Drosophila melanogaster selected for resistance to desiccation (no food or water) display slower development and a higher body mass compared to fed controls due to an extended third larval instar. I hypothesize that desiccation selected D. melanogaster larvae will have a different gene expression profile compared to fed controls. Separate populations of D. melanogaster were subjected to desiccation (no food or water), starvation (no food) until 80-85% mortality, for 75 generations. mRNA from the larval fat body was collected at 88 hours, 96 hours, 112 hours and 120 hours post-hatching. Four replicate samples were used for each condition and time point. Gene expression was measured using two color cDNA microarrays. I analyzed the microarray data using a two-way factorial design ANOVA implemented in R using a significance level of 0.05 with FDR correction. The FDR adjusted results showed 43 genes differentially expressed for selection condition, 4590 genes for time, and 122 for selection by time (interaction). I then used DAVID 6.7 to explore which biological pathways are over-represented for these genes. One biological process was shown to be over-represented for the selection genes, 67 for time, and 10 for interaction. These over-represented processes suggest desiccation selected and control populations are indeed developing differently
