The modern synthesis
Field · 1918-1950, Britain and the United States · Biology, stage 2: Map the fields
The modern synthesis is the reconciliation of Darwinian selection with Mendelian genetics. For two decades after 1900 the two looked incompatible: genetics dealt in discrete jumps, selection in gradual change. Fisher, Haldane, and Wright showed mathematically that selection acting on many small-effect genes in a population produces exactly the gradual change Darwin described, and Dobzhansky and Mayr then carried the mathematics into field and laboratory work on real species.
What it claims
- Evolution is change in allele frequencies within populations.
- Mendelian inheritance and gradual Darwinian change are consistent once many genes of small effect are assumed.
- Selection, drift, mutation, and migration are jointly sufficient to account for evolutionary change; no additional directing force is required.
- Speciation happens when populations become reproductively isolated, usually after geographic separation.
Key ideas
People
Sources
- Modern synthesis (20th century) Wikipedia
- Population Genetics Stanford Encyclopedia of Philosophy
- Population genetics Wikipedia
