The Modern Synthesis

The Modern Synthesis

• The modern synthesis combined two important theories in biology
• Darwinian evolution and natural selection
• Mendel's theory of inheritance

Fisher and Haldane (1918-1930)

• Fisher in 1918 described how variation could result from discrete genetic loci
• Haldane in 1920 provided real world examples based in math
• Occurs faster than thought Example: Pepper moths in the industrial revolution

Wright (1932)

• Demonstrated how combinations of genes interacted to produce phenotypes
• Introduced adaptive fitness landscapes
• combinations of genes can produce optimum trait values
• Investigated how small populations were at risk of inbreeding depression
• Increased chance of genetic drift

Dobzhansky (1937)

• Described natural populations by new mathematics
• Was easier to understand
• Natural populations had lots of standing variation
• Introduced Chromosomes
• Some regions are linked to each other
• Identified main sources of evolutionary change
• Mutations
• Chromosome rearrangement
• Multi-gene effects during development
• Polyploidy: gene duplication

Huxley (1942)

• Coined the term "Modern Synthesis"
• Helped to popularize
• Provided many examples to convince the public

Mayr (1942)

• Examined how population variation led to speciation
• Described allopatric speciation
• When two populations are divided, evolve and become separate species
• Defined the Biological Species Concept
• A group of interbreeding populations that do not breed with others

Conclusion

• Together these researchers built the fundamentals of quantitative biology. Taking disconnected parts of biology and wrapping them together using verifiable mathematics. These founding individuals brought biology into the modern age.