Geographic population structure in an outcrossing plant invasion after centuries of cultivation and recent founding events

Population structure and genetic diversity of plant invasions are the result of evolutionary processes such as natural selection, drift and founding events. Some invasions are also molded by specific human activities such as selection for cultivars and intentional introduction of desired phenotypes, which can lead to low genetic diversity in the resulting invasion. Dyer’s woad (Isatis tinctoria; Brassicaceae) has been used as a dye source for at least eight centuries in Eurasia. It was introduced to the eastern USA in the 1600s and is now considered invasive in the western USA.

Collection locations of Isatis tinctoria in Eurasia.
Collection locations of Isatis tinctoria in Eurasia. Image credit: Gaskin et al.

A recent study by Gaskin et al. published in AoB PLANTS investigated the genetic diversity and origins of a long-term I. tinctoria cultivar. A genetic analysis of 645 plants from the USA and Eurasia suggests that there were two distinct invasions in western USA that most likely originate from Switzerland, Ukraine and Germany, which correlates with initial biological control agent survey findings. Genetic information on population structure, diversity and origins assists in efforts to control invasive species, and continued combination of ecological and molecular analyses will help bring us closer to sustainable management of plant invasions.