Somervuo Panu, Kvist Jouni, Ikonen Suvi, Auvinen Petri, Paulin Lars, Koskinen Patrik, Holm Liisa, Taipale Minna, Duplouy Anne, Ruokolainen Annukka, Saarnio Suvi, Sirén Jukka, Kohonen Jukka, Corander Jukka, Frilander Mikko J, Ahola Virpi, Hanski Ilkka
Department of Biosciences, University of Helsinki, Helsinki, Finland; Institute of Biotechnology, Genome Biology Program, University of Helsinki, Helsinki, Finland.
Lammi Biological Station, University of Helsinki, Lammi, Finland.
PLoS One. 2014 Jul 2;9(7):e101467. doi: 10.1371/journal.pone.0101467. eCollection 2014.
We characterize allelic and gene expression variation between populations of the Glanville fritillary butterfly (Melitaea cinxia) from two fragmented and two continuous landscapes in northern Europe. The populations exhibit significant differences in their life history traits, e.g. butterflies from fragmented landscapes have higher flight metabolic rate and dispersal rate in the field, and higher larval growth rate, than butterflies from continuous landscapes. In fragmented landscapes, local populations are small and have a high risk of local extinction, and hence the long-term persistence at the landscape level is based on frequent re-colonization of vacant habitat patches, which is predicted to select for increased dispersal rate. Using RNA-seq data and a common garden experiment, we found that a large number of genes (1,841) were differentially expressed between the landscape types. Hexamerin genes, the expression of which has previously been shown to have high heritability and which correlate strongly with larval development time in the Glanville fritillary, had higher expression in fragmented than continuous landscapes. Genes that were more highly expressed in butterflies from newly-established than old local populations within a fragmented landscape were also more highly expressed, at the landscape level, in fragmented than continuous landscapes. This result suggests that recurrent extinctions and re-colonizations in fragmented landscapes select a for specific expression profile. Genes that were significantly up-regulated following an experimental flight treatment had higher basal expression in fragmented landscapes, indicating that these butterflies are genetically primed for frequent flight. Active flight causes oxidative stress, but butterflies from fragmented landscapes were more tolerant of hypoxia. We conclude that differences in gene expression between the landscape types reflect genomic adaptations to landscape fragmentation.
我们对来自北欧两个破碎景观区域和两个连续景观区域的格兰维尔豹纹蝶（Melitaea cinxia）种群之间的等位基因和基因表达变异进行了表征。这些种群在生活史特征方面存在显著差异，例如，来自破碎景观区域的蝴蝶在野外具有更高的飞行代谢率和扩散率，以及更高的幼虫生长率，相比来自连续景观区域的蝴蝶。在破碎景观中，当地种群规模较小且面临较高的局部灭绝风险，因此在景观层面的长期存续依赖于对空置栖息地斑块的频繁重新定殖，这预计会促使扩散率增加。通过RNA测序数据和一个共同花园实验，我们发现大量基因（1841个）在不同景观类型之间存在差异表达。六聚蛋白基因，其表达先前已被证明具有高遗传性，并且与格兰维尔豹纹蝶的幼虫发育时间密切相关，在破碎景观中的表达高于连续景观。在破碎景观中，相较于旧的当地种群，新建立的当地种群中的蝴蝶中表达更高的基因，在景观层面上，在破碎景观中的表达也高于连续景观。这一结果表明，破碎景观中的反复灭绝和重新定殖选择了特定的表达谱。在实验性飞行处理后显著上调的基因在破碎景观中具有更高的基础表达，表明这些蝴蝶在基因上为频繁飞行做好了准备。活跃飞行会导致氧化应激，但来自破碎景观的蝴蝶对缺氧更具耐受性。我们得出结论，不同景观类型之间的基因表达差异反映了基因组对景观破碎化的适应性。
