 In biology specifically, "heterotopy" refers to an altered location of trait expression.In her book "Developmental Plasticity and Evolution", Mary-Jane West Eberhard has a cover art of the sulphur crested cockatoo and comments on the back cover "Did long crest[head] feathers evolve by gradual modification of ancestral head feathers?Or are they descendants of wing feathers, developmentally transplanted onto the head".