Martínková Natália, McDonald Robbie A, Searle Jeremy B
Department of Biology, University of York, PO Box 373, York YO10 5YW, UK.
Proc Biol Sci. 2007 Jun 7;274(1616):1387-93. doi: 10.1098/rspb.2007.0334.
The current Irish biota has controversial origins. Ireland was largely covered by ice at the Last Glacial Maximum (LGM) and may not have had land connections to continental Europe and Britain thereafter. Given the potential difficulty for terrestrial species to colonize Ireland except by human introduction, we investigated the stoat (Mustela erminea) as a possible cold-tolerant model species for natural colonization of Ireland at the LGM itself. The stoat currently lives in Ireland and Britain and across much of the Holarctic region including the high Arctic. We studied mitochondrial DNA variation (1771 bp) over the whole geographical range of the stoat (186 individuals and 142 localities), but with particular emphasis on the British Isles and continental Europe. Irish stoats showed considerably greater nucleotide and haplotype diversity than those in Britain. Bayesian dating is consistent with an LGM colonization of Ireland and suggests that Britain was colonized later. This later colonization probably reflects a replacement event, which can explain why Irish and British stoats belong to different mitochondrial lineages as well as different morphologically defined subspecies. The molecular data strongly indicate that stoats colonized Ireland naturally and that their genetic variability reflects accumulation of mutations during a population expansion on the island.
当前爱尔兰的生物区系起源存在争议。在末次盛冰期（LGM）时，爱尔兰大部分地区被冰覆盖，此后可能与欧洲大陆和英国没有陆地连接。鉴于陆地物种除了通过人类引入外很难在爱尔兰殖民，我们研究了白鼬（Mustela erminea），将其作为末次盛冰期时自然殖民爱尔兰的一种可能的耐寒模式物种。白鼬目前生活在爱尔兰、英国以及包括高北极地区在内的大部分全北区。我们研究了白鼬整个地理分布范围内（186个个体和142个地点）的线粒体DNA变异（1771 bp），尤其着重于不列颠群岛和欧洲大陆。爱尔兰白鼬的核苷酸和单倍型多样性明显高于英国的白鼬。贝叶斯定年法与末次盛冰期时白鼬对爱尔兰的殖民情况相符，并表明英国是后来才被殖民的。这种后来的殖民可能反映了一次替代事件，这可以解释为什么爱尔兰和英国的白鼬属于不同的线粒体谱系以及不同的形态学定义亚种。分子数据有力地表明白鼬是自然殖民爱尔兰的，并且它们的遗传变异性反映了在该岛种群扩张期间突变的积累。
