Department of Biosciences P.O. Box 65, 00014 University of Helsinki Finland.
Ecol Evol. 2011 Sep;1(1):46-62. doi: 10.1002/ece3.6.
Widely distributed Palearctic insects are ideal to study phylogeographic patterns owing to their high potential to survive in many Pleistocene refugia and-after the glaciation-to recolonize vast, continuous areas. Nevertheless, such species have received little phylogeographic attention. Here, we investigated the Pleistocene refugia and subsequent postglacial colonization of the common, abundant, and widely distributed ant Myrmica rubra over most of its Palearctic area, using mitochondrial DNA (mtDNA). The western and eastern populations of M. rubra belonged predominantly to separate haplogroups, which formed a broad secondary contact zone in Central Europe. The distribution of genetic diversity and haplogroups implied that M. rubra survived the last glaciation in multiple refugia located over an extensive area from Iberia in the west to Siberia in the east, and colonized its present areas of distribution along several routes. The matrilineal genetic structure of M. rubra was probably formed during the last glaciation and subsequent postglacial expansion. Additionally, because M. rubra has two queen morphs, the obligately socially parasitic microgyne and its macrogyne host, we tested the suggested speciation of the parasite. Locally, the parasite and host usually belonged to the same haplogroup but differed in haplotype frequencies. This indicates that genetic differentiation between the morphs is a universal pattern and thus incipient, sympatric speciation of the parasite from its host is possible. If speciation is taking place, however, it is not yet visible as lineage sorting of the mtDNA between the morphs.
广泛分布的古北界昆虫是研究系统地理格局的理想对象，因为它们有很高的潜力在许多更新世避难所中生存，并在冰川消融后重新大面积连续地扩散。然而，这类物种受到的系统地理关注很少。在这里，我们利用线粒体 DNA（mtDNA）研究了常见、丰富且广泛分布的蚂蚁红火蚁在其古北界大部分地区的更新世避难所和随后的冰川后扩散。红火蚁的西部和东部种群主要属于不同的单倍型群，它们在中欧形成了一个广泛的次级接触区。遗传多样性和单倍型群的分布表明，红火蚁在多个避难所中幸存下来，这些避难所分布在从西部的伊比利亚到东部的西伯利亚的广阔区域，并且沿着几条路线扩散到其现在的分布区域。红火蚁的母系遗传结构可能是在上一次冰河期和随后的冰川后扩张过程中形成的。此外，由于红火蚁有两种蜂王形态，即强制性社会性寄生的小工蚁和其宿主大工蚁，我们测试了寄生虫的假设物种形成。在局部地区，寄生虫和宿主通常属于同一单倍型群，但在单倍型频率上有所不同。这表明形态之间的遗传分化是普遍存在的，因此寄生虫与其宿主的近缘、同域物种形成是可能的。然而，如果物种形成正在发生，那么在形态之间的 mtDNA 谱系分化中还没有显现出来。
