The molecular basis of Mullerian mimicry

see Edinburgh proposal

Mimicry among butterfly species is a commonly cited example of evolution and adaptation and Heliconius are perhaps the best studied example, but the molecular genetic basis of mimicry has never been studied. Here we will first clone a region containing several linked elements that control yellow patterns in H. melpomene. BAC clones spanning the region of interest will be identified and then fingerprinted to assemble contigs. Linkage mapping will be used to confirm the position of patterning genes relative to these physical markers. A tile path across the contig will then be chosen, sequenced and assembled. We will annotate these sequences to identify all the possible genes in this region that are candidates for being the patterning locus, and determine which ones are expressed in developing wings and whether they show any patterns that correlate with the wing patterns using transcriptomics and RNAi gene knock-down experiments. We expect to demonstrate spatial patterns of expression of the candidate locus that correlate with wing patterns, or alternatively temporal patterns of expression of the candidate locus during wing development that can be disrupted using RNAi experiments. Either way, we will identify a specific candidate for the Yb gene that controls a band on the hindwing of H. melpomene. We have recently shown that a homologous region controls pattern segregation in two further species, H. erato and H. numata. In H. numata the locus is a 'supergene' i.e. a single locus that controls all aspects of wing pattern and is polymorphic within populations We will then conduct a comparative analysis of this region in the three species, by repeating the chromosome walk in H. erato and H. numata and sequencing a similarly sized tile path in these two species. This will allow us to test whether genomic rearrangements have played a role in pattern evolution, as predicted by the theory of 'supergene' evolution.