Phenotypic and genotypic parallel evolution in parapatric ecotypes of Senecio

The independent and repeated adaptation of populations to similar environments often results in the evolution of similar forms. This phenomenon creates a strong correlation between phenotype and environment and is referred to as parallel evolution. However, we are still largely unaware of the dynamics of parallel evolution, as well as the interplay between phenotype and genotype within natural systems. Here, we examined phenotypic and genotypic parallel evolution in multiple parapatric Dune-Headland coastal ecotypes of an Australian wildflower, Senecio lautus. We observed a clear trait-environment association in the system, with all replicate populations having evolved along the same phenotypic evolutionary trajectory. Similar phenotypes have arisen via mutational changes occurring in different genes, although many share the same biological functions. Our results shed light on how replicated adaptation manifests at the phenotypic and genotypic levels within populations, and highlight S. lautus as one of the most striking cases of phenotypic parallel evolution in nature.

Automated summary

The independent and repeated adaptation of populations to similar environments often leads to the evolution of similar forms, known as parallel evolution. This study on multiple coastal ecotypes of Senecio lautus in Australia shows a strong correlation between phenotype and environment, with all populations evolving along the same phenotypic trajectory through mutational changes in different genes. The research sheds light on replicated adaptation at both phenotypic and genotypic levels within populations, highlighting S. lautus as a striking example of phenotypic parallel evolution in nature.