ABSTRACT

Anthropogenic pollution is known to negatively influence an organism’s physiology, behaviour, and fitness. Epigenetic regulation, such as DNA methylation, has been hypothesized as a potential mechanism to mediate such effects, yet studies in wild species are lacking. We first investigated the effects of early-life exposure to the heavy metal lead (Pb) on DNA methylation levels in a wild population of great tits (Parus major), by experimentally exposing nestlings to Pb at environmentally relevant levels. Secondly, we compared nestling DNA methylation from a population exposed to long-term heavy metal pollution (close to a copper smelter), where birds suffer from pollution-related decrease in food quality, and a control population. For both comparisons, the analysis of about one million CpGs covering most of the annotated genes revealed that pollution-related changes in DNA methylation were not genome wide, but enriched for genes underlying developmental processes. However, the results were not consistent when using binomial or beta binomial regression highlighting the difficulty of modelling variance in CpGs. Our study indicates that post-natal anthropogenic heavy metal exposure can affect methylation levels of development related genes in a wild bird population.

摘要

众所周知，人为污染会对生物体的生理、行为和健康产生负面影响。表观遗传调控，如 DNA 甲基化，已被假设为介导这种影响的潜在机制，但缺乏对野生物种的研究。我们首先研究了早期接触重金属铅 (Pb) 对野生大山雀 ( Parus major ) 种群 DNA 甲基化水平的影响。)，通过实验将雏鸟暴露在环境相关水平的铅中。其次，我们比较了长期暴露于重金属污染的人群（靠近铜冶炼厂）的雏鸟 DNA 甲基化，其中鸟类遭受与污染相关的食品质量下降，以及对照人群。对于这两种比较，对覆盖大部分注释基因的大约一百万个 CpG 的分析表明，与污染相关的 DNA 甲基化变化不是全基因组的，而是富含发育过程的基因。然而，当使用二项式或 beta 二项式回归时，结果并不一致，突出了 CpG 中建模方差的难度。我们的研究表明，出生后人为重金属暴露会影响野生鸟类种群中发育相关基因的甲基化水平。