Ontogenetic shifts in a prey's chemical defences influence feeding responses of a snake predator

Llewelyn, John, Bell, Kris, Schwarzkopf, Lin, Alford, Ross A., and Shine, Richard (2012) Ontogenetic shifts in a prey's chemical defences influence feeding responses of a snake predator. Oecologia, 169 (4). pp. 965-973.

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Foraging theory suggests that predator responses to potential prey should be influenced by prey chemical defences, but the effects of ontogenetic variation in such defences on prey vulnerability to predators remain unclear. Cane toads (Rhinella marina) are toxic to anurophagous snakes, including the keelback (Tropidonophis mairii, a natricine colubrid that occurs within the toads’ invasive range in Australia). Toxin levels and diversity change through toad ontogeny, decreasing from the egg stage to metamorphosis, then increasing in postmetamorphic toads. If the toxin content of a prey item influences predator responses, we predict that keelbacks should exhibit selective predation on toads close to metamorphosis. The results of our laboratory trials on adult (field-collected, and thus toad-experienced) and hatchling (laboratory-incubated, and thus toad-naive) keelbacks supported this prediction. The snakes selectively consumed later-stage rather than earlier-stage tadpoles, and earlier-stage rather than later-stage metamorphs. Our data are thus consistent with the hypothesis that ontogenetic changes in toxin content can affect individuals’ vulnerability to predation.

Item ID: 25385
Item Type: Article (Research - C1)
ISSN: 1432-1939
Keywords: chemical defence, ontogeny, optimal foraging, Bufo marinus
Funders: Australian Research Council (ARC)
Date Deposited: 12 Mar 2013 04:41
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060201 Behavioural Ecology @ 50%
06 BIOLOGICAL SCIENCES > 0603 Evolutionary Biology > 060303 Biological Adaptation @ 50%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960802 Coastal and Estuarine Flora, Fauna and Biodiversity @ 100%
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