Environmental variation, fluctuating selection and genetic drift in subdivided populations

Area of Science:

• Population Genetics
• Evolutionary Biology
• Theoretical Ecology

Background:

• Extensive research exists on environmental variation's effects on population genetics.
• However, the combined influence of genetic drift and fluctuating selection in structured populations remains poorly understood.

Purpose of the Study:

• To investigate the effects of temporally and spatially varying selection on haploid individuals in subdivided populations.
• To analyze the interplay between genetic drift, fluctuating selection, and population structure.

Main Methods:

• Utilized diffusion theory to model selection dynamics in a large number of demes.
• Employed a perturbation method for analyzing processes with multiple time scales.
• Derived a diffusion approximation for allele frequency changes.

Main Results:

• In the limit of infinite demes, allele frequencies converge to a diffusion process.
• This process mirrors that of a finite, panmictic population under fluctuating selection.
• Coefficients of the diffusion process depend complexly on deme size and migration rate.

Conclusions:

• Demographic parameters like deme size and migration critically influence the balance between dispersive and stabilizing selection.
• These parameters determine whether selection favors alleles with lower or higher fitness variance.
• The study provides insights into the evolutionary dynamics of populations facing environmental heterogeneity and structure.