Ontogenetic Variation in the Chemical Defenses of Cane Toads (Bufo marinus): Toxin Profiles and Effects on Predators

Hayes, R. Andrew, Crossland, M. R., Hagman, M, Capon, R. J. and Shine, R (2009) Ontogenetic Variation in the Chemical Defenses of Cane Toads (Bufo marinus): Toxin Profiles and Effects on Predators. JOURNAL OF CHEMICAL ECOLOGY, 35 4: 391-399. doi:10.1007/s10886-009-9608-6


Author Hayes, R. Andrew
Crossland, M. R.
Hagman, M
Capon, R. J.
Shine, R
Title Ontogenetic Variation in the Chemical Defenses of Cane Toads (Bufo marinus): Toxin Profiles and Effects on Predators
Formatted title
Ontogenetic Variation in the Chemical Defenses of Cane Toads (Bufo marinus): Toxin Profiles and Effects on Predators
Journal name JOURNAL OF CHEMICAL ECOLOGY   Check publisher's open access policy
ISSN 0098-0331
1573-1561
Publication date 2009-04-01
Year available 2009
Sub-type Article (original research)
DOI 10.1007/s10886-009-9608-6
Open Access Status Not yet assessed
Volume 35
Issue 4
Start page 391
End page 399
Total pages 9
Editor John T Romero
Place of publication Netherlands
Publisher Spirnger Netherlands
Language eng
Subject C1
960406 Control of Pests, Diseases and Exotic Species in Fresh, Ground and Surface Water Environments
030502 Natural Products Chemistry
Abstract We conducted a quantitative and qualitative chemical analysis of cane toad bufadienolides—the cardioactive steroids that are believed to be the principal cane toad toxins. We found complex shifts in toxin composition through toad ontogeny: (1) eggs contain at least 28 dominant bufadienolides, 17 of which are not detected in any other ontogenetic stage; (2) tadpoles present a simpler chemical profile with two to eight dominant bufadienolides; and (3) toxin diversity decreases during tadpole life but increases again after metamorphosis (larger metamorph/juvenile toads display five major bufadienolides). Total bufadienolide concentrations are highest in eggs (2.64 ± 0.56 μmol/mg), decreasing during tadpole life stages (0.084 ± 0.060 μmol/mg) before rising again after metamorphosis (2.35 ± 0.45 μmol/mg). These variations in total bufadienolide levels correlate with toxicity to Australian frog species. For example, consumption of cane toad eggs killed tadpoles of two Australian frog species (Limnodynastes convexiusculus and Litoria rothii), whereas no tadpoles died after consuming late-stage cane toad tadpoles or small metamorphs. The high toxicity of toad eggs reflects components in the egg itself, not the surrounding jelly coat. Our results suggest a dramatic ontogenetic shift in the danger that toads pose to native predators, reflecting rapid changes in the types and amounts of toxins during toad development.
Formatted abstract
We conducted a quantitative and qualitative chemical analysis of cane toad bufadienolides—the cardioactive steroids that are believed to be the principal cane toad toxins. We found complex shifts in toxin composition through toad ontogeny: (1) eggs contain at least 28 dominant bufadienolides, 17 of which are not detected in any other ontogenetic stage; (2) tadpoles present a simpler chemical profile with two to eight dominant bufadienolides; and (3) toxin diversity decreases during tadpole life but increases again after metamorphosis (larger metamorph/juvenile toads display five major bufadienolides). Total bufadienolide concentrations are highest in eggs (2.64 ± 0.56 μmol/mg), decreasing during tadpole life stages (0.084 ± 0.060 μmol/mg) before rising again after metamorphosis (2.35 ± 0.45 μmol/mg). These variations in total bufadienolide levels correlate with toxicity to Australian frog species. For example, consumption of cane toad eggs killed tadpoles of two Australian frog species (Limnodynastes convexiusculus and Litoria rothii), whereas no tadpoles died after consuming late-stage cane toad tadpoles or small metamorphs. The high toxicity of toad eggs reflects components in the egg itself, not the surrounding jelly coat. Our results suggest a dramatic ontogenetic shift in the danger that toads pose to native predators, reflecting rapid changes in the types and amounts of toxins during toad development.
Keyword Anuran
Aquatic insect predators
bufadienolides
Bufo marinus
toxicity
ontogeny
cardiac steriods
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes First published online 5 March 2009

Document type: Journal Article
Sub-type: Article (original research)
Collections: 2010 Higher Education Research Data Collection
Institute for Molecular Bioscience - Publications
 
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Created: Thu, 03 Sep 2009, 18:11:42 EST by Mr Andrew Martlew on behalf of Institute for Molecular Bioscience