Population transcriptomics of cactus host shifts in Drosophila mojavensis

In the presence of environmental change, natural selection can shape the transcriptome. Under a scenario of environmental change, genotypes that are better able to modulate gene expression to maximize fitness will tend to be favored. Therefore, it is important to examine gene expression at the population level in order to distinguish random or neutral gene expression variation from the pattern produced by natural selection. This study investigates the natural variation in transcriptional response to a cactus host shift utilizing the mainland Sonora population of Drosophila mojavensis. Drosophila mojavensis is a cactophilic species composed of four cactus host populations endemic to the deserts of North America. Overall, the change in cactus host was associated with a significant reduction in larval viability, as well as the differential expression of 21% of the genome (3,109 genes). Among the genes identified were a set of genes previously known to be involved in xenobiotic metabolism, as well as genes involved in cellular energy production, oxidoreductase/carbohydrate metabolism, structural components and mRNA binding. Interestingly, of the 3,109 genes whose expression was affected by host use, there was a significant overrepresentation of genes that lacked an orthologous call to the D. melanogaster genome, suggesting the possibility of an accelerated rate of evolution in these genes. Of the genes with a significant cactus effect, the majority, 2,264 genes, did not exhibit a significant cactus-by-line interaction. This population level approach facilitated the identification of genes involved in past cactus host shifts. Dataset from Population transcriptomics of cactus host shifts in Drosophila mojavensis, Matzkin, LM. Molecular Ecology. Nine isofemale lines of Drosophila mojavensis from the Sonoran cactus host race were utilized. Each line was reared in either their native host (necrotic organpipe cactus) or an alternative host (necrotic agria cactus). For each line, two replicates were done for a grand total of 36 hybridizations.