Mitochondrial genotype influences the response to cold stress in the European green crab Carcinus maenas

Hybrid zones provide natural experiments in recombination within and between genomes that may have strong effects on organismal fitness. On the East Coast of North America, two distinct lineages of the European green crab (Carcinus maenas) have been introduced in the last two centuries. These two lineages with putatively different adaptive properties have hybridized along the coast of the eastern Gulf of Maine, producing new nuclear and mitochondrial combinations that show clinal variation correlated with water temperature. To test the hypothesis that mitochondrial or nuclear genes have effects on thermal tolerance, we first measured the response to cold stress in crabs collected throughout the hybrid zone, then sequenced the mitochondrial CO1 gene and two nuclear SNPs representative of nuclear genetic lineage. Mitochondrial haplotype had a strong association with the ability of crabs to right themselves at 4.5 &[deg]C that was sex specific: haplotypes originally from northern Europ...杂交带为基因组内部及基因组间的重组提供了天然实验体系，此类重组可对生物体适合度产生显著影响。近两个世纪以来，两个分化显著的欧洲绿蟹（Carcinus maenas）谱系已被引入北美东海岸。这两个具备潜在不同适应性特征的谱系，在缅因湾东部沿岸发生杂交，产生了全新的核基因与线粒体基因组合，此类组合呈现出与水温相关的梯度变异模式。为验证线粒体或核基因对热耐受性存在影响这一假说，我们首先对采集自整个杂交带的欧洲绿蟹开展冷应激响应测定，随后对线粒体CO1基因以及两个可代表核遗传谱系的核单核苷酸多态性（Single Nucleotide Polymorphism，SNP）位点进行了测序。结果显示，线粒体单倍型与螃蟹在4.5℃条件下的翻正能力存在显著关联，且该关联具有性别特异性：源自北欧的单倍型……