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DOSAGE RESPONSE OF AN INDUCED DEFENSE: HOW SENSITIVE ARE TADPOLES TO PREDATION RISK?
Author(s) -
Van Buskirk Josh,
Arioli Martina
Publication year - 2002
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.1890/0012-9658(2002)083[1580:droaid]2.0.co;2
Subject(s) - predation , dragonfly , biology , ecology , larva , predator , trade off , escape response , zoology
Models of behavior and life history evolution under predation risk often assume that animals can detect and respond to subtle temporal and spatial variation in mortality risk, but there is little evidence supporting this assumption. We measured phenotypic responses of Rana lessonae tadpoles to variation in apparent predation risk signaled by different numbers of Aeshna dragonfly larvae consuming different quantities of tadpoles. The experiment took place in 80‐L artificial ponds, and the predators were confined within cages so that they could not capture the experimental animals. There was good support for continuous dosage response curves for most behavioral and morphological traits, which indicates sensitivity to graded risk and therefore supports the assumptions of many models. Behavioral traits were most responsive to the number of tadpoles killed by the predators, whereas morphological traits responded to the number of dragonflies independent of the predators' diet. The results imply that behavioral and morphological responses can be triggered by different cues, and suggest that increasing investment in defensive traits entails increasing fitness costs.