TY - JOUR T1 - Brain composition in <em>Heliconius</em> butterflies, post-eclosion growth and experience dependent neuropil plasticity JF - bioRxiv DO - 10.1101/017913 SP - 017913 AU - Stephen H. Montgomery AU - Richard M. Merrill AU - Swidbert R. Ott Y1 - 2015/01/01 UR - http://biorxiv.org/content/early/2015/04/10/017913.abstract N2 - Behavioral and sensory adaptations are often based in the differential expansion of brain components. These volumetric differences represent differences in investment, processing capacity and/or connectivity, and can be used to investigate functional and evolutionary relationships between different brain regions. Here, we describe the brain composition of two species of Heliconius butterflies, a long-standing study system for investigating ecological adaptation and speciation. We confirm a previous report of striking mushroom body expansion, and explore patterns of post-eclosion growth and experience-dependent plasticity in neural development. This analysis uncovers two phases of post-emergence mushroom body growth comparable to those of foraging hymenoptera, but also identifies plasticity in several other neuropil. An interspecific analysis suggests Heliconius may display remarkable levels of investment in mushroom bodies for a Lepidopteran, and indeed rank highly compared to other insects. We also describe patterns of adaptive divergence in the volume of both peripheral and central neuropil within Heliconius, and across Lepidoptera, that suggest changes in brain composition plays an important role in ecological adaptation. Our analyses lay the foundation for future comparative and experimental analyses that will establish Heliconius as a useful case study in evolutionary neurobiology.Financial support This research was supported by research fellowships from the Royal Commission of the Exhibition of 1851 and Leverhulme Trust, a Royal Society Research Grant (RG110466) and a British Ecological Society Early Career Project Grant awarded to SHM. RMM was supported by a Junior Research Fellowship from King’s College, Cambridge and an Ernyst Mayr Fellowship from STRI. SRO was supported by a University Research Fellowship from the Royal Society, London (UK). ER -