Population genomics and environmental adaptation in Drosophila ananassae

• Applicant: Dr. Sonja Grath
• Subject Area: Evolution, Anthropology
• Term: since 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 271330745

Temperature is one of the major factors influencing the geographical distribution and abundance of many animals. As ectothermic organisms, the body temperature of insects mainly follows the external environment and resilience towards thermal extremes is essential for adaptation to new environments such those arising through species expansion or climate change. In our laboratory, we established the fruit fly Drosophila ananassae as model organism to elucidate the genetic basis of adaptation to cold.In the first phase of this project, we revealed differences in gene expression between cold-tolerant and cold-resistant fly strains after exposure to a cold shock. Additional candidate genes for cold tolerance were identified using a genome-wide QTL mapping experiment. Furthermore, we set the ground work for genome editing by CRISPR/Cas in Drosophila ananassae. However, the function of these genes and their effect on the phenotype, in particular in tissues relevant for cold tolerance, remain unknown. Further, the focus of phase one was limited to one phenotype – chill coma recovery time (CCRT) – without taking into account periods of cold acclimation, which have been shown to influence cold tolerance in insects. In the second phase of the project, we plan to perform genome editing in several fly strains to knock-out gene expression or vary gene expression levels of these candidate genes. We will especially focus on tissue-specific genome editing in renal and gut tissues which were shown to be key physiological tissues for cold tolerance in Drosophila. We will further extend the selection of phenotypes and include cold acclimation. In addition, we aim to identify genome-wide polymorphisms related to cold tolerance based on genome sequencing of strains originating from two different populations. The results of these experiments will shed light on thermal adaptation of natural populations. In addition, the use of state-of-the-art genomic and genome editing methods will provide new information on the function of different genes, both in the whole organism and individual tissues. These data will not only elucidate the function of genes and polymorphisms associated with cold tolerance, but will also allow the analysis additional phenotypes and comparison with other species to identify general patterns of environmental adaptation.

• DFG Programme: Research Grants