Increasingly, species are being found in new locations. In some cases the new species have no demonstrable effect on the habitat. However, there are many cases where invasive species have changed entire ecosystems, such as the defoliation of an entire forest by gypsy moths. We will address the causes and consequences of species invasions by exploring the primary literature. Questions will include: Why are some introduced species invasive whereas others are not? What are the consequences for native species, and how may invasive species be controlled? (BIOL 0140; and one other 0200- or 0300- level biology course) 3 hrs sem.