Data from: An association between differential expression and genetic divergence in the Patagonian olive mouse (Abrothrix olivacea)

Recent molecular studies have found striking differences between desert-adapted species and model mammals regarding water conservation. In particular, aquaporin 4, a classical gene involved in water regulation of model species, is absent or not expressed in the kidneys of desert-adapted species. To further understand the molecular response to water availability we studied the Patagonian olive mouse Abrothrix olivacea, a species with an unusually broad ecological tolerance that exhibits a great urine concentration capability. The species is able to occupy both the arid Patagonian steppe and the Valdivian and Magellanic forests. We sampled 95 olive mouse specimens from four localities (two in the steppe, two in the forests) and analyzed both phenotypic variables and transcriptomic data to investigate the response of this species to the contrasting environmental conditions. The relative size of the kidney and the ratio of urine to plasma concentrations were, as expected, negatively correlated with annual rainfall. Expression analyses uncovered nearly 3,000 genes that were differentially expressed between steppe and forest samples and indicated that this species resorts to the “classical” gene pathways for water regulation. Differential expression across biomes also involves genes involved in immune and detoxification functions. Overall, genes that were differentially expressed showed a slight tendency to be more divergent and to display an excess of intermediate allele frequencies, relative to the remaining loci. Our results indicate that both differential expression in pathways involved in water conservation and geographical allelic variation are important in the occupation of contrasting habitats by the Patagonian olive mouse.

近期的分子生物学研究发现，适应沙漠环境的物种与模式哺乳动物在水分保持方面存在显著差异。其中，水通道蛋白4（aquaporin 4）是模式物种中参与水分调控的经典基因，但在适应沙漠环境的物种肾脏中却不存在或未表达。为进一步阐明物种对水分可利用性的分子响应机制，我们以巴塔哥尼亚橄榄鼠（Abrothrix olivacea）为研究对象——该物种拥有异常宽泛的生态耐受范围，并具备极强的尿液浓缩能力。该物种可同时栖息于干旱的巴塔哥尼亚草原以及瓦尔迪维亚和麦哲伦雨林中。我们从4个采样点（草原与森林各2个）采集了95份巴塔哥尼亚橄榄鼠标本，并通过分析表型变量与转录组数据，探究该物种对迥异环境条件的响应机制。如预期一致，肾脏相对大小与尿液-血浆浓度比值均与年降雨量呈负相关关系。表达分析结果显示，草原与森林样本间存在近3000个差异表达基因，且表明该物种通过经典基因通路实现水分调控。不同生物群落间的差异表达基因还涵盖了参与免疫与解毒功能的基因。整体而言，相较于其余基因座，差异表达基因呈现出更高的序列分化倾向，且等位基因频率分布中中间频率等位基因占比更高。本研究结果表明，水分保持相关通路的差异表达与地理等位基因变异，均在巴塔哥尼亚橄榄鼠适应迥异生境的过程中发挥了重要作用。