Meeting Abstract

123.5  Monday, Jan. 7  The genetics of cold tolerance in fruit flies dissected using bulk segregant analysis of artificial selection lines NOH, S*; HAHN, DA; MORGAN, TJ; Kansas State University suegene.noh@gmail.com

A species’ ability to adapt to cold temperatures can determine species distributions and influence seasonality. Drosophila melanogaster falls into a reversible coma when exposed to zero to subzero temperatures. The recovery time is variable among individuals within the species, as well as populations along latitudinal clines, and also among other Drosophila spp. Chill coma recovery (CCR) is affected by developmental temperatures as well as previous exposures to cold. More significantly, it is possible to select flies for increased or decreased CCR, reflecting the significant genetic component underlying this trait. We used a bulk segregant analysis to dissect the genetics of this ecologically important complex trait. Previously, two replicate artificial selection lines were created from a single wild-caught population for high and low CCR. Two F2 populations were generated from each replicate and pooled Illumina sequencing libraries were prepared from the top and bottom 2.5% of each replicate phenotypic distribution. 50 bp paired-end reads from these libraries were sequenced on 4 lanes of an Illumina HiSeq 2000 instrument. Reads were aligned using a custom 2 step (stringent, then lenient) alignment procedure. Alignments were realigned around indels, bases recalibrated for platform and experiment-specific covariates, then used for variant calling and recalibration. We used a modified G-test to detect allele frequency shifts in the two replicate F2 populations. Variants exceeding a false discovery rate threshold were used to identify candidate genes that were common to the two replicates in order to identify biological processes relevant to CCR. These candidates were compared to results from a parallel association mapping experiment using the Drosophila Genetic Reference Panel.