Western chorus frog tadpoles (Pseudacris triseriata) show expedited development, but no change in tail morphology, in the presence of predators and independent of diet

Abstract

Environmental stressors, such as threat of predation can elicit a wide variety of physical and behavioral changes as organisms attempt to avoid predation. Tadpoles of many species are known to display some degree of anatomical, physiological, and/or behavioral plasticity in response to predators. Such epigenetic adjustments often carry costs, and thus, require proper nutrients to fuel the bodily changes. The focus of this study was to examine the impact of predator presence on a fast-developing tadpole species, Pseudacris triseriata, when fed diets of varying nutritional content. Tadpoles fed a high protein/high fat diet and exposed to a predator were hypothesized to undergo a quicker metamorphosis rate and develop a tail more effective for predator avoidance. The experimental group was exposed to a predator and fed either a diet high in protein and fat or a diet low in protein and fat. The control group had no predator and was fed either of the two diets. Growth, overall body length, tail depth at the base and midpoint, and progression through developmental stages were measured for all tadpoles. Faster development was found with the presence of a predator but no morphological tail defenses were made; this was independent of diet. As a species with the opportunistic ability to undergo expedited metamorphosis while living in temporary pools of water, our results suggests that it may be more beneficial for P. triseriata tadpoles to develop quicker and leave the pond to avoid a threat rather than invest in morphological changes that enhance escaping from predators in the water.