Developing an Evolutionary Baseline Model for Humans: Jointly Inferring Purifying Selection with Population History

Area of Science:

• Population Genetics
• Genomics
• Evolutionary Biology

Background:

• Establishing baseline models is crucial for understanding population genetics and identifying selection.
• Previous models often overlooked complex genomic processes like background selection and gene conversion.
• The Yoruba population provides a valuable model for studying human evolutionary history.

Purpose of the Study:

• To develop an evolutionarily appropriate baseline model for the Yoruba population.
• To jointly infer selective effects and demographic history.
• To investigate the role of different evolutionary processes in shaping genomic variation.

Main Methods:

• Employed an approximate Bayesian approach for joint inference of selection and demography.
• Utilized the decay of background selection effects around functional elements.
• Incorporated genomic architecture, including recombination rate heterogeneity and gene conversion.

Main Results:

• Inferred a recent 6-fold population growth in the Yoruba population.
• Determined a distribution of fitness effects skewed towards effectively neutral mutations.
• Found that strong or frequent positive selection is inconsistent with the observed data.

Conclusions:

• The developed baseline model accurately reflects evolutionary processes in the Yoruba.
• Weak to moderate positive selection may be occurring but is difficult to detect.
• The findings contribute to a better understanding of human evolutionary genetics and selection.