Ontogeny of escape-hatching decisions vibrational cue use changes as predicted from costs of sampling and false alarms

• Published in: Behavioral ecology and sociobiology Vol. 73; no. 4; pp. 1 - 14
• Main Authors: Warkentin, Karen M., Jung, Julie, Solano, L. Alberto Rueda, McDaniel, J. Gregory
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Science + Business Media 01.04.2019; Springer Berlin Heidelberg; Springer Nature B.V
• Subjects: Agalychnis callidryas; Alarms; Animal behavior; Animal Ecology; Animal populations; animals; behavior change; Behavioral Sciences; Biomedical and Life Sciences; Cues; Decision making; Developmental stages; eggs; Embryos; Frequency spectrum; Frogs; Hatching; learning; Life Sciences; mortality; Ontogeny; ORIGINAL ARTICLE; Playback; Playbacks; Predation; Predators; prediction; rain; risk; Risk acceptance; Risk assessment; Sampling; tadpoles; Tradeoffs; Vibration; Vibration control; Vibrations; Zoology; Biotremology; Ontogenetic adaptation; Risk assessment; Vibration playback; Environmentally cued hatching; Embryo behavior
• DOI: 10.1007/s00265-019-2663-2
• ISSN: 0340-5443

As animals develop, their abilities and needs change, altering cost/benefit trade-offs and optimal behavior responses to cues. We tested if ontogenetic changes in information use and environmentally cued hatching decisions of embryos match adaptive predictions, using red-eyed treefrogs, Agalychnis callidryas. These arboreal embryos hatch rapidly and prematurely to escape egg predators, cued by physical disturbance in attacks. Hatching early increases tadpole mortality, and premature embryos use multiple frequency and temporal properties of vibrations to assess risk, avoiding false alarms in benign disturbances such as rain. Because development increases hatchling survival, we hypothesized embryos approaching spontaneous hatching would reduce vibration sampling to reduce egg-predation risk, accepting more false alarms if cues are time-consuming to assess. We designed stimuli to elicit high or low hatching of younger embryos, with the property that reduces hatching either rapidly evident (frequency spectrum or fast temporal pattern) or time-consuming to assess (slow temporal pattern). We developed a new egg-tray vibration playback system to present motion-only cues with minimal disturbance in setup, then used it to compare responses of younger and previously untestable older embryos. The playback duration embryos experienced before or without hatching decreased with age, suggesting reduced vibration sampling. At both stages, hatching responses differed between frequencies, and among temporal patterns; nearly full-term embryos still showed selective hatching responses to cues. Hatching increased developmentally in a stimulus-dependent manner, with the greatest change in response to the slow pattern, as predicted. Developmental changes in discrimination appear well-matched to changing trade-offs, consistent with ontogenetic adaptation of embryo behavior.