Date of Award


Degree Type


Degree Name

Master of Science (MS)



First Advisor

Dr. Ralph Saporito


The term ‘poison frog’ describes members of five anuran families that are capable of sequestering lipophilic, alkaloid-based chemical defenses from their prey. Alkaloid defenses can vary widely within and among poison frog species, mostly linked to differences in availability of arthropod prey at different scales. While research has mainly focused on alkaloid variation within the dendrobatid and mantellid poison frogs, bufonid poison frogs in the genus Melanophryniscus demonstrate high inter- and intra-species alkaloid variation, and some members are capable of both sequestering dietary alkaloids and synthesizing alkaloids metabolically. However, of the 31 species of Melanophryniscus, only eight have ever had their alkaloid profiles characterized. The goal of the present study was to characterize the alkaloid defenses of 11 species of Melanophryniscus, including eight species never previously examined. Additionally, I explored how alkaloid content varied between species and among populations and identified which species contained both sequestered and synthesized alkaloids. Fifty-nine individuals, representing the 11 species, were collected from sites throughout the Brazilian states of Santa Catarina and Rio Grande do Sul. Over 200 unique alkaloids were identified in Melanophryniscus, and alkaloid composition, quantity, and richness varied significantly between species and among populations, likely influenced by differences in arthropod communities throughout the study area. Additionally, two of the 11 species examined contained the synthesized alkaloid bufotenine. The findings of this study increase the number of Melanophryniscus examined for alkaloid content from eight to 16 species and verifies that alkaloid composition is highly varied within the genus. Future studies will likely reveal even greater diversity of alkaloids in this genus, as well as provide insight into how variation further impacts the ecology and biology of Melanophryniscus.

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