Shifting balances in the weighting of sensory modalities are predicted by divergence in brain morphology in incipient species of Heliconius butterflies.

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From: Animal Behaviour(Vol. 185)
Publisher: Elsevier B.V.
Document Type: Report; Brief article
Length: 316 words

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Abstract :

Keywords conflicting stimulus; Heliconius; learning; olfactory cue; visual cue Highlights * Divergence in brain sensory processing regions may reflect ecological need. * We tested whether this divergence affects foraging in two Heliconius butterflies. * Visual/olfactory cue association with positive rewards differed between species. * This sensory domain divergence is consistent with brain morphology divergence. Abstract Integrating and weighting sensory perception across modalities is crucial to how animals adapt to their environment. Divergence in brain structure is often in sensory processing regions, suggesting that investment reflects ecological needs. Here, we use two parapatric closely related species, Heliconius erato cyrbia and Heliconius himera, to test the hypothesis that divergence in sensory brain regions affects foraging decisions. These butterflies are isolated across an ecological gradient, which is linked to differences in brain morphology, with H. e. cyrbia investing more in visual centres and H. himera investing in olfactory centres. Here, we demonstrate that these two species vary in how they associate visual and olfactory cues with positive food rewards. We found that when individuals were trained on paired olfactory and visual stimuli, then presented with these stimuli in conflict, they showed distinct behavioural responses. Heliconius himera was more likely to favour positive olfactory cues than H. e. cyrbia, which favoured visual cues regardless of the paired stimulus. This suggests that these species have diverged in the emphasis placed on these different sensory domains during foraging, consistent with observed differences in brain morphology. This result strengthens evidence that speciation initiated by local adaptation is partly facilitated by changes in the neural basis of key behavioural functions. Author Affiliation: (a) Smithsonian Tropical Research Institute, Panama City, Panama (b) School of Biological Science, University of Bristol, U.K. * Corresponding author. Article History: Received 3 July 2021; Revised 13 September 2021; Accepted 2 November 2021 (miscellaneous) MS. number: A21-00416R Byline: Denise D. Dell'Aglio [denise.ddd3@gmail.com] (a,*), W. Owen McMillan (a), Stephen H. Montgomery (b)

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Gale Document Number: GALE|A695208887