INBREEDING DEPRESSION UNDER JOINT SELFING, OUTCROSSING, AND ASEXUALITY.

Area of Science:

• Evolutionary Biology
• Population Genetics
• Reproductive Strategies

Background:

• Inbreeding depression, caused by deleterious mutations, poses a significant challenge to the long-term viability of partially selfing populations.
• Asexual reproduction can alter the dynamics of mutation accumulation and purging, potentially impacting inbreeding depression.

Purpose of the Study:

• To investigate the effects of partial asexual reproduction on inbreeding depression in populations with nearly recessive lethal mutations.
• To model how varying frequencies of asexuality, selfing, and outcrossing influence mutation load and purging efficiency.

Main Methods:

• Developed a population genetic model incorporating partial asexual reproduction alongside selfing and outcrossing.
• Analyzed scenarios with constant reproductive frequencies and cyclical patterns of sexual and asexual generations.
• Examined the interplay between mutation rates, selfing rates, and the degree of asexuality.

Main Results:

• Increased levels of asexuality generally led to higher equilibrium inbreeding depression for a given selfing rate.
• This effect is attributed to a reduced proportion of sexual generations available for purging mutations through selfing.
• Conversely, at very high genomic mutation rates, asexuality decreased inbreeding depression by improving selection against heterozygous mutations.

Conclusions:

• Partial asexual reproduction can exacerbate inbreeding depression in partially selfing populations by limiting purging opportunities.
• The impact of asexuality on inbreeding depression is contingent on the genomic mutation rate.
• Asexuality's role in modulating inbreeding depression is complex, with potential benefits at extremely high mutation rates due to enhanced selection.