The Temporal Dynamics of Background Selection in Nonequilibrium Populations

Area of Science:

• Population Genetics
• Evolutionary Biology
• Genomics

Background:

• Neutral genetic diversity is shaped by mutation, demography, and natural selection.
• Natural selection's effects extend to linked neutral sites via genetic hitchhiking and background selection (BGS).
• Previous studies on joint demography and selection effects yielded contradictory findings.

Purpose of the Study:

• To investigate the interplay between population demography and background selection (BGS).
• To understand the temporal dynamics of neutral genetic diversity under BGS in nonequilibrium populations.

Main Methods:

• Conducted extensive forward simulations of background selection (BGS).
• Utilized a range of demographic models to simulate population histories.
• Analyzed the temporal dynamics of neutral genetic diversity in simulated populations.

Main Results:

• Relative neutral diversity levels in BGS and neutral regions fluctuate over time.
• Initial diversity dynamics following population size changes often oppose long-term trends.
• Classical BGS models are inadequate for predicting diversity in populations not at demographic equilibrium.

Conclusions:

• The temporal dynamics of neutral diversity are crucial for understanding BGS effects.
• Non-equilibrium population histories significantly alter patterns of genetic diversity.
• Reconciles previously contradictory empirical observations on BGS and demography.