Mother chemical defenses predict offspring defenses in a dendrobatid poison frog

Abstract

Within and among populations, alkaloid defenses of the strawberry poison frog ( Oophaga pumilio ) vary spatially, temporally, and with life history stage. Natural variation in defense has been implicated as a critical factor in determining the level of protection afforded against predators and pathogens. Oophaga pumilio tadpoles sequester alkaloids from nutritive eggs and are thus entirely dependent on their mothers for their defense. However, it remains unclear how tadpole alkaloid composition relates to that of its mother and how variation in maternally provisioned defenses are effective against predators. Here, we demonstrate that natural variation in the alkaloid composition of mother frogs is reflected as variation in her tadpole’s alkaloid composition. Tadpoles, like mother frogs, varied widely in their alkaloid composition but always contained the identical alkaloids found in their mother. Alkaloid quantity in late stage tadpoles was highly correlated with alkaloid quantity in their mothers, and alkaloid quantity was the best predictor of tadpole palatability, wherein tadpoles with higher alkaloid quantities were less palatable. Mother frogs that provide greater quantities of alkaloids to their tadpoles likely ensure better protection for their offspring by providing defenses during one of the most vulnerable periods of life.