Detecting Patterns of Natural Selection and Evolution in the Eye Transcriptome of Six Heliconius Species Using a 454 Next Generation Sequencing and Bioinformatic Approaches

A central goal of ecological and evolutionary research is to understand how adaptive variation arises, spreads, and influences the origin of new species. Amongst potential study systems, Heliconius butterflies offer exceptional opportunities for genomic level studies designed to understand how morphological diversity and new species are generated in nature. Heliconius butterflies stand as good models for evolutionary research because of the great amount of variation between the color patterns of their wings that allows us to study variation within species. Studies have shown that Heliconius butterflies mate assortatively, which suggest an association between wing color pattern and visual preference. With our study we want to explore the genomic basis of visual perception by analyzing the eye transcriptome in six Heliconius butterflies species, each of them representing a very distinct wing color pattern within the genus.  We extracted the mRNA from the entire eye for each of the six Heliconius species, barcoded and then pyrosequenced utilizing half plate of the Next Generation Sequencer (NGS) GS FLX Titanium Roche 454. Using the H. melpomene reference genome we obtain between 6000 and 12000 contigs depending on the particular species considered, with an average size of 750 bp and an inferred error rate of 1.3%. Our goal is to utilize this information to identify unusually rapidly and slowly evolving eye genes across our Heliconius species and to determine protein evolution. Finally we will generate a list of genes under positive selection and functional diversification that might underlie the evolution of specific color perception.