Gene-dense autosomal chromosomes show evidence for increased selection

Area of Science:

• Human population genetics
• Evolutionary biology
• Genomics

Background:

• Purifying selection reduces genetic diversity and increases linkage disequilibrium.
• Detecting selection is challenging due to variable recombination rates.
• Effective bottleneck time normalizes for recombination rate variability.

Purpose of the Study:

• To investigate the relationship between gene density and purifying selection across human autosomes.
• To compare signatures of selection in Sub-Saharan African and European populations.

Main Methods:

• Utilized whole genome sequence data from four human populations (one European, three Sub-Saharan African).
• Calculated effective bottleneck time by comparing linkage disequilibrium and genetic maps.
• Correlated effective bottleneck time with autosomal gene density and essential gene density.

Main Results:

• Found strong correlations between high gene density and reduced effective bottleneck time in African autosomes.
• Identified a significant relationship between effective bottleneck time and essential gene density (p=0.006).
• Observed a ~17-21% reduction in effective bottleneck time for gene-dense autosomes in African populations.

Conclusions:

• Gene-dense autosomes experience stronger purifying selection than gene-poor autosomes.
• Selection efficiency is higher in Sub-Saharan African populations due to larger effective population sizes.
• Highlights the importance of studying selection within diverse human populations.