Antipredator behavior of chytridiomycosis-infected northern leopard frog (Rana pip/ens) tadpoles

摘要

We investigated the effects of Batmchochytrium dendrobatidis Longcore, Fessier & Nichols, a pathogen implicated in global amphibian population declines, on antipredator behavior of northern leopard fiog (Rana pipiens Schreber, 1782) tadpoles in response to visual and chemical cues of a fish predator, bluegill sunfish (Lepomis macrochims Rafinesque, 1819). We placed infected and uninfected tadpoles in containers partitioned with a transparent divider and measured tadpole activity and distance from thecenter. Infected tadpoles had significantly lower activity levels across all treatments. When exposed to only visual cues, uninfected tadpoles positioned themselves farther from the center divider (and thus the predator) than infected animals. All tadpoles were at similar distances from the center when exposed to chemical cues only, likely because chemical cues alone do not provide spatial information on the location of predators. Infected tadpoles were significantly farther fiom the center divider than uninfected ones when exposed to visual and chemical cues together, suggesting that, although the mechanism is unknown, both cues are necessary to stimulate predator avoidance behavior for infected animals. In a second experiment, infected tadpoles experienced lower mortality than uninfected ones in the lethal presence of fish. Thus, effects of infection on behavioral antipredator responses are complex, but lower host susceptibility to prédation, low activity, and greater distance from predators whenboth chemical and visual predator cues are present likely benefits B dendrobatidis, which relies on host survival for transmission.