My master’s project investigates the ecological impact and potential for rapid adaptation of invasive trout in the alpine lakes of the Wind River Range in Wyoming. Beginning several decades ago, non-native trout (i.e. Golden Trout and Cutthroat Trout) were stocked in multiple high elevation lakes of the Wind River Range (Wiley, 2003). Since the introduction of these fish, some of these lakes have existed as self-sustaining fisheries while others have been periodically or recently stocked for recreation (Wiley, 2003). This distinct history of stocking events, the presence of multiple trout species, and the existence of comparable fish and fishless lakes allows for a fascinating system in which to examine the tempo of ecological and evolutionary change that may result from the introduction of a novel invasive predator. Preliminary data in our system suggests that trout predation on naturally occurring zooplankton has driven a decrease in zooplankton body size in Wind River alpine lake zooplankton communities (Boyle et al., unpublished data). Since fish are expected to selectively consume only large, easily visible zooplankton, their predation is thought to have caused the observed increase in the abundance of small zooplankton species (Boyle et al., unpublished data). Furthermore, since trout rely on the spacing between their gill rakers to sieve plankton, average gill raker spacing must decrease in proportion to plankton size in order for fish to continue to successfully prey on zooplankton as their sizes decrease (Wright et al., 1983; Gibson, 1988). Therefore, I am investigating the hypothesis that selective predation pressure on zooplankton may in turn drive the rapid evolution of trout gill raker morphology. I expect to find (1) a decrease in gill raker spacing, (2) an increase in gill raker number, or (3) both. Although rapid evolution of gill rakers is known from other fish systems (e.g. alewives, whitefish—Palkovacs et al., 2014; Kahilainen et al., 2011) these dynamics have never been investigated in trout.