School of Biological Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, Northern Ireland.
BMC Evol Biol. 2011 Jan 27;11:29. doi: 10.1186/1471-2148-11-29.
The aim of the present study was to use a combined phylogeographic and species distribution modelling approach to compare the glacial histories of two plant species with overlapping distributions, Orthilia secunda (one-sided wintergreen) and Monotropa hypopitys (yellow bird's nest). Phylogeographic analysis was carried out to determine the distribution of genetic variation across the range of each species and to test whether both correspond to the "classic" model of high diversity in the south, with decreasing diversity at higher latitudes, or whether the cold-adapted O. secunda might retain more genetic variation in northern populations. In addition, projected species distributions based on a future climate scenario were modelled to assess how changes in the species ranges might impact on total intraspecific diversity in both cases.
Palaeodistribution modelling and phylogeographic analysis using multiple genetic markers (chloroplast trnS-trnG region, nuclear ITS and microsatellites for O. secunda; chloroplast rps2, nuclear ITS and microsatellites for M. hypopitys) indicated that both species persisted throughout the Last Glacial Maximum in southern refugia. For both species, the majority of the genetic diversity was concentrated in these southerly populations, whereas those in recolonized areas generally exhibited lower levels of diversity, particularly in M. hypopitys. Species distribution modelling based on projected future climate indicated substantial changes in the ranges of both species, with a loss of southern and central populations, and a potential northward expansion for the temperate M. hypopitys.
Both Orthilia secunda and Monotropa hypopitys appear to have persisted through the LGM in Europe in southern refugia. The boreal O. secunda, however, has retained a larger proportion of its genetic diversity in more northerly populations outside these refugial areas than the temperate M. hypopitys. Given that future species distribution modelling suggests northern range shifts and loss of suitable habitat in the southern parts of the species' current distributions, extinction of genetically diverse rear edge populations could have a significant effect in the rangewide intraspecific diversity of both species, but particularly in M. hypopitys.
本研究旨在采用综合系统地理学和物种分布模型方法，比较两种分布范围重叠的植物种——单侧冬绿（Orthilia secunda）和黄鸟巢（Monotropa hypopitys）的冰川历史。系统地理学分析用于确定每个物种的遗传变异在其分布范围内的分布，并检验它们是否都符合高多样性的“经典”模式，即在南部地区多样性较高，而在较高纬度地区多样性降低，或者耐寒的 O. secunda 是否可能在北部种群中保留更多的遗传变异。此外，还根据未来气候情景对物种分布进行了预测模型，以评估这两种情况下物种分布范围的变化如何影响种内总多样性。
古分布模型和基于多种遗传标记（单侧冬绿的叶绿体 trnS-trnG 区、核 ITS 和微卫星；黄鸟巢的叶绿体 rps2、核 ITS 和微卫星）的系统地理学分析表明，这两个物种在末次冰盛期都在南部避难所中生存下来。对于这两个物种，大多数遗传多样性都集中在这些南部种群中，而在再定居地区的种群通常表现出较低的多样性，特别是在 M. hypopitys 中。基于未来预测气候的物种分布模型表明，这两个物种的分布范围都发生了重大变化，南部和中部的种群将会减少，而温带的 M. hypopitys 则可能向北扩张。
单侧冬绿和黄鸟巢似乎都在欧洲南部避难所的末次冰期冰盛期幸存下来。然而，与温带的 M. hypopitys 相比，北方的 O. secunda 在这些避难区以外的更北的种群中保留了更大比例的遗传多样性。鉴于未来的物种分布模型表明，物种的北部范围将会发生变化，而其当前分布南部地区的适宜栖息地将会减少，遗传多样性丰富的后缘种群灭绝可能会对这两个物种的种内广泛多样性产生重大影响，但对 M. hypopitys 的影响尤其大。
