Physiological plasticity under dehydration as a driver of invasion success in the frog <i>Eleutherodactylus johnstonei</i>

Abstract Water balance strongly influences key physiological and ecological functions in terrestrial anurans, affecting locomotor performance and metabolism. Tolerance to dehydration may enable the capacity of invasive species to persist in novel environments. We investigated how progressive dehydration affects locomotor performance (endurance and power) and aerobic capacity in an invasive population of the whistling frog, Eleutherodactylus johnstonei, established in southeastern Brazil. We hypothesized that dehydration impairs both locomotor performance and aerobic capacity. Frogs were tested under three hydration levels: 100, 90, and 80% of body mass. Dehydration reduced endurance, decreasing the number of jumps at 90 and 80%, as well as total distance and maximum jump length only at 80%, while initial speed remained unaffected. In contrast, dehydration did not influence metabolic traits. These results suggest that E. johnstonei maintains short-term locomotor capacity and metabolic stability under moderate hydric stress, demonstrating functional plasticity that may facilitate activity, dispersal, and persistence in urban microhabitats. Such physiological resilience probably confers an adaptive advantage facilitating establishment and spread in disturbed or seasonally dry environments, emphasizing water balance as a central axis shaping invasion success in terrestrial amphibians, supporting the ecological success of E. johnstonei as an invasive species.