History

Directional hypothesis vs Balancing hypothesis

• deletorious / advantageous genes

↓

Neutral hypothesis

• deletorious (50%) / neutral (45%) / advantageous genes (5%)

• Challenge in theoretical prediction 

1. 進化速度が、霊長類と齧歯類で同じ？

2. 多様性は、人類とE. coli で同じ？

↓

↓ (+ Selection ~ Population size)

↓

Nearly neutral hypothesis

• selected (30%) / nealy neutral (30%) / neutral (40%) genes

• Assumption

1. | Effective population size × selectionstrength | < 1

↓

Welcome to molecular population genetics

• First empirical data of DNA polymorphism (Kreiman, 1983, Nature)

• Factors shaping DNA polymorphism

  • Mutation

  • Random genetic drift

  • Demographic history

  • Selection

  • Recombination

• Coalescent theory (Backward in time)

  • Kingman (1982)

  • Sample-based theory

  • Simple algorythm of simulation

↓

Test of neutrality

• Tajima's D

↓

"Population" genetics (beyond single-gene-based genetics)

• Focusing multi-locus -> Distinguishing selection & demography

• Sweeping selection causes "hitchhiking (mutation spreads before recombination)"

↓

Polymorphism in genomic scale

• Biallelic coalescence with Hitchhiking & Background selection

• Coalescence in a structured population

Coalescent theory

• Concept

• With recombination

Reference

• Directional hypothesis

• Balancing hypothesis

• Neutral hypothesis

1. https://www.nig.ac.jp/museum/evolution-x/01_c.html

• Nearly neutral hypothesis

1. Ohta (1972) "Population size and rate of evolution", J. Mol. Evol.

2. Ohta (1972)  Nature

3. Ohta (1974) Nature