Department of Zoology, University of Otago, PO Box 56, Dunedin, New Zealand.
Evolution. 2010 Jul;64(7):2033-43. doi: 10.1111/j.1558-5646.2010.00980.x. Epub 2010 Feb 19.
The origin of the New Zealand "beech gap," a low-diversity zone in the central South Island corresponding with a disjunction in the distribution of many taxa, has been the focus of biogeographical debate for many decades. Here, we use comparative phylogeographic analysis (COI; H3) of six alpine stonefly genera (116 individuals, 102 localities) to test a vicariant evolutionary hypothesis for the origin of this "biotic gap." We find strikingly similar phylogeographic patterns in all six genera, with the deepest genetic divergences always found between samples north and south of the beech gap. The magnitude of north-south genetic differentiation for COI is similar across all six genera (ranging from 0.074 to 0.091), with a test for simultaneous vicariance confirming that divergence is consistent with a single evolutionary event. The concordant cladogenesis detected across multiple taxa is consistent with vicariant isolation caused by the onset of glaciation in the late Pliocene. This study thus indicates an important cladogenetic role for glaciation, an abiotic evolutionary process that is more typically associated with loss of biodiversity.
新西兰“山毛榉缺口”是南岛中部一个低多样性区域，与许多分类群的分布不连续相对应，几十年来一直是生物地理辩论的焦点。在这里，我们使用比较系统地理学分析（COI；H3）对六个高山石蝇属（116 个个体，102 个地点）进行测试，以检验这种“生物缺口”起源的分歧进化假说。我们发现所有六个属的系统地理模式都非常相似，在山毛榉缺口南北的样本之间总是存在最深的遗传分歧。COI 的南北遗传分化程度在所有六个属中都相似（范围从 0.074 到 0.091），同时进行的分歧测试证实，这种分化与单一进化事件一致。在多个分类群中检测到的一致的分支发生与上新世晚期冰川作用引起的分歧隔离一致。因此，这项研究表明，冰川作用在生物进化中起着重要的作用，而冰川作用是一种通常与生物多样性丧失相关的非生物进化过程。
