological data to test a quantitative hypothesis
it is a triumph of productive theoretical reasoning that Mendel proposed his particulate inheritance hypothesis well before a proper understanding of the cellular basis of sexual reproduction was achieved by either animal or plant biologists

ironically, Darwin analyzed data from his own crossing experiments on distyly in Primula species (summarized in Darwin 1877, chap. 5)
which gave what we can now see as clear evidence for Mendelian ratios

blending inheritance leads to a difficulty that was forcefully pointed out by Fleeming Jenkin
the professor of engineering at the University of Edinburgh
the building next to ours is, somewhat unfortunately perhaps, named after him

Darwin himself had the idea of selective neutrality:
variations neither useful nor injurious would not be affected by natural selection, and would be left a fluctuating element, as perhaps we see in the species called polymorphic (Darwin 1859, p. 81)

another way in which modern evolutionary studies have contributed to genetics, as opposed to genetics contributing to evolutionary biology, is that an interest in quantifying the extent of genetic variation [initially motivated by a debate about whether variation within species is largely composed of recent mutations or includes a considerable proportion of variants maintained by balancing selection (Dobzhansky 1955; Lewontin 1974)] ultimately led to the discovery of vast numbers of DNA sequence variants that can be used as genetic markers for mapping
although these data did not in themselves settle the debate about whether selection maintains variation

the study of the population genetics of multi-locus systems once appeared to be an esoteric field
remote from empirical data
which contributed to the reputation of theoretical population genetics for dryness and irrelevance to biology
nevertheless, very important principles were developed that are now widely used by other geneticists
including ways to measure linkage disequilibrium

from being a major headache for early supporters of evolution, genetics paved the way for models of evolution based on the known properties of inheritance
the constraints experienced by genes and genomes in evolution were correctly incorporated into quantitative models
new possibilities, unknown to Darwin, were discovered