Cryptic speciation associated with geographic and ecological divergence in two Amazonian Heliconius butterflies

The evolution of reproductive isolation via a switch in mimetic wing coloration has become the paradigm for speciation in aposematic Heliconius butterflies. Here, we provide a counterexample to this, by documenting two cryptic species within the taxon formerly considered Heliconius derneter Staudinger, 1897. Amplified fragment length polymorphisms identify two sympatric genotypic clusters in northern Peru, corresponding to subspecies Heliconius demeter ucayalensis H. Holzinger & R. Holzinger, 1975 and Heliconius demeterjoroni ssp. nov. These subspecies are reciprocally monophyletic for the mitochondrial genes COI and COII and the nuclear gene Ef1 alpha, and exhibit marked differences in larval morphology and host plant use. COI sequences from 13 of the 15 currently recognized subspecies show that mtDNA differences are reflected across the range of H. demeter, with a deep phylogenetic split between the southern and northern Amazonian races. As such, our data suggest vicariant speciation driven by disruptive selection for larval performance on different host plants. We raise Heliconius demeter eratosignis (Joicey & Talbot, 1925) to Heliconius eratosignis based on nomenclatural priority, a species also comprising H. eratosignis ucayalensis comb. nov. and three other southern Amazonian races. Heliconius demeterjoroni spp. nov. remains within H. demeter s.s., along with northern Amazonian and Guianan subspecies1861233249CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP303834/2015-32011/50225-3; 2012/50260-6We thank NERC (NE/K012886/1) and BBSRC (BB/G006903/1) for funding this work. We also thank SERFOR and the Peruvian Ministry of Agriculture for collecting permits (288-2009-AG-DGFFS-DGEFFS, 0148-2011-AG-DGFFS-DGEFFS, 0289-2014-MINAGRI-DGFFS/DGEFFS), as well as the ACR Cordillera Escalera (020-014/GRSM/PEHCBM/DMA/ACR-CE, 040-2015/GRSM/PEHCBM/DMA/ACR-CE). We are grateful for discussions with Walter Neukirchen on this work. NR is very grateful to Ronald Mori Pezo for support in the field and his observations on the natural history of these species. Tamara M. C. Aguiar helped by spreading old specimens from Unicamp and Augusto H. B. Rosa helped photograph each specimen. Juan Grados photographed the holotype of Heliconius demeter joroni ssp. nov. We also thank Keith S. Brown Jr. and Eurides Furtado for kindly sharing pictures, specimens and unpublished information. Brazilian specimens are registered in the SISGEN (AACC442). AVLF acknowledges support from FAPESP (Biota-Fapesp – grants 2011/50225-3 and 2012/50260–6), from the Brazilian Research Council – CNPq (fellowship 303834/2015-3), from the National Science Foundation (DEB-1256742) and from USAID (Mapping and Conserving Butterfly Biodiversity in the Brazilian Amazon - PEER Cycle 4–478