Genetic drift in an infinite population. The pseudohitchhiking model

Area of Science:

• Population genetics
• Evolutionary biology
• Molecular evolution

Background:

• Linked selection can induce stochastic dynamics at neutral loci.
• The pseudohitchhiking model approximates these effects.
• Diffusion theory is inadequate for rapid allele frequency changes.

Purpose of the Study:

• To present a one-locus model for linked selection effects.
• To analyze neutral dynamics using continuous-time Markov processes.
• To investigate the coalescent properties and frequency spectrum of the pseudohitchhiking model.

Main Methods:

• Utilizing the theory of continuous-time Markov processes with discontinuous sample paths.
• Developing a stationary distribution for the pseudohitchhiking model.
• Analyzing substitution processes and coalescent properties.

Main Results:

• The pseudohitchhiking model captures effects of linked selection.
• The model's coalescent exhibits a random number of branches at each node.
• This leads to a frequency spectrum distinct from the equilibrium neutral model.

Conclusions:

• Genetic draft, induced by linked selection, can be a significant evolutionary force.
• The pseudohitchhiking model provides a framework for studying these dynamics.
• Considering genetic draft may resolve long-standing paradoxes in population genetics.