ECOLOGICAL AND EVOLUTIONARY DRIVERS OF APOSEMATIC COLORATION IN POISON FROGS

Abstract

Aposematic coloration in poison frogs serves as a critical evolutionary strategy to deter predators by signaling chemical unpalatability. However, the ecological and evolutionary factors governing the diversity and maintenance of these visual signals across natural populations remain incompletely understood. This study investigates the multifactorial drivers of aposematic coloration in 10 populations of Neotropical poison frogs using a mixed-methods approach combining environmental analysis, predator-prey interactions, chemical profiling, mate choice assays, and genomic characterization. Field measurements revealed that environmental variables such as elevation, canopy cover, and humidity significantly influence color expression, with populations in higher, denser forests displaying cooler temperatures and greater predator richness. Spectral data showed that populations with higher skin brightness and saturation also exhibited elevated alkaloid concentrations, indicating a functional link between toxicity and signal conspicuousness. Predation trials using clay frog models demonstrated that attack rates were highest for red and orange morphs in open habitats, with birds being the predominant predators. Behavioral assays revealed strong female preferences for certain morphs (particularly red and blue), and higher preference scores were inversely correlated with approach latency, suggesting reinforcement through sexual selection. Multivariate analyses further indicated that environmental variables are strongly intercorrelated, influencing both predator distribution and prey availability, which in turn affect color and toxin expression. These results highlight the context-dependent nature of aposematism, showing that ecological gradients and predator diversity, along with sexual selection, jointly shape the evolution and maintenance of color polymorphisms in poison frogs. This study advances our understanding of signal evolution by elucidating how multiple selective forces act across spatial and behavioral dimensions in natural ecosystems.