Inference of adaptive gene expression by experim. evolution

Stressful temperature conditions cause substantial differences in gene expression between D. melanogaster strains. It is, however, not clear if these expression differences have fitness consequences. The proposed project aims to address this question by exposing recombinant genotypes of two D. melanogaster strains to heat stress at 29C for 20 generations. By monitoring the changes in gene expression it will be possible to identify selectively favored gene expression patterns. Pool-Seq analysis of the evolved populations will be used to identify the transcription factors driving this adaptive gene expression pattern.

This project studied the selection response of two different Drosophila melanogaster genotypes which were exposed to a novel hot environment. Very strong selection responses were seen already after 20 generations. Parallel populations starting from equal frequencies of the two founder genotypes resulted in highly parallel selection responses across the entire genome. When the same founder genotypes were cultivated at 18C very similar selection responses were seen-the major difference was that the selection response at 29C was stronger than at 18C. This implies that adaptation to laboratory conditions is the major driver of the selection responses and temperature modulates the selection response-a pattern which is consistent with an interaction between temperature and laboratory adaptation. The high parallelism observed between replicate populations suggests that this experimental setup can be used to dissect complex traits when the experiment is run for more generations. Some preliminary data were generated, which support this interpretation.