Influence of functional traits and trait syndromes on the vulnerability of amphibians and reptiles in the tropical dry forest of Oaxaca, Mexico

Abstract

Abstract Tropical dry forests are among the most threatened ecosystems worldwide, yet their biodiversity remains understudied compared to humid tropical forests. We integrated functional trait ecology with environmental vulnerability assessments to evaluate multi‑causal disturbances affecting amphibians and reptiles in Oaxaca, Mexico, a hotspot of endemism and biodiversity loss. Environmental Vulnerability Scores (EVS) were constructed for the complete herpetofaunal assemblage and compared against international (IUCN) and national (NOM‑059) classifications. Significant discrepancies emerged: reptiles (n = 222) exhibited higher EVS than amphibians (n = 99), yet 14% of reptile species and 2% of amphibian species remain Data Deficient or Not Evaluated by the IUCN. NOM‑059 assessments were more limited, with nearly half of species Not Listed. Trait‑based analyses revealed that landscape transformation drives species‑specific vulnerability. Amphibians were disproportionately affected due to endemicity, low abundance, and sensitivity to environmental change, compounded by pollution and disease. Reptiles, while more physiologically adaptable to climatic variability, were primarily impacted by direct persecution, exploitation, and habitat loss. Despite high functional redundancy across groups, our findings suggest that redundancy alone may not safeguard ecosystem functioning under intensified land‑use and climate change. This study underscores the value of functional traits and trait syndromes as indicators of vulnerability and as guides for conservation prioritization. By revealing mismatches between trait‑based vulnerability and existing conservation lists, our results highlight the need for updated, integrative frameworks that incorporate ecological, functional, and socio‑cultural dimensions to ensure the persistence of herpetofauna and the resilience of tropical dry forest ecosystems.