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Greater Yellowstone Ecosystem Report

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Introduced, non-native predators often impact native species and ecosystems. These effects can be particularly devastating to native organisms because they are often naïve to the effects of non-native predators (Park 2004, Lockwood et al. 2007). Interestingly, naïve prey are more common in freshwater than in terrestrial ecosystems (Cox and Lima 2006). For example, introduced predators in lakes have caused local extinctions of native animals (e.g., Brooks and Dodson 1965, Witte et al. 1992) and altered food webs (e.g., Witte et al. 1992; Tronstad, Hall, Koel, in review). Because predators eliminate a prey's fitness, predation is an important selective force. Selection on prey can occur directly on morphology, behavior and life-history traits by altering the mean expression of a trait in a population. Selection on prey can also act indirectly, favoring phenotypic plasticity which ameliorates the effects of predation. Thus, among the many impacts of non-native predators in their introduced range, these animals can alter the morphology, behavior and life-history traits of their prey (e.g., Reznick and Endler 1982, Crowl and Covich 1990, Skelly and Werner 1990, Krist 2002).