Phylogeny and Phylogeography of Myrmica rubra

We investigated the genetic diversification of the mountain ant, Myrmica kotokui, in the Japanese Alps by using molecular phylogenetic analyses. Myrmica kotokui is widely distributed in Japan, and in the central Japanese Alps it is found only between elevations of approximately 1000 to 2000 m. We hypothesized that genetically distinct clades of this ant species might inhabit different mountain ranges in central Japan. To test this hypothesis, we reconstructed a molecular phylogeny using the DNA sequences of the mitochondrial cytochrome oxidase I gene and the nuclear long-wavelength rhodopsin gene of M. kotokui specimens collected from six mountain ranges in the Japanese Alps. The phylogeny showed four highly differentiated clades. However, the correspondence between the clades and morphological species was a little confusing. Two clades were composed only of M. kotokui specimens, whereas the other two clades were composed of multispecies, suggesting the possibility of multispecies composition of putative M. kotokui. The distribution pattern of these clades did not support our hypothesis of geographical differentiation, because two were distributed across all ranges, and a third was distributed in five of the six ranges. On the other hand, we found a pattern in the altitudinal distribution of the clades: one clade was distributed only at higher elevations, and the others were distributed at lower elevations. Thus, the ant clades do not show geographical segregation by mountain range, but they do show altitudinal differences