Life stage and interspecies variation in salamander quantity discrimination, and incipient learning

Area of Science:

• Comparative Cognition
• Amphibian Biology
• Evolutionary Psychology

Background:

• Quantity discrimination is crucial for decision-making and has ancient evolutionary roots.
• Understanding numerical abilities in amphibians, particularly during development, remains limited.

Purpose of the Study:

• To investigate relative quantity discrimination in larval and metamorph stages of Hynobius leechii and Salamandrella tridactyla.
• To explore how life-history stage and species influence spontaneous numerical cognition in salamanders.

Main Methods:

• A spontaneous food-choice task was employed with 32 larvae and 16 metamorphs from two salamander species.
• Individuals chose between two food quantities presented in a 1:8 ratio over 10 trials.
• Choice behavior, preference, and decision time were recorded across different life-history stages.

Main Results:

• No significant preference for larger or smaller food quantities was observed across most groups and life stages.
• Hynobius leechii metamorphs were the only group to show a statistically significant tendency to select larger quantities above chance.
• Decision time decreased over trials, suggesting habituation or task learning rather than quantity-specific learning; Salamandrella tridactyla made choices faster.

Conclusions:

• This study offers initial insights into quantity-related decision-making in salamanders across different life stages.
• Findings suggest that sophisticated quantity discrimination may not be widespread in amphibians, with some species-specific variation.
• The results contribute to understanding the evolution of numerical cognition and amphibian cognitive abilities.