Invasions by exotic species threaten agriculture, human health, the conservation of native species, and the maintenance of biological diversity. These threats have economic and environmental impacts both within the United States and globally. Attempts to understand the causes of successful invasions are frustrated by the large number of factors that can affect invasion success. This project will combine laboratory experiments and theoretical research to examine how biological diversity and environmental disturbance interact to affect invasion. Deeper insights into these processes will advance applied research as human modifications of the environment increase. The research extends a productive international collaboration and will train early-career US researchers in experimentation, mathematics, and theory. Freshman undergraduate students will be offered a research track that begins with a general course in research methods and is followed by additional seminars and independent research projects. Middle school students from underserved groups will participate in a Higher Achievement Program at Pennsylvania State University; this is a non-profit, academic support program that prepares students to complete high school and be college-ready. Because biodiversity and disturbance frequently interact, their net effects on invasion and invasion resistance are difficult to predict and interpret. Rapid evolution further complicates these interactions and their effects on invasion success. This project will combine experimental manipulations with mathematical models in an iterative approach to study the effect of independent, and combined, manipulation of disturbance and diversity on invasion success; and the role of adaptation to disturbance regimes in mediating invasion resistance. The researchers will independently manipulate disturbance frequency and intensity, and bacterial diversity, in a factorial design to assess the role that these factors (and their interactions) play in invasion resistance. They will also assess the hypothesized importance of adaptation to disturbance regimes by assessing invasion success following changes to previously established regimes. Laboratory microbial experiments will generate rapid results, allow iterative model improvement, and provide ideal opportunities to test rapid evolution. This combination surpasses research that could be accomplished with natural communities and promises to develop general ecological theory relevant to diverse, natural communities. The research will extend a nascent international collaboration by engaging two researchers with complementary expertise, one in modeling and the second in experimentation.