Distinct associative learning abilities for colour and odour in the flower-feeding Drosophila elegans and the fruit-feeding Drosophila melanogaster

Animal behavior is a blend of innate limitations and learning adaptations. This intricate balance has emerged due to species-specific ecological requirements and can vary across sensory perception types. Flower-visiting organisms provide an ideal model for studying the interplay between sensory ecology and learning, as they depend on various floral signals, notably odor and color, for food acquisition.

However, it has been largely unknown whether specialization on floral rewards leads to differences in learning capabilities across different sensory channels. Drosophila elegans, a flower-eating species, heavily relies on floral resources throughout its life cycle, with adult flies spending significant time on flowers and larvae developing on decaying floral remnants.

In this study, we compared associative learning between odor-reward and color-reward stimuli in Drosophila elegans and Drosophila melanogaster, which feeds on fruits and relies less on floral cues. Our findings indicate that under equal motivation conditions, while D. elegans performed worse in odor-reward learning, it outperformed D. melanogaster in color-reward learning when both stimuli were associated with the same sugar reward.

These results imply that the selective availability of sensory information for associative learning, known as the Garcia-effect in experimental psychology, can evolve differently across species. This demonstrates the connection between ecological specialization and memory processing, revealing that biological intelligence varies among organisms.