Fear of Aquatic Predators Cause Prey to Alter Their Phenotype at Multiple Life Stages

ECU Author/Contributor (non-ECU co-authors, if there are any, appear on document)

Scott P Jones (Creator)

Institution

East Carolina University (ECU )

Web Site: http://www.ecu.edu/lib/

Abstract: Many organisms can alter their behavior, life history, and morphology in response to their environment. This ability is known as phenotypic plasticity. One of the major environmental cues that triggers a phenotypic plastic response in some organisms is the threat of predation. Predator-induced phenotypic plasticity is finely tuned and organisms can respond differently to different types of predators and responses to a predator can carry over across life stages. These carry over effects may represent trade-offs associated with responding to predators because an adaptive response in one life stage may not be adaptive in a later life stage. In addition, many organisms show phenotypic plasticity in response to competitors and competitor-induced responses are often opposite of predator-induced responses. Since responses to predators are finely tuned and competitors also affect phenotypic plasticity, it remains to be seen as to what extent competitor identity (intra- and interspecific), age, and relative abundance alter the plastic phenotypic response to predators. We sought to determine the extent to which anti-predator responses in an early life stage persist into a later life stage in a natural setting, how competitor age and identity affect the response to a predator, and how the relative strength of intra- and interspecific competition affect the response of two co-occurring prey species to a predator. We used artificial ponds and larval frogs and toads to address these effects. Southern toads altered their life history and morphology in response to predators but the particular response depended on predator identity. Morphological differences that developed in response to aquatic predators during their larval stage carried over into their terrestrial juvenile stage, but differences only persisted for approximately one month after metamorphosis. Competitors alone had little effect on morphology, but they did strongly affect survival and life history. Predators on the other hand had strong effects on morphology, but competitors altered the way that pinewoods treefrogs responded to the predators. In particular, older intraspecific competitors caused pinewoods treefrogs to develop the most extreme defenses to predators. We also found that the relative strength of intra- and interspecific competition depends on the identity of the species involved. Pinewoods treefrogs seem to be poorer competitors than Cope's gray treefrogs and southern leopard frogs, and both pinewoods treefrogs and leopard frogs survived and grew better when there were more pinewoods present than leopard frogs. Predator identity, competitor age, competitor identity, and the relative strength of intra- and interspecific competition all affected the plastic phenotypic response of frogs and toads to a predator. Responses to a predator in one life stage also carry over into later life stages. These results highlight the importance of adding back the complexity of natural systems into experiments to gain a better understanding of how organisms can persist with predators.

Additional Information

Publication

Dissertation

Language: English

Date: 2016

Keywords

Predator

Subjects

Competition (Biology); Toads--Behavior; Phenotypic plasticity; Predation (Biology); Frogs--Behavior

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