Data from: Functional genomic and phenotypic responses to desiccation in natural populations of a desert drosophilid

We used whole transcriptome microarrays to assess changes in gene expression and monitored mortality rates and epicuticular hydrocarbons (CHCs) in response to desiccation stress in four natural populations of Drosophila mojavensis from Baja California and mainland Mexico. Desiccation had the greatest effect on gene expression, followed by biogeographical variation at regional and population levels. Genes involved in environmental sensing and cuticular structure were up-regulated in dry conditions, while genes involved in transcription itself were down-regulated. Flies from Baja California had higher expression of reproductive and mitochondrial genes, suggesting that these populations have greater fecundity and higher metabolic rates. Host plant differences had a surprisingly minor effect on the transcriptome. In most cases, desiccation-caused mortality was greater in flies reared on fermenting cactus tissues than laboratory media. Water content of adult females and males was significantly different, and was lower in Baja California males. Different groups of CHCs simultaneously increased and decreased in amounts due to desiccation exposure of 9 and 18 hr and were population-specific and dependent on larval rearing substrates. Overall, we observed that changes in gene expression involved a coordinated response of metabolic, behavioral, and cuticular genes. Together with differential expression of cuticular hydrocarbons, this study revealed some of the mechanisms that have allowed D. mojavensis to exploit its harsh desert conditions. Certainly, for D. mojavensis that uses different host plants, population-level understanding of responses to stressors associated with future climate change in desert regions must be evaluated across geographical and local ecological scales.

本研究采用全转录组芯片检测基因表达变化，并监测了下加利福尼亚半岛与墨西哥本土的4个莫哈韦果蝇(Drosophila mojavensis)自然种群在干旱胁迫下的死亡率与表皮碳氢化合物(epicuticular hydrocarbons, CHCs)水平。干旱胁迫对基因表达的影响最为显著，其次是区域与种群水平的生物地理变异。干旱环境下，参与环境感知与表皮结构构建的基因表达上调，而参与转录过程本身的基因则表达下调。下加利福尼亚半岛的莫哈韦果蝇种群的生殖相关基因与线粒体基因表达水平更高，这暗示该种群具有更强的繁殖力与更高的代谢速率。寄主植物差异对转录组的影响出人意料地微弱。多数情况下，在发酵仙人掌组织中饲养的果蝇比在实验室培养基中饲养的果蝇更易因干旱胁迫死亡。成年雌雄果蝇的含水量存在显著差异，且下加利福尼亚半岛种群的雄性果蝇含水量更低。经过9小时与18小时的干旱胁迫处理后，不同组分的表皮碳氢化合物(CHCs)的含量同时出现升高与降低，且该变化具有种群特异性，并受幼虫饲养基质的影响。总体而言，本研究发现基因表达的变化涉及代谢、行为与表皮相关基因的协同响应。结合表皮碳氢化合物的差异表达，本研究揭示了莫哈韦果蝇适应严苛沙漠环境的部分机制。对于依赖不同寄主植物的莫哈韦果蝇而言，未来需在地理与局地生态尺度上开展研究，以明确种群水平对沙漠区域未来气候变化相关胁迫因子的响应机制。