Strawberry poison frogs (Oophaga pumilio) of Costa Rica give their newborn tadpoles a built-in weapon against predators: alkaloids
According with Ralph Saporito of John Carroll University in Ohio and leader of a new study on the species, adult strawberry poison frogs get the chemicals from their diets of ants and mites, “which essentially makes the frogs unpalatable to many potential predators”.
The team already knew that strawberry poison frog mothers feed their babies unfertilized eggs. But their new research revealed the eggs are also spiked with alkaloids—the first time an animal has been found to pass on such chemical defenses to its offspring.
For their study, the researchers measured alkaloid content in strawberry poison frogs during different stages of development. In one group, tadpoles were reared and fed by their mothers, and a second group was reared by the researchers and fed with eggs from another species of frog not known to harbor alkaloids.
As the tadpoles from both groups developed, the team analyzed their alkaloid contents. The results were clear-cut: Tadpoles reared by mom contained alkaloids in most stages, whereas tadpoles from the second group showed no sign of these chemicals, according to the study, published November 12 in the journal Ecology.
With this research scientist provide experimental evidence that maternally derived alkaloids deter predation of tadpoles by a predatory arthropod.
Sources: National Geographic and Stynoski et al., 2013
Photography: Strawberry poison arrow frog (Oophaga pumilio) in by Paul Bertner