Evolution of Functional Genomic Diversity During a Bottleneck.

Area of Science:

• Evolutionary genetics
• Population genetics
• Genomics

Background:

• Population bottlenecks and range expansions significantly impact species' genetic diversity.
• Neutral variants can fix during these events, mimicking selective sweeps.
• Previous studies focused on neutral variants, leaving the dynamics of deleterious variants less explored.

Purpose of the Study:

• To investigate the dynamics of genomic diversity in functional regions with deleterious variants during bottlenecks and range expansions.
• To determine how the dominance of deleterious mutations affects diversity patterns.
• To compare diversity levels in regions with deleterious mutations versus neutral regions.

Main Methods:

• Modeling range expansions as serial founder effects.
• Analyzing the formation and properties of diversity troughs in regions with deleterious mutations.
• Varying the dominance level of deleterious mutations (co-dominant, recessive, partially recessive).
• Considering the influence of recombination rates and selection coefficients.

Main Results:

• Functional regions with deleterious variants can form diversity troughs similar to selective sweeps.
• The number of troughs increases more rapidly with co-dominant than recessive deleterious mutations.
• Genetic diversity declines slower in regions with partially recessive mutations compared to co-dominant or neutral regions.
• These effects are more pronounced in low-recombination regions and with intermediate selection coefficients.

Conclusions:

• Deleterious mutations, particularly partially recessive ones, can shape genomic diversity patterns during population size changes.
• Functional, low-recombination regions may act as reservoirs of genetic diversity during range expansions if most deleterious mutations are partially recessive.
• Understanding these dynamics is crucial for predicting evolutionary trajectories and conserving genetic diversity.