Date of Award

2020

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

First Advisor

Dr. Ralph Saporito

Abstract

Within and among populations, alkaloid defenses of strawberry poison frogs (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 to an individual from predators and pathogens. Oophaga pumilio tadpoles sequester defenses from nutritive eggs and are thus entirely dependent on their mothers for their alkaloids. However, it remains unclear how the alkaloid composition of a tadpole relates to that of its mother and if maternally provisioned defenses are effective against predators. Here, I demonstrate that natural variation in the alkaloid composition of mother frogs—even among individuals collected less than a few hundred meters apart—is reflected as variation in tadpole alkaloid composition. Mother frogs and their specific tadpoles were collected from La Selva Research Station in Costa Rica in order to make direct comparisons of the alkaloid profiles between mothers and their offspring. Additional tadpoles were collected for palatability assays to determine if maternally provisioned alkaloids provide meaningful protection from predators. Tadpoles, like mother frogs, varied widely in their alkaloid composition but contained the exact same types of alkaloids found in their mother. Late stage tadpole alkaloid quantity was highly correlated with the alkaloid quantity of the mother frog, and alkaloid quantity was the best predictor of tadpole palatability where tadpoles with higher alkaloid quantities were less palatable. Overall, the alkaloid profile of tadpoles are highly similar to that of their mother and variation in the alkaloid composition of mother frogs is translated as variation in the alkaloid composition of tadpoles. 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. Future studies 2 should examine how and if variation in alkaloid composition across the geographic range of O. pumilio translates to variation in tadpole alkaloid composition and the implications this has for protection from local predators and pathogens.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Available for download on Friday, August 06, 2021

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