TWO THOUSAND GENERATIONS OF HYBRIDISATION IN A HELICONIUS BUTTERFLY.

Abstract

The neotropical butterfly Heliconius melpomnene (L.) is extremely polymorphic in some parts of its range. About fifty varieties have been named from three localities in the west of Guyane (French Guiana), where perhaps many thousands of specimens have been collected for export by dealers (Joicey and Kaye, 1917; 1919). As the butterfly is mimetic, mutually copying in strict parallel its relative H. erato (L.) and several other species in the genus (Turner, 1970; 1971a), and distasteful to birds (Brower, Brower and Collins, 1963), this polymorphism is extremely interesting as the mimicry is Muellerian rather than Batesian. Its genetics should cast light on the genetic architecture of Muellerian mimicry and, as Muellerian mimics tend to be monomorphic (Ford, 1953) the polymorphism is a little surprising. This paper sets out to show, by genetical and other evidence, that the polymorphism of H. melpomene in the Guianas is produced by the hybridisation of monomorphic subspecies, the importance of this conclusion being that it shows that the polymorphism is not anomalous, and that a correct understanding of the polymorphism is essential to any discussion of the genetic architecture of mimicry. When the hypothesis of hybridisation was first put forward, it produced certain