Knowledge about the dynamics of regional diversity patterns is a foundation on which measures aimed to protect diversity dimensions in the light of climate change can be constructed. Here, we describe taxonomic, phylogenetic, and functional diversity patterns of amphibians in the Yucatan Peninsula and their representation in the current protected area system. We stacked current and future potential distribution models to estimate taxonomic diversity and, based on the most recent amphibian phylogeny and nine functional traits, we measured phylogenetic and functional diversity. Independent phylogenetic and functional metrics were obtained by applying null models that allowed us to identify the presumably signature mechanisms underlying assemblage formation. We evaluated the effectiveness of the protected areas in protecting diversity dimensions across scenarios. We found phylogenetic and functional clustering as a result of environmental filters that have allowed only recently diverged species with converged functional traits to establish. Nevertheless, random assemblages are more widespread possibly due to the opposite directions in which competition and environmental filtering are acting. Overall, a decrease in all diversity dimensions is projected under future climate change scenarios compared with the current time. None of the protected areas evaluated were effective in protecting diversity dimensions, stressing the need to complete the existing protected areas network.