RISK OF POPULATION EXTINCTION FROM FIXATION OF NEW DELETERIOUS MUTATIONS.

Area of Science:

• Population Genetics
• Evolutionary Biology
• Genomics

Background:

• Deleterious mutations can impact population fitness and survival.
• The role of mildly deleterious mutations in extinction risk is a key concern in evolutionary studies.

Purpose of the Study:

• To analyze the fixation of new deleterious mutations in a constant-size, randomly mating population.
• To determine the impact of mutation characteristics on extinction risk.

Main Methods:

• Mathematical modeling of mutation fixation and extinction time.
• Analysis of selection coefficients (s) and their distributions (gamma, exponential).
• Consideration of population effective size (Ne).

Main Results:

• Mildly deleterious mutations are more critical for extinction than lethal ones in larger populations.
• Extinction time is minimized when selection coefficient s ≈ 0.4/Ne.
• Increased variance in selection coefficients can alter extinction risk depending on the mean selection coefficient.

Conclusions:

• Nearly neutral mutations present the greatest extinction risk for stable populations.
• Even populations with effective sizes around 10^3 may face significant extinction risk from new mutations.
• Understanding mutation dynamics is crucial for predicting long-term population viability.