First Evidence of Diverse Inhibitory Control Abilities in Pre- and Post-Metamorphic Salamanders.

Animals need inhibitory control to achieve goals when taking a detour, requiring self-regulation, decision-making, and spatial awareness to suppress direct approaches and find alternative routes. In amphibians, particularly salamanders, there is a considerable lack of information regarding inhibitory control. We examined this cognitive trait in two species of salamanders, Hynobius yiwuensis and Salamandrella tridactyla, across larval and post-metamorphic stages using a detour task where they had to navigate around a transparent barrier to reach food. Results indicate significant differences in detour behavior and inhibitory control across life-history stages and between species. While larvae of H. yiwuensis performed significantly better than the metamorphs in solving the task, metamorphs of S. tridactyla outperformed their larvae, with 100% of individuals successfully reaching the food. Task success, that is, reaching the food around the barrier, increased over trials, and individuals demonstrating greater persistence and lower latency were significantly more likely to succeed. Metamorphs exhibited significantly lower latency than larvae, indicating faster decision-making overall. However, this effect varied across species as H. yiwuensis metamorphs did not show reduced latency. Pecking and reverse (retreating from the barrier, reorienting, and approaching from a different direction), used as indicators of errors, decreased over successive trials, which could be interpreted as evidence of learning. Individuals of H. yiwuensis displayed significantly higher instances of committing errors compared to S. tridactyla. As individuals were lab-reared from eggs, the difference in cognitive abilities across species and developmental stages may reflect underlying genetic differences shaped by their distinct ecological adaptations and evolutionary trajectories.