Genomic and transcriptomic analysis of diapausean important life history trait in Drosophila melanogaster. Xiaqing Zhao¹, Alan Bergland², Dmitri Petrov², Paul Schmidt¹. 1) Dept. of Biology, University of Pennsylvania, Philadelphia, PA; 2) Dept. of Biology, Stanford University, Stanford, CA.

   Diapause is a genetically determined syndrome cued by shortened photoperiod and/or reduced temperature that results in lifespan extension, delayed senescence, increased stress tolerance and reproductive quiescence. It is the primary adaptation in invertebrates to survive unfavorable seasons, and is a complex trait that links multiple processes including environmental sensing, biological rhythms and aging. In natural populations of Drosophila melanogaster, the expression of diapause is highly variable, making it possible to elucidate the genetic architecture and molecular basis of the trait. Here we exposed outbred natural populations to diapause-inducing conditions, and separated the population based on whether or not each individual fly expressed diapause. Pooled genomic DNA sequencing was performed on replicate diapause and non-diapause sets; pooled mRNA sequencing of heads and ovaries was also performed on the same populations. The transcriptome data show that many genes are up-regulated during diapause, indicating that diapause is an actively regulated process. This is especially true in heads, where the up-stream environmental sensing and neuroendocrine regulation of diapause presumably take place. The mRNAseq data are contrary to the traditional hypothesis that diapause is a passive response to adverse environments, and primarily involves a shut down or dampening of many biological processes. The genomic sequencing has identified a suite of sequence variants that are associated with the diapause phenotype. There is also a substantial overlap between genes whose sequence variation is associated with diapause incidence, and genes that are differentially expressed as a function of diapause initiation. GO enrichment analysis of the candidate genes has identified many interesting processes involved in diapause.