This project will study the origins of aposematism as a defensive strategy linking toxic chemicals and warning signals. This complex trait is thought to have started in cryptic ancestors and evolved through intermediate stages toward an optimal defense strategy. Aposematic poison frogs (Dendrobatidae) are well-studied, and these amphibians display an array of colors (reds, blues, and yellows) that advertise their skin alkaloids obtained from their diet. In contrast, their ancestors are less well-understood but similar to present-day dendrobatids that are non-aposematic, which include two-thirds of the known species in this family of amphibians. These frogs are assumed to be toxin-free, brown or black in color, and to follow a camouflage-based defense. We plan to study these organisms to explain how aposematism evolved in the first place. To investigate this, we will compare the skin profiles of aposematic and non-aposematic species and identify evolutionary signatures in dendrobatid lineages considered non-aposematic as intermediate stages toward aposematism. This integrated approach combines biochemistry, genetics, and evolutionary analyses. Our project also emphasizes the education of teachers with several outreach initiatives that engage participants at all levels and that are open to all Americans from high school to college students and beyond. Hands-on workshops will cover phylogenetics, genomics, chemical analysis, and bioinformatics, supported by online courses and op