Polygenic local adaptation in metapopulations: A stochastic eco-evolutionary model

Area of Science:

• Evolutionary biology
• Population genetics
• Ecology

Background:

• Metapopulations with islands face challenges of local adaptation.
• Hard selection models link population size to local fitness.
• Habitat-specific selection acts on additive traits.

Purpose of the Study:

• Analyze conditions for local adaptation in a metapopulation under hard selection.
• Investigate the impact of polygenic traits and habitat rarity on adaptation.
• Assess the role of genetic drift and demographic stochasticity.

Main Methods:

• Utilized diffusion approximation for metapopulation analysis.
• Modeled hard selection with habitat-dependent directional selection.
• Accounted for genetic drift and demographic stochasticity, neglecting linkage disequilibria.

Main Results:

• Local adaptation is more restricted for polygenic traits in rare habitats.
• Moderate migration load can decrease population sizes, increasing drift.
• Demographic stochasticity amplifies population decline and collapse risk.

Conclusions:

• Hard selection imposes stricter adaptation limits for complex traits in rare environments.
• Positive feedback exists between maladaptation and population decline.
• Demographic stochasticity significantly increases extinction risk in rare habitats.