title: Hybrid zones and the speciation  continuum in Heliconius butterflies.
abstract: Tropical butterflies in the genus Heliconius have long been models in the study of the stages of speciation. Heliconius are unpalatable to predators, and many species are notable for multiple geographic populations with striking warning colour pattern differences associated with Müllerian mimicry. A speciation continuum is evident in Heliconius hybrid zones. Examples range from hybrid zones across which (a) there is little genetic differentiation other than at mimicry loci, but where hybrids are common, (b) to 'bimodal' hybrid zones with strong genetic divergence and few hybrids, (c) through to 'good' sympatric species, with hybridization extremely rare or absent. Now, in this issue of Molecular Ecology, Arias et al. (2012) have found an intermediate case in Colombian Heliconius cydno showing evidence for assortative mating and molecular differences, but where hybrids are abundant.
authors: Galton Laboratory, Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK. jmallet@oeb.harvard.edu
authors: James
authors: J
authors: Mallet
authors: Kanchon K
authors: KK
authors: Dasmahapatra
mesh_terms: D000818:Animals; D002080:Butterflies / Q000235:genetics*; D002678:Chimera; D005260:Female; D005828:Genetics, Population; D008297:Male