The occurrence of defensive alkaloids in non-integumentary tissues of the Brazilian red-belly toad Melanophryniscus simplex (Bufonidae)

Grant, Taran; Colombo, Patrick; Verrastro, Laura; Saporito, Ralph A.

doi:10.1007/s00049-012-0107-9

Cited by 35 publications

(26 citation statements)

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“…Very recent work (Grant et al 2012) on eleven M . simplex skins from three sites in Brazil indicates the occurrence of many new alkaloids or diastereomers of known dendrobatid alkaloids as we have observed with the Argentinian M .…”

Section: Resultsmentioning

confidence: 99%

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Alkaloids from single skins of the Argentinian toad Melanophryniscus rubriventris (ANURA, BUFONIDAE): An unexpected variability in alkaloid profiles and a profusion of new structures

et al. 2012

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GC-MS analysis of single-skins of ten Melanophryniscus rubriventris toads (five collections of two toads each) captured during their breeding season in NW Argentina has revealed a total of 127 alkaloids of which 56 had not been previously detected in any frog or toad. Included among these new alkaloids are 23 new diastereomers of previously reported alkaloids. What is particularly distinguishing about the alkaloid profiles of these ten collections is the occurrence of many of the alkaloids, whether known or new to us, in only one of the ten skins sampled, despite two skins being obtained from each breeding site of the five populations. Many of the alkaloids are of classes known to have structures with branched-chains (e.g. pumiliotoxins and tricyclic structures) that are considered to derive from dietary mites. A large number of previously reported and new alkaloids are also of unclassified structures. Only a very few 3,5-disubstituted-indolizidine or -pyrrolizidine alkaloids are observed that have a straight-chain carbon skeleton and are likely derived from ant prey. The possible relationship of these collections made during the toad’s brief breeding episodes to sequestration of dietary arthropods and individual alkaloid profiles is discussed.Electronic supplementary materialThe online version of this article (doi:10.1186/2193-1801-1-51) contains supplementary material, which is available to authorized users.

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Section: Resultsmentioning

confidence: 99%

“…The Brazilian species, M . simplex has recently been investigated and contains both known and new alkaloids (Grant et al 2012). A tenth species, M .…”

Section: Introductionmentioning

confidence: 99%

Alkaloids from single skins of the Argentinian toad Melanophryniscus rubriventris (ANURA, BUFONIDAE): An unexpected variability in alkaloid profiles and a profusion of new structures

et al. 2012

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“…Female cane toads (Rhinella marina) provision their eggs with bufadienolides, which renders the eggs and the hatched tadpoles toxic, but the quantity of the chemicals and their antipredator effectiveness decline across tadpole development (Hayes et al 2009). Eggs, but not tadpoles, of boreal toads (Anaxyrus [¼Bufo] boreas) are protected with bufadienolides (Benard and Fordyce 2003), and oocytes from redbelly toads (Melanophryniscus simplex) contain a variety of alkaloids (Grant et al 2012). Many parental amphibians chemically arm their eggs, but the effectiveness of these predator defenses generally decreases with offspring development (Hayes et al 2009, Santos andCannatella 2011).…”

Section: Introductionmentioning

confidence: 99%

Evidence of maternal provisioning of alkaloid‐based chemical defenses in the strawberry poison frog Oophaga pumilio

