Fine-scale population epigenetic structure in relation to gastro-intestinal parasite load in red grouse (Lagopus lagopus scotica)

Epigenetic modification of cytosine methylation states can be elicited by environmental stresses and may be a key process affecting phenotypic plasticity and adaptation. Parasites are potent stressors with profound physiological and ecological effects on their host, but there is little understanding in how parasites may influence host methylation states. Here, we estimate epigenetic diversity and differentiation among 21 populations of red grouse (Lagopus lagopus scotica) in north-east Scotland, and test for association of gastro-intestinal parasite load (caecal nematode Trichostrongylus tenuis) with hepatic genome-wide and locus-specific methylation states. Following methylation-sensitive AFLP (MSAP), 129 bands, representing 73 methylation-susceptible and 56 non-methylated epiloci, were scored across 234 individuals. The populations differed significantly in genome-wide methylation levels and were also significantly epigenetically (FST = 0.0227; p &lt; 0.001) and genetically (FST = 0.0...胞嘧啶甲基化状态（cytosine methylation states）的表观遗传修饰（epigenetic modification）可由环境胁迫诱导，或许是影响表型可塑性（phenotypic plasticity）与适应性（adaptation）的关键过程。寄生虫（parasites）是一类强效胁迫因子，对宿主（host）具有深远的生理与生态效应，但目前学界对寄生虫如何调控宿主甲基化状态的认知仍较为有限。本研究对苏格兰东北部21个红松鸡（*Lagopus lagopus scotica*）种群的表观遗传多样性与分化水平进行评估，并检验胃肠道寄生虫负荷（gastro-intestinal parasite load）——即盲肠线虫细刺毛圆线虫（*Trichostrongylus tenuis*）——与宿主肝脏全基因组及位点特异性甲基化状态之间的关联。经甲基化敏感扩增多态性（methylation-sensitive AFLP，MSAP）实验分型后，研究在234个受试个体中共获得129个条带，其中73个为易受甲基化影响的表观位点（methylation-susceptible epiloci），56个为非甲基化表观位点（non-methylated epiloci）。结果显示，各种群的全基因组甲基化水平存在显著差异，且在表观遗传层面（FST = 0.0227; p < 0.001）与遗传层面（FST = 0.0…）均达到显著分化水平。