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Re-emergence and diversification of a specialized antennal lobe morphology in ithomiine butterflies.

Published version
Peer-reviewed

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Authors

Morris, Billy J 
Couto, Antoine 
Aydin, Asli 
Montgomery, Stephen H 

Abstract

How an organism's sensory system functions is central to how it navigates its environment. The insect olfactory system is a prominent model for investigating how ecological factors impact sensory reception and processing. Notably, work in Lepidoptera led to the discovery of vastly expanded structures, termed macroglomerular complexes (MGCs), within the primary olfactory processing centre. MGCs typically process pheromonal cues, are usually larger in males, and provide classic examples of how variation in the size of neural structures reflects the importance of sensory cues. Though prevalent across moths, MGCs were lost during the origin of butterflies, consistent with evidence that courtship initiation in butterflies is primarily reliant on visual cues, rather than long distance chemical signals. However, an MGC was recently described in a species of ithomiine butterfly, suggesting that this once lost neural adaptation has re-emerged in this tribe. Here, we show that MGC-like morphologies are widely distributed across ithomiines, but vary in both their structure and prevalence of sexual dimorphism. Based on this interspecific variation we suggest that the ithomiine MGC is involved in processing both plant and pheromonal cues, which have similarities in their chemical constitution, and co-evolved with an increased importance of plant derived chemical compounds.

Description

Keywords

Chemical ecology, ithomiini, neural adaptation, olfaction, pheromones, sexual signaling, Animals, Butterflies, Insecta, Male, Moths, Pheromones, Smell

Journal Title

Evolution

Conference Name

Journal ISSN

0014-3820
1558-5646

Volume Title

Publisher

Wiley