Size-dependent Predation Risk in Tadpoles
Open Access
- Author:
- Rosenberg, Danielle Elyse
- Area of Honors:
- Veterinary and Biomedical Sciences
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Tracy Lee Langkilde, Thesis Supervisor
Dr. Lester C Griel Jr., Thesis Honors Advisor - Keywords:
- Prey Response to Predator Cue
Behavior
Tadpoles
Rana Sylvatica
Predation - Abstract:
- Prey often respond to predation risk by changing their behavior, a phenomenon that can have strong impacts on ecosystems. Tadpoles are important components of aquatic ecosystems, and typically respond to predator cues by reducing their activity level. Different predators likely present different levels of risk to tadpoles, and these risks may change as tadpoles grow larger and become faster. As a result, tadpoles should change their activity levels to match the level of risk represented by chemical cues of specific predators. In this study, I measured the feeding rates (or risk) of different predators on small and large wood frog (Rana sylvatica) tadpoles, and tested how tadpoles of each size class responded behaviorally to the cues of these different predators. Eight tadpoles from each size class were placed into controlled environments with different predators (newts, dragonfly larvae, backswimmers, and predaceous diving beetles). These predators were allowed to feed on the tadpoles for 2 hours, and the number of remaining tadpoles was counted. I found that dragonfly larvae were the most effective predators on tadpoles and that, across all predators, predation rate decreased as tadpole size increased. Next, I examined the behavior of tadpoles when introduced to cues of these various predators. This was conducted by placing eight tadpoles from each size class into a controlled environment with a predator cue, and observing their activity level over 30 minutes. I found that tadpoles decreased their activity level to the same extent regardless of predator cue and the size of the tadpole. This research contributes to our understanding of the predator-prey relationships in these organisms. My results suggest that these tadpoles do not alter their responses depending on predator risk, or they assess the risk of different predators using information not measured in this study (e.g., the number of tadpoles consumed). This research provides useful insight into the workings of aquatic ecosystems and the various effects that predators can have on tadpoles during their various pre-metamorphic stages.