Parallel functional differentiation of an invasive annual plant on two continents

Broadly distributed species encompass populations spread across habitats that vary in their climatic, edaphic and biotic environmental characteristics. The success of broadly distributed species across a wide range of environmental conditions is, in part, determined by their ability to maintain fitness and positive population growth rates across the range of local environmental conditions encountered by individual populations. Rapid local adaptation frequently occurs during the spread of invading species. It remains unclear, however, how consistent, and therefore potentially predictable, such patterns of local adaptation are.

In a recent article published in AoBP, Latimer et al. addressed this question in the invasive annual plant Erodium cicutarium (redstem storksbill). Originally from Europe, E. cicutarium spread across both North and South America. The plant grows in diverse habitats from deserts to mountaintops. The question is, has it evolved to grow differently in different habitats during these invasions, and do such differences help it spread? By experimentally growing seeds from many sites in California and Chile, Latimer et al. discovered strong local genetic differences: plants from dry areas “live fast and die young,” flowering weeks earlier than plants from wetter areas. Patterns of local differences among Chilean populations matched those in California, suggesting this species evolves in predictable ways as it spreads.