title: Effects of temperature on transcriptome and cuticular hydrocarbon expression in ecologically differentiated populations of desertDrosophila.
abstract: We assessed the effects of temperature differences on gene expression using whole-transcriptome microarrays and cuticular hydrocarbon variation in populations of cactophilicDrosophila mojavensis. Four populations from Baja California and mainland Mexico and Arizona were each reared on two different host cacti, reared to sexual maturity on laboratory media, and adults were exposed for 12 hr to 15, 25, or 35°C. Temperature differences influenced the expression of 3,294 genes, while population differences and host plants affected >2,400 each in adult flies. Enriched, functionally related groups of genes whose expression changed at high temperatures included heat response genes, as well as genes affecting chromatin structure. Gene expression differences between mainland and peninsular populations included genes involved in metabolism of secondary compounds, mitochondrial activity, and tRNA synthases. Flies reared on the ancestral host plant, pitaya agria cactus, showed upregulation of genes involved in metabolism, while flies reared on organ pipe cactus had higher expression of DNA repair and chromatin remodeling genes. Population × environment (G × E) interactions had widespread effects on the transcriptome where population × temperature interactions affected the expression of >5,000 orthologs, and there were >4,000 orthologs that showed temperature × host plant interactions. Adults exposed to 35°C had lower amounts of most cuticular hydrocarbons than those exposed to 15 or 25°C, including abundant unsaturated alkadienes. For insects adapted to different host plants and climatic regimes, our results suggest that temperature shifts associated with climate change have large and significant effects on transcriptomes of genetically differentiated natural populations.
authors.affiliation: Program in Ecology and Evolutionary Biology Department of Biological Sciences University of Arkansas Fayetteville AR 72701 USA.
authors.forename: William J
authors.initials: WJ
authors.lastname: Etges
authors.affiliation: Program in Ecology and Evolutionary Biology Department of Biological Sciences University of Arkansas Fayetteville AR 72701 USA; Present address: Math and Science Division Lyon College Batesville AR 72501 USA.
authors.forename: Cássia C
authors.initials: CC
authors.lastname: de Oliveira
authors.affiliation: School of Life Sciences University of Nevada Las Vegas NV 89919 USA; Present address: Department of Biology University of Pennsylvania Philadelphia PA 19104 USA.
authors.forename: Subhash
authors.initials: S
authors.lastname: Rajpurohit
authors.affiliation: School of Life Sciences University of Nevada Las Vegas NV 89919 USA.
authors.forename: Allen G
authors.initials: AG
authors.lastname: Gibbs
keywords: adaptation; climate change; desert; gene expression; host cactus; temperature