DNA Sequence Variation in the Wingless Gene Product in Buckeye Butterflies (Genus Junonia)
Wingless is a highly conserved gene important to cell determination in development. In Drosophila, the wingless gene product has been identified as responsible for wing patterning. In Bicyclus anynana and Junonia coenia, wingless gene product is expressed in a fashion that suggests that it is involved in butterfly wing color pattern development. The wingless gene product has been implicated as a potential focal signal for patterning the eyespot of Junonia butterflies. I have shown that extensive DNA sequence variation (26.04% of the sequenced region) exists in 402 bp of wingless coding sequence among 338 specimens of Junonia from Florida, Texas, Kentucky, California, and Argentina, representing 6 nominal species. Much of the identified variation is synonymous, but it alters codon usage and therefore has the potential to affect the amount of gene product produced. A common haplotype that uses unfavored codons has been identified and this might account for smaller eyespots. Positions of non-synonymous variation have been also been identified among the samples studied which may affect the behavior of the wingless gene product. The variation in wingless sequence was also used to examine geographical and nominal species population structure among different Junonia populations.