Maternal Effects of Human-Mediated Disturbances on the Growth and Reproductive Traits of Different Ecotypes of an Annual Invasive Plant Erigeron Annuus

A multifactorial combination of human-mediated disturbances is now recognized as a major driver of the global rise and spread of invasive alien plants. Among the numerous invasive alien plants, annuals have fast adaptability and evolution via maternal effect in human-mediated disturbance environments, such as chemical and physical controls. The characteristic enables them to quickly disperse and establish new habitats. Thus, understanding the adaptability and evolution of invasive plants in response to multifactorial human-mediated disturbances is crucial for developing effective management strategies to control their spread and minimize their impacts on ecosystems and human activities. In order to test the growth and reproductive responses in both the parent and offspring generations, two ecotypes (clump and scatter) of an annual invasive plant, Erigeron annuus, were subjected to simulated trampling, defoliation (simulated herbivory), and herbicide disturbances. We found that disturbances negatively affected the growth and reproduction of E. annuus in parent and offspring generations. In comparison to the scatter ecotype plants, the clump ecotype plants had greater growth and reproductive production, as well as a reduced maternal interference effect to cope with human-mediated disturbances. It enhanced the adaptability of their offspring to disturbances. The findings imply that the evolutionary advantage of clump ecotype plants may explain why they can thrive in disturbed habitats and become invasive in some regions.