The Chemical Arsenal of Amazonian Tree Frogs: Evolutionary Diversification of Skin Peptides across Phyllomedusidae

Amphibian poisons are one of the most complex chemical defense systems among vertebrates, yet their diversity remains largely unresolved. Here, we present a comparative peptidomic analysis of six Amazonian species of Monkey Tree Frogs (Phyllomedusidae) sampled across three geographic regions. Mass spectrometry-based profiling revealed 18,466 features. Despite this extensive diversity, a subset of 961 features was shared across all species, while thousands of additional features were restricted to individual taxa or combinations of taxa. Poison profiles showed a highly uneven relative abundance distribution, with a small number of peptides accounting for a large proportion of the detected signal. Phylloseptins and dermaseptins were prominent components of several profiles, whereas bradykinin-related peptides, tryptophyllins, dermorphin-like peptides, medusins, and phyllomedusins showed variable contributions across taxa and regions. Geographic variation in the relative abundance of major peptide subfamilies indicates differences in peptide composition among the sampled populations. Such patterns are consistent with spatially structured variation and align with previous studies suggesting that amphibian peptide repertoires may be shaped by local ecological and biotic interactions. Our results reveal substantial variation in peptide composition and relative abundance while maintaining a broadly shared molecular component across phyllomedusid taxa. This study expands current knowledge of amphibian chemical diversity and provides new insights into how ecological and evolutionary processes may contribute to the diversification of chemical defense systems.