Collective enforcement of S-RNase-based self-incompatibility

Area of Science:

• Evolutionary biology
• Plant reproductive genetics
• Molecular evolution

Background:

• Previous models focused on the evolution of self-incompatibilities.
• The origin of nonself-incompatibilities, crucial for understanding mating system evolution, remains less explored.
• Self-incompatibility (SI) and self-compatibility (SC) systems significantly impact plant population genetics and evolution.

Purpose of the Study:

• To present a novel model explaining the evolutionary origin of new nonself-incompatibilities.
• To investigate the interplay between S-RNase mutations and SLF repertoire evolution in shaping mating system dynamics.
• To elucidate the selective pressures driving the balance between SI and SC haplotypes.

Main Methods:

• Theoretical modeling of evolutionary dynamics.
• Analysis of selection pressures on S-RNase and SLF genes.
• Simulation of haplotype frequency changes under different evolutionary scenarios.

Main Results:

• Natural selection favors S-RNase mutations that create nonself-incompatibilities with SC haplotypes, allowing SI haplotypes to avoid inbreeding costs.
• The generation of nonself-incompatibilities is counteracted by selection on SLF repertoires, promoting compatibility.
• The model predicts a dynamic balance between forces favoring new compatibilities and those generating new nonself-incompatibilities.

Conclusions:

• The evolution of mating systems is driven by a fluctuating balance between selection for new compatibilities and 'mutational adjustment' of S-RNases.
• This balance determines the relative frequencies of SI and SC haplotypes over evolutionary time.
• The model provides a framework for understanding the maintenance and breakdown of self-incompatibility.