Allele frequency dynamics in a pedigreed natural population

Area of Science:

• Population genetics
• Evolutionary biology
• Genomics

Background:

• Population genetics aims to understand how genetic drift, natural selection, and gene flow influence allele frequencies.
• Quantifying the underlying processes like variation in survival, reproduction, and movement is challenging.
• A population pedigree, detailing relationships among individuals over time, is crucial for a complete understanding.

Purpose of the Study:

• To directly characterize the roles of evolutionary processes in shaping genetic variation over time.
• To utilize extensive pedigree and genomic data from Florida Scrub-Jays (Aphelocoma coerulescens).
• To model genetic drift and estimate individual contributions to the population.

Main Methods:

• Gene dropping simulations to estimate individual genetic contributions.
• Modeling genetic drift on a known population pedigree.
• Analyzing allele frequency changes in relation to survival, reproduction, and gene flow.
• Utilizing models that account for population size changes.

Main Results:

• Observed allele frequency changes are largely predictable by accounting for founder genetic contributions.
• Recent immigrants significantly contribute to genetic variation, with gene flow explaining some shifts initially attributed to selection.
• A few single nucleotide polymorphisms (SNPs) showed evidence of short-term directional selection after accounting for gene flow.
• Variation in survival and reproductive success were the primary drivers of allele frequency changes, with gene flow playing a lesser role.

Conclusions:

• Population pedigrees and genomic data provide a comprehensive view of short-term evolutionary dynamics.
• Gene flow can be a substantial driver of allele frequency shifts in natural populations.
• Individual variation in survival and reproduction are key factors in shaping genetic variation over time.