Deleterious mutations as an evolutionary factor. II. Facultative apomixis and selfing.

Area of Science:

• Evolutionary biology
• Population genetics

Background:

• Deleterious mutations accumulate in genomes, posing a threat to species survival.
• Reproductive strategies like sexual reproduction (amphimixis) and asexual reproduction (apomixis/selfing) have different evolutionary advantages.

Purpose of the Study:

• To investigate how truncation selection against deleterious mutations influences the evolution of reproductive modes.
• To determine the conditions under which sexual reproduction is favored over asexual reproduction.

Main Methods:

• Mathematical modeling of populations with deleterious mutations and varying reproductive strategies.
• Analysis of genome degradation rate (v) and its impact on reproductive mode evolution.
• Examination of mutation load (u) and critical mutation number (k) effects.

Main Results:

• A genome degradation rate (v) above 1.25 favors obligate amphimixis (sexual reproduction).
• Below this threshold, selection favors asexual reproduction, with resource allocation to seeds increasing.
• Selection outcomes for outcrossing vs. selfing depend on mutation load, critical number, and recessivity.

Conclusions:

• Truncation selection can be a significant factor promoting sexual reproduction, counteracting the inherent advantages of asexual reproduction.
• The evolution of reproductive strategies is complex, influenced by mutation rates, selection pressures, and genetic factors.