Genealogy-dependent variation in viability among self-incompatibility genotypes

Area of Science:

• Plant reproductive biology
• Population genetics
• Evolutionary genetics

Background:

• Many hermaphroditic plants self-incompatibilize via the S-locus, which controls pistil and pollen specificity.
• High polymorphism at the S-locus maintains numerous specificities within plant species.
• Empirical studies observe unusual patterns in S-allele genealogies.

Purpose of the Study:

• To investigate the conjecture that linked recessive deleterious factors reduce zygote viability between related S-alleles.
• To model the evolutionary dynamics of S-locus polymorphism under viability selection and genealogical antagonism.

Main Methods:

• Developed diffusion approximation models to simulate S-locus evolution.
• Incorporated variation in zygote viability among S-locus genotypes.
• Modeled antagonistic interactions between new and parent S-allele specificities.

Main Results:

• Variation in viability tends to decrease the number of S-specificities maintained in a population.
• Genealogy-based antagonism slows the rate at which S-allele lineages diverge (bifurcate).

Conclusions:

• Linked deleterious factors can explain reduced viability between related S-alleles.
• These genetic mechanisms may contribute to observed patterns in S-allele genealogies.
• The findings offer insights into the maintenance of S-locus polymorphism and plant reproductive strategies.