Artificially adaptive neuroanatomical specialisations in domestic pigeon (columba livia) breeds

Abstract

The domestication of wild Rock Pigeons (Columba livia) has formed many breeds unique in behaviour, such as homing in homing pigeons and sexual displaying in cropper pigeons. Specialised behaviours are likely facilitated by concomitant changes in regional brain anatomy. Here we test how selection for behaviour is associated with neuroanatomical variation by comparing hippocampal formation (HF) and septal volume and neuron number across domestic and feral pigeons. We found significant neuroanatomical variation among breeds. Cropper pigeons have larger septum volumes, whereas homing pigeons have larger HF volumes and relatively smaller septum volumes. Furthermore, homing pigeons have significantly more HF neurons than most breeds, and twice as many HF neurons as feral pigeons, a finding we attribute to selection for homing. Cropper pigeons have more HF and septal neurons than most other breeds. These results suggest artificial selection for behaviour might be accompanied by significant changes in neuron number and density.