Seasonal models reveal niche changes during invasion in Capsella bursa-pastoris

Researchers often use ecological niche models to predict where species might establish and persist under future or novel climate conditions. However, these predictive methods assume species have stable niches across time and space. Furthermore, ignoring the time of occurrence data can obscure important information about species reproduction and ultimately fitness. In this study, we generate full-year and monthly ecological niche models for Capsella bursa-pastoris to see if we can detect changes in the seasonal niche of the species after long-distance dispersal. We find full-year ecological niche models have low transferability across continents and there are continental differences in the climate conditions that influence the distribution of C. bursa-pastoris . Monthly models have greater predictive accuracy than full-year models in cooler seasons, but the inability of any model to predict summer occurrence in North America suggests a change in the seasonal niche from the native range to the non-native range. These results highlight the utility of ecological niche models at finer temporal scales in predicting species distributions and unmasking subtle patterns of evolution.