Red hue in Tadpole tails decreases based on predator presence
Introduction
Plasticity refers to an organism’s ability to display differential phenotypes according to its environment (Xuea and Leibler 2018). Such capability of change and adaptation allows for many organisms to have higher fitness. Many organism’s physical environments continuously vary due to climate change, which leads to higher temperatures and elevated sea levels. Furthermore, organisms must also display plasticity in the presence of predators for survival. An organism’s change in shape and color is typically linked to predator-induced phenotypic plasticity (Arnett and Kinnison 2017). Predation risk becomes higher if organisms do not adjust to different predatorial signals present in their environment. Adjustment to these signals can be size, as a smaller size could allow an organism to escape quickly or color to decrease predator visibility.
Further, predator-induced phenotypic plasticity has been studied in tadpoles, specifically in Dendropsophus ebaraccatus. Scientists who collected data from tadpoles in ponds near Gamboa, Panama examined the plasticity of tadpoles from shaded environments containing predators and compared them to their study ponds (Touchon and Warkentin 2008). This allowed them to analyze the predator’s likelihood of consuming an egg from a particular environment. Touchon and Warkentin mainly observed the phenotypic differences shown on the tails of the tadpoles, not specific color quantities. Through detailed examination of Touchon and Warkentin’s research, we investigated how predators influence the value of red color on the tails of tadpoles, Dendropsophus ebaraccatus. Hence, we aimed to determine if the average red value was influenced by predators through image analysis.
Based on this information, we hypothesized that if tail color is plastic within the tadpoles, the tadpoles with redder, thus darker, tails will be more prevalent in an environment with predators. Thus, their tails will have an increased average red value. The darker color would allow the tadpoles to decrease their visibility to predators and become less likely to be consumed compared to tadpoles with more transparent, less red tails. Since the red color is similar to foliage and sludge found at the bottom of the ponds, the tadpoles will be able to camouflage themselves and potentially avoid any ambush attacks. To test our hypothesis, we compared the average red color value of those tadpoles in the presence of a dragonfly predator and to a control group.