[M-IS23] Mountain Science

[MIS23-14] The role of mountains in the creation of biodiversity

★Invited Papers

*Tomoya Suzuki¹, Koji Tojo^1,2 (1.Faculty of Science, Shinshu University, 2.Institute of Mountain Science, Shinshu University)

Keywords:Phylogeography, Biodiversity, Genetic diversity

Elucidation of the creation process of biodiversity is one of the most important tasks in biology. The mountain region is one of the suitable fields for elucidating the factors contributing to the creation of biodiversity. Because many organisms which are adapted to severe mountain environments (e.g., low temperature, strong winds, and strong ultraviolet rays), are distributed in mountainous regions. In particular, organisms which are exclusively adapted to alpine zones are not capable of migration via low elevation areas. Because of such a situation, there are some cases in which similar adaptation within alpine zone environments occurs in seperate mountainous areas independently. We have studied such a case using the scorpionfly Panorpodes paradoxa (Mecoptera, Panorpodidae), which are distributed from the mountain zone to the alpine zone. In this species, it is reported that the short-winged type female (i.e., alpine type) is observable in the alpine to the subalpine zone, and the long-winged type (i.e., general type) is observable in the elevational region blow the alpine type’s distribution range. In addition, it has been suggested that these two types constitute distinct species. From the above situation, we conducted molecular phylogenetic analyses using mtDNA and nDNA data sets from the Japanese Panorpodes species in order to estimate their evolutionary history. The molecular phylogenetic analyses’ results suggested that the parallel evolution of the alpine type from the general type occurred at least two times independently in different mountain regions. Therefore, our results indicate that the alpine type is an “ecomorph”, which adapted to the high elevation region environment. As mentioned above, mountains are an important environment in that they promote the adaptive radiation of organisms. In addition, mountains have one more important function in the creation of biodiversity, their function as geographic barriers. There are some cases in which a population of organisms which are distributed in low elevation regions, become divided by the formation of high elevation mountains. Thereby, the gene flow between the resulting divided populations is restricted, thereby promoting genetic differentiation between the populations. From this viewpoint, we focused on two East Asian giant water bugs, Appasus japonicus and Appasus major (Heteroptera, Belostomatidae), and conducted their molecular phylogenetic analyses. They are distributed in lowland lentic habitats, and it is considered that mountains act as a geographic barrier between them. As a result, A. japonicusand A. major were divided into two and three genetic lineages in the Japanese Archipelago respectively. And the boundary regions between their separated genetic lineages are the Chugoku Mountains for A. japonicus, and the Ou Mountains and the Central Mountainous Area of Japan for A. major. Furthermore, we conducted fine-scale molecular phylogenetic analyses in the boundary regions of each genetic lineage. Thereby we found a secondary contact zone between the primary differentiated genetic lineages in the Sanyo region (Hiroshima and Yamaguchi Prefectures) for A. japonicus, and also their secondary contact zones in Aomori, Niigata and Fukushima Prefectures for A. major. It is considered that these instances of secondary contact of previously differentiated genetic lineages are very important events for the creation and preservation of the genetic diversity of organisms. Our results of the molecular phylogenetic analyses of these two East Asian giant water bugs suggested that mountains have had a very important function in the creation and preservation of intra-specific genetic diversity. In conclusion, our study indicated that mountain areas are critical environments being deeply related to the creation of various levels of biodiversity.