title: Acute changes in whole body corticosterone in response to perceived predation risk: A mechanism for anti-predator behavior in anurans?
abstract: Anuran larvae exhibit behavioral and morphological plasticity in response to perceived predation risk, although response type and magnitude varies through ontogeny. Increased baseline corticosterone is related to morphological response to predation risk, whereas the mechanism behind behavioral plasticity remains enigmatic. Since tadpoles alter behavioral responses to risk immediately upon exposure to predator cues, we characterized changes in whole body corticosterone at an acute (<1h post-exposure) timescale. Tadpoles (Lithobates sylvaticus) at Gosner stage (GS) 25 (free-swimming, feeding larvae) increased corticosterone levels to a peak at 10-20min post-exposure to predator cues, paralleling the acute stress response observed among other taxa. Tadpoles reared for 3weeks (mean GS29) with predation risk (caged, fed Aeshnid dragonfly nymph) had lower corticosterone levels at 10-20min post-exposure to dragonfly cues than predator-naïve controls, suggesting habituation, although the magnitude of increase was markedly diminished when compared to younger tadpoles (GS25). These experiments represent the first assessment of tadpole hormonal responses to predation risk at the acute timescale. Further research is required to establish causality between hormonal responses and behavioral changes, and to examine how and why responsiveness changes over ontogeny and with chronic exposure to risk.
authors.affiliation: Environmental and Life Sciences Graduate Program, Trent University, 1600 West Bank Drive, Peterborough, Ontario K9J 7B8, Canada. Electronic address: abennett@trentu.ca.
authors.forename: Amanda M
authors.initials: AM
authors.lastname: Bennett
authors.affiliation: Environmental and Life Sciences Graduate Program, Trent University, 1600 West Bank Drive, Peterborough, Ontario K9J 7B8, Canada.
authors.forename: Jessica N
authors.initials: JN
authors.lastname: Longhi
authors.affiliation: Environmental and Life Sciences Graduate Program, Trent University, 1600 West Bank Drive, Peterborough, Ontario K9J 7B8, Canada.
authors.forename: Eunice H
authors.initials: EH
authors.lastname: Chin
authors.affiliation: Environmental and Life Sciences Graduate Program, Trent University, 1600 West Bank Drive, Peterborough, Ontario K9J 7B8, Canada; Biology Department, Trent University, Life & Health Science Building, 2140 East Bank Drive, Peterborough, Ontario K9J 7B8, Canada.
authors.forename: Gary
authors.initials: G
authors.lastname: Burness
authors.affiliation: Environmental and Life Sciences Graduate Program, Trent University, 1600 West Bank Drive, Peterborough, Ontario K9J 7B8, Canada; Biology Department, Trent University, Life & Health Science Building, 2140 East Bank Drive, Peterborough, Ontario K9J 7B8, Canada.
authors.forename: Leslie R
authors.initials: LR
authors.lastname: Kerr
authors.affiliation: Environmental and Life Sciences Graduate Program, Trent University, 1600 West Bank Drive, Peterborough, Ontario K9J 7B8, Canada; Biology Department, Trent University, Life & Health Science Building, 2140 East Bank Drive, Peterborough, Ontario K9J 7B8, Canada.
authors.forename: Dennis L
authors.initials: DL
authors.lastname: Murray
mesh_terms: D000818:Animals; D001001:Anura / Q000502:physiology*; D003345:Corticosterone / Q000378:metabolism*; D011235:Predatory Behavior / Q000502:physiology*; D013312:Stress, Physiological
chemical_list: D003345:Corticosterone
keywords: Glucocorticoid; Hypothalamic–interrenal axis; Lithobates sylvaticus; Stress response; Wood frog