A Nonlinear Dynamics Framework for Mutation-Selection Balance Reveals Dominance-Dependent Bistability in Auto- and Allotetraploids

Dominant alleles with biased mutation rates in tetraploid mutation-selection balance show two bistable equilibrium points, with a wide selection-coefficient range in autotetraploids versus a narrow range in diploids.

• Why it matters: Population genetics theory for polyploids is not well developed, limiting understanding of polyploid evolution and crop improvement under increasing environmental stress.
• What they did: The authors built deterministic ordinary-differential-equation models for tetraploids with polysomic (autotetraploid) and disomic (allotetraploid) inheritance and arbitrary dominance, then analyzed mutation-selection balance and used discrete-time simulations for temporal dynamics.
• The result: Bistability and bifurcations fundamentally alter allele-frequency and load dynamics over time, and overdominant mutations yield a distinct equilibrium structure with bistable equilibria only in the allotetraploid model.