Transcriptional basis of cold adaptation in Drosophila melanogaster

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The fruit fly Drosophila melanogaster is originally an Afro-tropical species. Only recently (within the last 15,000 years) has it conquered new habitats like Europe. Obviously, this novel European environment differs greatly from the species origin, e.g. in mean temperature and the severity and length of winter. This project aims at uncovering genes which contributed to local adaptation during the range expansion into temperate habitats. Specifically, we are interested in changes in the genome that altered levels of gene expression. To find these we plan to expose European and African flies to a cold shock and measure their transcriptional response using whole-genome microarrays. Genes that show expression differences are candidates that may have undergone regulatory adaptation in order to provide increased cold tolerance. Furthermore, we would like to investigate if such adaptive changes are the results of cis- or trans-regulatory mutations. The use of flies with homogenized genomic backgrounds will allow us to address this question. Finally, we would like to functionally test if changes in transcription level of candidate genes are actually causative of differences in cold tolerance by using the transgenic tools available in D. melanogaster, which allow us to artificially increase or decrease expression levels of genes.