Modern Synthetic Theory

The Modern Synthetic Theory, developed by Sewall Wright, R.A. Fisher, Ernst Mayr, Julian Huxley, Theodosius Dobzhansky, George Gaylord Simpson and Ernst Haeckel, reinterprets natural selection using post-Darwinian genetic discoveries, and identifies five basic factors that together drive organic evolution. (i) Gene mutation (point mutation) — a change in the structure of a single gene, which can alter phenotype and produce heritable variation. (ii) Chromosomal mutation — a structural change to a whole chromosome via deletion, addition/duplication, inversion or translocation, which likewise alters phenotype and produces variation. (iii) Genetic recombination — new allele combinations arising from crossing-over during meiosis, generating heritable genetic variation within a species without any new mutation being required. (iv) Natural selection — while it does not itself create genetic variation, it acts as the driving force of evolution by favouring some of the variants that mutation and recombination generate while rejecting others. (v) Reproductive isolation — barriers tha …