The evolution of tandem repeat sequences under partial selfing and different modes of selection

Area of Science:

• Genetics
• Evolutionary Biology
• Population Genetics

Background:

• Tandem repeat (TR) sequences are crucial sources of genetic variation.
• Previous population genetic models primarily focused on large, randomly mating, haploid populations.
• Selfing (partial self-fertilization) increases homozygosity, potentially altering TR evolution.

Purpose of the Study:

• To investigate the evolution of homologous TR sequences in partially selfing, diploid populations.
• To analyze TR evolution under four distinct selective regimes relevant to TRs.
• To understand the influence of mating systems on TR sequence variation.

Main Methods:

• Mathematical modeling to simulate TR evolution.
• Computer simulations of diploid populations with partial selfing.
• Analysis across four selective regimes: additive purifying, truncation-like purifying, heterozygote disadvantage, and stabilizing selection.

Main Results:

• Selfing primarily increases homozygosity, enhancing variation from unequal recombination within individuals.
• Selfing also increases genetic variation between individuals.
• Selection on TRs becomes more effective under partial selfing, reducing genetic load despite increased drift.

Conclusions:

• Mating systems, particularly selfing and inbreeding, are critical factors influencing TR sequence variation.
• Selfing alters the evolutionary dynamics of TRs by modifying homozygosity levels.
• The effectiveness of selection on TRs is enhanced in partially selfing populations.