Data from: Gene expression under thermal stress varies across a geographic range expansion front

Many ectothermic species are currently expanding their distributions polewards due to anthropogenic global warming. Molecular genetic mechanisms facilitating range expansion under these conditions are largely unknown, but understanding these could help mitigate expanding pests and disease vectors, or help explain why some species fail to track changing climates. Here, using RNA-seq data, we examine genome-wide changes in gene expression under heat and cold stress in the range-expanding damselfly Ischnura elegans in northern Europe. We find that both the number of genes involved and levels of gene expression under heat stress have become attenuated during the expansion, consistent with a previously-reported release from selection on heat tolerances as species move polewards. Genes upregulated under cold stress differed between core and edge populations, corroborating previously-reported rapid adaptation to cooler climates at the expansion front. Expression of sixty-nine genes exhibited a region x treatment effect; these were primarily upregulated in response to heat stress in core populations but in response to cold stress at the range edge, suggesting that some cellular responses originally adapted to heat stress may switch to cold stress functionality upon encountering novel thermal selection regimes during range expansion. Transcriptional responses to thermal stress involving heat shock and neural function genes were largely geographically conserved, while retrotransposon, regulatory, muscle function and defence gene expression patterns were more variable. Flexible mechanisms of cold stress response and the ability of some genes to shift their function between heat and cold stress might be key mechanisms facilitating rapid poleward expansion in insects.

Usage Notes
AssemblyThe file contains fasta sequence of high quality transcripts obtained after three step of stringent filtering.annotationsThe file contains annotations for high quality transcripts by BLASTX, InterProScan, GO and Enzymes terms.RSEM.tarThe folder contains RSEM output files for each sample.differential_expression.tarThe folder contains files for differential expression analysis between heat and cold treatments from two regions (hoje and nora).

众多变温物种因人类活动导致的全球变暖而正向极地扩张其分布范围。在这些条件下促进物种范围扩张的分子遗传机制尚鲜为人知，但对其了解有助于减轻蔓延的害虫和疾病传播媒介，或有助于解释为何某些物种无法追踪气候的变化。本研究中，利用RNA-seq数据，我们分析了在北部欧洲范围扩张的蜻蜓Ischnura elegans在热和冷胁迫下的全基因组基因表达变化。我们发现，在扩张过程中，涉及基因的数量以及热胁迫下的基因表达水平均有所降低，这与先前报道的物种向极地迁移时对热耐受性选择的释放相一致。在冷胁迫下上调的基因在核心种群和边缘种群之间存在差异，证实了先前报道的物种在扩张前沿对较冷气候的快速适应。在六十多个基因的表达中观察到区域与处理效应；这些基因主要在核心种群对热胁迫做出上调反应，但在范围边缘对冷胁迫做出反应，这表明一些原本适应热胁迫的细胞反应可能在范围扩张过程中遇到新的热选择机制时转变为冷胁迫功能。涉及热休克和神经功能基因的热胁迫转录反应在地理上大致保持一致，而逆转录转座子、调控、肌肉功能和防御基因的表达模式则更为多变。灵活的冷胁迫响应机制以及某些基因在热和冷胁迫之间转换其功能的能力可能是昆虫快速向极地扩张的关键机制。

使用说明

汇编：该文件包含经过三步严格筛选获得的高质量转录本fasta序列。
注释：该文件包含由BLASTX、InterProScan、GO和酶术语注释的高质量转录本。
RSEM.tar：该文件夹包含每个样本的RSEM输出文件。
differential_expression.tar：该文件夹包含来自两个区域（hoje和nora）的热和冷处理之间的差异表达分析文件。