Abstract
Up to 9 described species ofJunoniabutterflies occur in the Americas, but authorities disagree due to species similarities, geographical and seasonal variability, and possible hybridization. In dispute is whether CaribbeanJunoniaare conspecific with South American species.Cytochrome oxidase I(COI) barcodes,wingless(wg) sequences, and Randomly Amplified Fingerprints (RAF) were studied to revealJunoniapopulation structure in French Guiana, Guadeloupe, Martinique, and Argentina. Phylogenetic analysis ofCOIrecovered 2 haplotype groups, but mostJunoniaspecies can have either haplotype, soCOIbarcodes are ambiguous. Analysis of nuclearwinglessalleles revealed geographic patterns but did not identifyJunoniaspecies. Nuclear RAF genotyping distinguished 11 populations ofJunoniaarranged into 3 clusters. Gene flow occurs within clusters but is limited between clusters. One cluster included all Argentinian samples. Two clusters included samples from French Guiana, Martinique, and Guadeloupe and appear to be divided by larval host plant use (Lamiales versus Scrophulariales). ManyJunoniataxa were distributed across populations, possibly reflecting patterns of genetic exchange. We had difficulty distinguishing between the Caribbean formsJ. zonalisandJ. neildi, but we demonstrate that CaribbeanJunoniaare genetically distinct from South AmericanJ. evareteandJ. genoveva, supporting the taxonomic hypothesis that they are heterospecific.
Highlights
Buckeye butterflies, genus Junonia (Nymphalidae), are an important model system for experimental research in the Lepidoptera [1, 2]
Partial barcode sequences were obtained from miniCOIF/R sequences assembled into contigs with miniCOIF2/R2 sequences (2 specimens), miniCOIF/R sequences assembled into contigs with miniCOIF3/HCO2198 sequences (2 specimens), and miniCOIF2/HCO2198 sequences alone (16 specimens)
While the molecular tools employed here cannot yet distinguish between all named forms of Junonia we are getting much closer to having a set of reliable molecular markers for defining groups of populations within which genetic exchange is extensive and between which genetic exchange is limited, providing a means by which we can begin to distinguish between species
Summary
Genus Junonia (Nymphalidae), are an important model system for experimental research in the Lepidoptera [1, 2]. Junonia species have been widely used to study the evolution and development of butterfly wing colour patterns [2,3,4,5,6,7,8,9]. Experimental tools to manipulate gene expression developed in Junonia are broadly applicable across the Lepidoptera [10,11,12,13,14]. Junonia has been used in studies of insect endocrinology [15,16,17] and has been an important system for examining the evolution of larval host plant preference and tolerance to host plant toxins [18,19,20,21]. The species were described according to the standards of the time (without designated type specimens) and the descriptions were accompanied by hand-tinted plates that reproduced the colours from the original watercolour drawings of specimens of each form (republished in [26])
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