Postglacial migration and the loss of allozyme variation in northern populations of Asclepias exaltata (Asclepiadaceae)
Postglacial migration and the loss of allozyme variation in northern populations of Asclepias exaltata (Asclepiadaceae)
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DOI：
10.2307/2446342
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发表时间：
1998-08-01
影响因子：
3
通讯作者：
Broyles, SB
中科院分区：
文献类型：
--
作者：
Broyles, SB
最近的威斯康星州冰川提供了机会，研究冰后期冰川化对植物和动物群落的群体遗传学的影响。在这项研究中，等位酶的变化进行了研究，在19个种群的草本多年生萝摩exaltata发生在以前的冰川地区的北美。这些北方的A. exaltata具有显着较少的多态位点（46.3 +/-2.7;平均值+/-1 SD），每个多态位点的等位基因（1.84 +/-0.24），和预期的杂合性（0.133 +/-0.031）比在阿巴拉契亚山脉南部的更新世避难所发现的人口。居群水平等位酶多样性从南到北、从东到西呈线性递减。19个罕见的等位基因先前观察到在南部阿巴拉契亚人群中未检测到在北方地区。7个常见等位基因的等位基因频率有明显的变化。其中，只有Pgd-1a和Mnr-1c在阿巴拉契亚山脉南部的频率较低，并分别随着纬度和经度的增加而显著增加。尽管这种等位酶多样性的损失后，冰后期迁移，北方人口的A。exaltata的等位酶多样性高于其它长寿多年生草本植物，而种群分化程度低于其它长寿多年生草本植物（G（ST）= 0.117）。北方地区栖息地破碎化的增加和阿巴拉契亚山脉南部栖息地的潜在丧失，可能会减少历史上丰富的基因库，为冰后期恢复提供遗传资源。
The recent Wisconsin glaciation has provided opportunities for examining the effects of postglacial recolonization on the population genetics of plant and animal communities. In this study allozyme variation was examined in 19 populations of the herbaceous perennial Asclepias exaltata occurring in previously glaciated regions of North America. These northern populations of A. exaltata possess significantly fewer polymorphic loci (46.3 +/- 2.7; mean +/- 1 SD), alleles per polymorphic locus (1.84 +/- 0.24), and expected heterozygosity (0.133 +/- 0.031) than populations found in the Pleistocene refugium in the southern Appalachians. Population-level allozyme diversity decreased linearly from south to north and from east to west. Nineteen uncommon alleles previously observed in southern Appalachian populations were undetected in the northern region. Seven common alleles exhibited a clinal change in allele frequency. Of these, only Pgd-1a and Mnr-1c were at low-frequency in the southern Appalachians and increased significantly with increasing latitude and longitude, respectively. Despite this loss of allozyme diversity following postglacial migration, northern populations of A. exaltata have higher allozyme diversity and lower population differentiation (G(ST) = 0.117) than mean values for other long-lived herbaceous perennials. Increased habitat fragmentation in northern regions and potential habitat loss in the southern Appalachians are likely to reduce the historically rich gene pool that has provided the genetic stock for postglacial recoveries.