Data From: Eye darkening under dehydration stress in the Neotropical frog Boana punctata (Schneider, 1799)

Amphibians face significant dehydration challenges due to their permeable skin and weak water retention mechanisms, especially under ongoing global warming that predicts increasing land dryness. This makes the identification of physiological stress indicators crucial to assess hydric risk in amphibian populations. This study examines iris darkening as a response to dehydration in the neotropical tree frog (Boana punctata) under controlled conditions. Thirteen adult specimens were collected in the province of Chaco, Argentina, and subjected to sequential dehydration treatments (10, 20, and 30 minutes) under constant airflow (0.2 m/s), followed by two-hour rehydration. Changes in the eye iris were quantified using standardised photography. The results showed a progressive darkening of the iris, from 21.1% under full hydration to 70.7% after 30 minutes of dehydration, with a partial reversal to 48.6% of iris darkening after rehydration. A strong negative correlation was observed between the individual percentage of dehydration and the extent of darkening in the iris. Our findings underscore the significance of subtle phenotypic responses in evaluating species resilience to environmental change, particularly in regions experiencing increasing water stress due to climate variability. In addition, the method used may serve as a non-invasive quantitative physiological indicator of water stress in wild amphibian populations.