The roads most traveled: genetic convergence in plant repeated evolution

Traits are well-known to recur during evolution, yet how broadly predictable this is at the genetic level remains unresolved. Here, I highlight recent work in plants to underscore that genotype-phenotype repeatability at the level of homologous genes is influenced by mutational effect stability, the extent to which mutations generate consistent phenotypic outcomes across lineages. I propose that observing loss-of-function mutations underlying trait evolution in one lineage increases the likelihood that homologous genes will be reused in convergent evolution across other lineages, whereas observing gain-of-function mutations often indicates reduced predictability at the homolog level. These patterns provide a framework for predicting when evolution will follow homologous genetic routes over long evolutionary timescales.