Exploring Evolutionary History of Animals in terms of Genetic Diversity
Ryuichi Masuda , Professor
Faculty of Science, Graduate School of Science (Department of Biological Sciences, School of Science (Area of expertise: Biology))
High school : Gifu Prefectural Seki High School
Academic background : Graduate School of Science, Hokkaido University
- Research areas
- Zoogeography, Molecular Phylogenetics
- Research keywords
- Biodiversity, Evolutionary Biology, Molecular Phylogeny, Ancient DNA, Brown Bear Study
What is the Goal of Your Research?
My field of research is zoogeography. The origin of zoogeography comes from the simple question, "where and what kind of animals are there?" As a method of the research, DNA molecular phylogeny is used. DNA, which constitutes genes, is conservative material and hard to change because it has genetic information that is transmitted from parents to children. On the other hand, accumulation of slight changes of DNA during a long time over generations has created today’s biodiversity. In molecular phylogeny, differences between species, populations and individuals (called evolutionary distance) are measured by using genetic information drawn on DNA as a measurement standard. As a result of combining this new molecular phylogeny with classical zoogeography, the field of “molecular phylogeography” has emerged. My dream is to create a world map that shows the history of animal migration, using a method of this molecular phylogeography.
What Kind of Animals have You Researched?
Research on migration history of brown bears
Triple structure of brown bears in Hokkaido based on mitochondrial DNA
I focus on mammals among all animals. This is because I have liked mammals since my childhood. I think that researching the distributional history of Japanese mammal species and populations, which have been isolated in islands and have become endemic, may lead to discovering the formation mechanism of living species (speciation).
We have investigated several kinds of mammals. Among them, one of the particularly interesting species is the brown bear in Hokkaido. As a result of the brown bear research across Hokkaido using mitochondrial DNA, which is maternally inherited, as a measurement standard, a great difference was found between subpopulations in southern, north-central and eastern Hokkaido. We named this fact "the triple structure of brown bears in Hokkaido." In addition, our comparative study with brown bears in the Eurasian Continent and North America revealed that ancestors of the brown bear in Hokkaido migrated to the island three times in the past. In this way, it was found that the brown bear in Hokkaido, which had been considered as one group (subspecies), has a history of complex migration related to change in the global environment.
Our laboratory traces the migration history of animals on a magnificent world map by decoding invisible genetic information drawn on DNA mainly with use of genetic analysis. On the other hand, I sometimes do fieldwork with students because it is important to get to know the actual habitats of animals. As a part of this fieldwork, we have overseas joint research projects with Russia and other countries to pursue the origin of Japanese animals. In some of the joint research projects, we have had to struggle with a huge number of mosquitoes and horseflies on the vast land of Siberia. The migration of animals is borderless, and therefore research of zoogeography requires interaction with researchers in countries overseas.
Thanks to the development of molecular biological technology, DNA analysis has become possible even with a very small sample, and we have introduced ancient DNA analysis with use of a fossil. In the past, we succeeded in genetic analysis of a mammoth from approximately twenty five thousand years ago that was excavated from the Siberian permafrost in a joint research project with Russia. Likewise, research on ancient DNA of brown bears from the Okhotsk culture period found on Rebun Island revealed the origin of the kumaokuri ceremony (sending a spirit in a bear to the Kingdom of God) and the intercultural exchange between the Okhotsk culture and the Epi-Jomon culture. Therefore this project has evolved into an interdisciplinary research project between departments of humanities and sciences. In this way, research using ancient DNA enables the direct research of animals from past eras, and it generates a breakthrough in zoogeography.
Invitation to Brown Bear Study
Visit to the Noboribetsu Bear Park in the general course subject "Introduction to Brown Bear Study"
We are offering a general course subject "Introduction to Brown Bear Study" for the first year students of Hokkaido University based on the latest findings of our research. In this course, students can gain a comprehensive understanding of natural history, biodiversity and cultural/social history of Hokkaido from lecturers in various fields based on the keyword "brown bear." In addition, this course includes visits to the Noboribetsu Bear Park and the Ainu Museum in Shiraoi. In addition, high school students can take part in the course.
Come and join us in the course “Introduction to Brown Bear Study” at Hokkaido University.
(1) Ryuichi Masuda and Hisashi Abe, Natural History of Zoogeography (doubutsuchirino shizenshi), Hokkaido University Press, 2005
(2) Tetsuya Amano, Ryuichi Masuda, and Tsutomu Mano, Introduction to Brown Bear Study (higumagaku nyumon), Hokkaido University Press, 2006