Density-dependent selection incorporating intraspecific competition. II. A diploid model

Area of Science:

• Population Genetics
• Evolutionary Biology
• Mathematical Biology

Background:

• Density-regulated selection is crucial for understanding population dynamics and evolution.
• Intraspecific competition influences genotype fitness and population stability.
• Previous models often focused on purely density-dependent selection, potentially overlooking complex interactions.

Purpose of the Study:

• To introduce and analyze a diploid model incorporating intraspecific competition within density-regulated selection.
• To investigate how genotypic differences in carrying capacity and competition sensitivity affect fitness and genetic variation.
• To explore the conditions for maintaining genetic variation and population stability under these competitive dynamics.

Main Methods:

• Development of a diploid mathematical model for density-regulated selection.
• Incorporation of genotype-specific carrying capacities and sensitivity to intraspecific competition.
• Analysis of fitness functions that are both density and frequency dependent.
• Numerical studies to confirm theoretical predictions regarding equilibria and stability.

Main Results:

• Fitness is determined by a balance between carrying capacity and sensitivity to intraspecific competition.
• Intergenotypic interactions facilitate the maintenance of genetic variation more effectively than purely density-dependent selection.
• Multiple interior equilibria are possible, and stability does not require overdominance or specific carrying capacities.

Conclusions:

• Intraspecific competition, when modeled with genotype-specific parameters, can be a significant driver for maintaining genetic diversity.
• The findings challenge the necessity of overdominance for stable genetic variation in density-regulated populations.
• The study provides insights into population size regulation and optimization principles in evolutionary contexts.