Single-locus polymorphism in a heterogeneous two-deme model.

Area of Science:

• Evolutionary biology
• Population genetics
• Ecological genetics

Background:

• Environmental heterogeneity is a key factor proposed to explain high genetic variation in natural populations.
• Previous theoretical models often used simplified scenarios (e.g., two alleles, fixed gene flow) to study this effect.
• The impact of spatial heterogeneity on genetic variation with complex parameters remains less understood.

Purpose of the Study:

• To compare the capacity of single-deme versus two-deme models to maintain genetic variation under environmental heterogeneity.
• To investigate the influence of multiple alleles, random selection schemes, and varying gene flow levels.
• To analyze equilibrium allele-frequency patterns and their prevalence.

Main Methods:

• Comparative analysis of single-deme and two-deme population genetics models.
• Inclusion of multiple alleles, random selection schemes, and diverse migration rates.
• Examination of fitness space volumes supporting genetic variation and equilibrium allele frequencies.

Main Results:

• The two-deme model maintains genetic variation across significantly larger volumes of the fitness space compared to the single-deme model.
• This effect is particularly pronounced when heterozygote fitness is lower.
• Equilibrium allele-frequency patterns in the two-deme model are more diverse and show a strong dependence on gene flow.

Conclusions:

• Spatial heterogeneity, as modeled by a two-deme system, is more effective at maintaining genetic variation than previously assumed.
• Broader ranges of selection schemes can sustain variation in heterogeneous environments.
• Gene flow plays a critical role in shaping allele frequencies and maintaining diversity in spatially structured populations.