The distribution of plant and animal species may change due to both natural causes, or due to human-assisted introductions to new areas. This research uses a large global database that documents the occurrence of mammals and their parasites to determine the kinds of parasites that are gained and lost by different species as they are introduced to new areas. This study explores how environmental factors and the traits of parasites (how they are transmitted or whether they specialize on a host) may explain whether they are retained, lost, or newly acquired. This study will allow researchers to anticipate new associations between parasites and host species, which is important to conservation science, public health, and the food industry. This research program will train undergraduate and graduate students and school teachers in the use of existing databases and computational software for addressing pressing ecological questions.The goal of this study is to use the Global Mammal Parasite Database and other data sources to examine the association of mammals and their parasitic hosts following their introductions into novel geographic areas. Statistical and modeling approaches to disentangle the role of climatic similarity, phylogenetic compatibility, and parasite traits (transmission mode, level of specialization and prevalence) will be developed to explain the loss and gain of parasites by introduced mammals. This work addresses a fundamental question in community and disease ecology by exploring the factors that promote the intimate associations between species pairs. Given the geographic scope of this study and breadth of introductions examined, the results of this research will provide a global context for assessing the risk of emerging infectious diseases of animals and humans due to the redistribution of introduced hosts and their parasites.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.