Origin,local experience,and the impact of biotic interactions on native and introduced <Emphasis Type="Italic">Senecio</Emphasis> species

A key gap in understanding the long-term success of invasive species is how biotic interactions change with the duration of experience in the introduced range. We examined biotic interactions using a common garden experiment with native, hybrid, and exotic Senecio species representing a range of experience in the UK. Introduced species had fewer aphids and pathogens and more root colonization by mycorrhizal fungi compared to natives; hybrids generally had intermediate levels of interactions. The duration of experience in the introduced range was reflected by an increasing degree of variability in enemy release. These findings support the enemy release hypothesis and indicate the potential for changes in enemy release as time and experience in the new range increase.