Selection in dioecious populations

Area of Science:

• Population Genetics
• Evolutionary Biology
• Quantitative Genetics

Background:

• Analyzing genetic evolution in dioecious (two-sex) populations under weak selection is complex.
• Previous models often simplified dioecious systems or focused on strong selection.
• Understanding how allele frequencies change over generations is crucial for evolutionary studies.

Purpose of the Study:

• To analyze weak selection at a single mutiallelic locus in a dioecious population.
• To determine the conditions under which dioecious populations evolve similarly to monoecious (single-sex) populations.
• To investigate the rate of change in allele frequencies and mean fitness.

Main Methods:

• Mathematical modeling of allele frequency dynamics under weak selection (O(s)).
• Assumptions of random mating (panmixia) and discrete, non-overlapping generations.
• Calculation of equivalent monoecious fitnesses by weighting sex-specific gene contributions.

Main Results:

• Dioecious populations evolve as if monoecious under weak selection (O(s)) after several generations.
• Equivalent monoecious fitnesses require weighting by the number of genes per sex.
• The rate of change in male-female allele frequency differences is O(s2) under specific fitness change conditions.

Conclusions:

• Weak selection simplifies evolutionary dynamics in dioecious populations, mirroring monoecious systems.
• The concept of mean fitness, measured as the genic variance, increases during significant gene frequency change.
• These findings provide a framework for understanding genetic drift and selection in structured populations.