Abstract
How do complex biological systems reconcile conflicting selection pressures acting on their components? We study this question in the context of the collaborative non-self recognition selfincompatibility, a system that inhibits self-fertilization in plants. Self-incompatibility relies on specific molecular recognition between proteins, expressed in female and male reproductive organs. These proteins co-evolved to enable fertilization between individuals and disable self-fertilization simultaneously. We study the impact of these opposing selection pressures on the amino acid frequencies in these proteins’ recognition domain. We construct a theoretical framework enabling promiscuous recognition between proteins and multiple partners each, as found empirically, and employ stochastic simulations. We find asymmetric responses to selection affecting mostly the female, but not the male protein composition. Using large deviations theory, we well-approximate the simulated frequencies and find agreement with genomic data. We expect our methodology to be broadly applicable to analyze the balance between conflicting pressures in additional biological systems.
Competing Interest Statement
The authors have declared no competing interest.