Stynoski

Torres-Mendoza

Sasa

et al. 2014

Ecology

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Abstract. Many organisms use chemical defenses to reduce predation risk. Aposematic dendrobatid frogs sequester alkaloid-based chemical defenses from a diet of arthropods, but research on these defenses has been limited to adults. Herein, we investigate chemical defense across development in a dendrobatid frog, Oophaga pumilio. This species displays complex parental care: at hatching, mothers transport tadpoles to phytotelmata, and then return to supply them with an obligate diet of nutritive eggs for about six weeks. We collected eggs, tadpoles, juveniles, and adults of O. pumilio, and detected alkaloids in all life stages. The quantity and number of alkaloids increased with frog and tadpole size. We did not detect alkaloids in the earliest stage of tadpoles, but alkaloids were detected as trace quantities in nutritive eggs and as small quantities in ovarian eggs. Tadpoles hand-reared with eggs of an alkaloid-free heterospecific frog did not contain alkaloids. Alkaloids that are sequestered from terrestrial arthropods were detected in both adults and phytotelm-dwelling tadpoles that feed solely on nutritive eggs, suggesting that this frog may be the first animal known to actively provision post-hatch offspring with chemical defenses. Finally, we provide experimental evidence that maternally derived alkaloids deter predation of tadpoles by a predatory arthropod.

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“…The Melanophryniscus genus is one of the lineages of poison anurans that sequester alkaloid defenses from dietary arthropods (Saporito et al , , ; Hantak et al , ). Alkaloid composition varies temporally and spatially, and among individuals and populations (Kwet et al , ; Daly et al , , ; Grant et al , ). Although all these differences in alkaloid composition are not well understood, they probably occur due to variation in habitat use and arthropod availability (Grant et al , ).…”

Section: Discussionmentioning

confidence: 99%

“…Alkaloid composition varies temporally and spatially, and among individuals and populations (Kwet et al , ; Daly et al , , ; Grant et al , ). Although all these differences in alkaloid composition are not well understood, they probably occur due to variation in habitat use and arthropod availability (Grant et al , ). A significant variation in the composition and quantity of alkaloids may reduce the avoidance response of predators and is compatible with our findings.…”

Section: Discussionmentioning

confidence: 99%

An experimental assessment of the antipredatory function of green dorsal coloration in poisonous Neotropical red‐bellied toads

et al. 2019

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Crypsis and aposematism are important forms of antipredatory strategies. Through cryptic coloration, animals reduce their detectability by matching the coloration of backgrounds, while through aposematic coloration, prey species signal to potential predators their unprofitability by conspicuous coloration. The efficacy of aposematism depends on a predator’s ability to identify and avoid unprofitable prey. Among amphibians, both strategies are well known for many species. Most species of red‐bellied toads, Melanophryniscus spp., present conspicuous coloration with a likely aposematic function, both dorsally and ventrally, and display the behavior known as the unken reflex. However, there are a few species, like M. cambaraensis, that only present ventral conspicuous coloration. The dorsal coloration of this species is dull green, which is usually associated with camouflage. Although this species is diurnal and toxic, the exposition of red ventral coloration does not seem to serve as an aposematic signal. Here, we evaluated experimentally if the green dorsal color of M. cambaraensis functions as warning coloration for visually oriented natural predators. We conducted field predation experiments using clay models, representing M. cambaraensis (green models) and a generalized cryptic frog (brown models), to compare attack rates between treatments. The avian attacks were concentrated mainly on the anterior end, suggesting models were perceived as prey. However, attack rates were similar on green and brown frog models. Our results suggest that the green dorsal color of the species does not act as an aposematic signal, but functions as a cryptic color. Although crypsis in poisonous species remains a complex topic, under certain circumstances, the selection pressures imposed by predators may favor a cryptic coloration instead of a conspicuous coloration, even for diurnal species.

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The occurrence of defensive alkaloids in non-integumentary tissues of the Brazilian red-belly toad Melanophryniscus simplex (Bufonidae)

Cited by 35 publications

References 33 publications

Alkaloids from single skins of the Argentinian toad Melanophryniscus rubriventris (ANURA, BUFONIDAE): An unexpected variability in alkaloid profiles and a profusion of new structures

Alkaloids from single skins of the Argentinian toad Melanophryniscus rubriventris (ANURA, BUFONIDAE): An unexpected variability in alkaloid profiles and a profusion of new structures

Evidence of maternal provisioning of alkaloid‐based chemical defenses in the strawberry poison frog Oophaga pumilio

An experimental assessment of the antipredatory function of green dorsal coloration in poisonous Neotropical red‐bellied toads

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