DNA methylation predicts immune gene expression in introduced house sparrows (Passer domesticus)

Populations undergoing range expansions are often faced with novel selective pressures, and to cope with such challenges, populations must either adapt quickly or exhibit phenotypic plasticity. This latter option allows for rapid phenotypic adjustments and persistence in novel environments, and thus could be advantageous at range‐edges. Our previous research on house sparrows in Kenya—a site of ongoing range expansion— and a growing literature suggests that invasion success is facilitated by epigenetic regulation of gene expression. Previously, we found (i) differences in the expression of a microbial surveillance gene (i.e. Toll‐like receptor 4—TLR4), and (ii) extensive variation in genome‐wide DNA methylation among house sparrows across Kenya. Here, our goal was to investigate whether these two observations are related, specifically whether DNA methylation within a target sequence upstream of the TLR4 transcription start site is associated with variation in TLR4 expression. We found t...经历范围扩张的种群通常会面临全新的选择压力，为应对这类挑战，种群要么快速适应环境，要么展现出表型可塑性（phenotypic plasticity）。后者能够实现快速的表型调整，使其在新环境中得以存续，因此在分布范围边缘可能具备演化优势。我们此前针对正在经历范围扩张的肯尼亚家麻雀开展的研究，以及日益增多的相关文献均表明，基因表达的表观遗传调控有助于提升入侵成功率。此前我们的研究发现：其一，微生物监测基因——Toll样受体4（Toll-like receptor 4，TLR4）的表达存在差异；其二，肯尼亚全境家麻雀的全基因组DNA甲基化（DNA methylation）存在广泛变异。本研究旨在探究这两项观测结果之间是否存在关联，具体而言，即TLR4转录起始位点（transcription start site）上游靶序列内的DNA甲基化是否与TLR4表达变异相关。我们发现