Convergent Evolution in the Genetic Basis of Mullerian Mimicry in Heliconius Butterflies

The neotroptical butterflies Heliconius melpomene and H. erato are Mullerian mimics that display the same warningly colored wing patterns in local populations, yet pattern diversity between geographic regions. Linkage mapping has previously Shown convergent red wing phenotypes in these species are controlled by loci on homologous chromosomes. Here, AFLP bulk segregant analysis using H. melpomene crosses identified genetic markers tightly linked to two red wing-patterning loci. These markers were used to screen a H. melpomene BAC library and a the path was assembled spanning one locus completely and part of the second. Concurrently, a similar strategy was used to identify a BAC clone Lightly linked to the locus controlling the mimetic red wing phenotypes in H. erato. A methionine rich storage protein (MRSP) gene was identified within this BAC clone, and comparative genetic mapping shows red wing color loci are in homologous regions of the genome of H. erato and H. melpomene. subtle differences in these convergent phenotypes imply they evolved independently using somewhat. different developmental routes, but are nonetheless regulated by the same switch locus. Genetic mapping of MRSP in a third related species, the tiger patterned H. numata, has no association with wing patterning and shows no evidence for genomic translocation of wing-patterning loci.