Brain size does not predict learning strategies in a serial reversal learning test.

Area of Science:

• Behavioral Ecology
• Neuroscience
• Evolutionary Biology

Background:

• Reversal learning assays assess associative learning and behavioral flexibility across species.
• Larger relative brain size is hypothesized to enhance learning ability and flexibility, explaining interspecific variation in performance.

Purpose of the Study:

• To experimentally test the hypothesis that larger relative brain size enhances behavioral flexibility at the intraspecific level.
• To investigate the relationship between brain size, neuron number, and performance in serial reversal learning using guppies.

Main Methods:

• Utilized guppies (Poecilia reticulata) artificially selected for small and large relative brain sizes.
• Assessed 96 individuals over 10 serial reversals in a binary discrimination task.
• Measured learning performance, memory, and efficient learning strategies.

Main Results:

• Learning performance and memory were significantly predicted by relative brain size.
• Differences in efficient learning strategies were not explained by brain size or neuron number.
• Intraspecific variation in brain size impacted learning and memory, but not strategy adoption.

Conclusions:

• Variation in brain size and neuron number is crucial for differences in learning performance and memory.
• These brain-related differences are insufficient to account for the significant variation in efficient learning strategies observed at higher taxonomic levels.