ECOLOGICAL AND EVOLUTIONARY STUDY ON GAMMARIDS IN LAKE BAIKAL

Research Project

Project/Area Number	05640717
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	生態
Research Institution	TEIKYO UNIVERSITY
Principal Investigator	MASHIKO Kazuo TEIKYO UNIVERSITY,DEPARTMNT OF LITERATURE,ASSOCIATE PROFESSOR, 文学部, 助教授 (00082321)
Co-Investigator(Kenkyū-buntansha)	MORINO Hiroshi IBARAKI UNIVERSITY DEPARTMENT OF SCIENCE,ASSOCIATE PROFESSOR, 理学部, 助教授 (30091870)
Project Period (FY)	1993 – 1994
Project Status	Completed (Fiscal Year 1994)
Budget Amount *help	¥2,000,000 (Direct Cost: ¥2,000,000) Fiscal Year 1994: ¥500,000 (Direct Cost: ¥500,000) Fiscal Year 1993: ¥1,500,000 (Direct Cost: ¥1,500,000)
Keywords	Species Diversity / Genetic population structure / Gammarids / Lake Baikal / Phylogeny / Morphological diversity / Allozyme analysis / Freshwater Biology / Evolution / Environmental fluctuation / 形態学 / 陸水生物学
Research Abstract	This research project is undertaken to investigate evolutionary backgrounds of the great diversity of species in Lake Baikal. In a long isolated biotope like Lake Bailal, the number of species found at the present time is regarded to be nearly due to cumulative effects of speciation and extinction in the past. Therefore, "How speciation took place in this geologically stable evironments" is a fundamental question about the species diversity now found there. To this problem, population-genetic approach was made by starch-gel electrophoresis for a few species of gammarids of the genus Eulimnogammarus, especially a littoral species E.cyaneus. Allozyme analysis was undertaken for 21 gene loci coding for 16 enzymes in this study. It was found that local populations of E.cyaneus collected at 26 localities along the shoreline were genetically differentiated into the major two regional groups, northern and southern-basin groups. The southern-basin group was further genetically divided into the two sub-groups, middle west-coast and far southern-coast groups of the outlet of the Angara River. These genetic differentiations seem to have been brought out by environmental genetic barriers operating now or operated in the past. We also made morphological investigations on the genus Eulimnogammarus endemic to this lake. It is generally accepted that Eulimnogammarus sense stricto is closely related to the genus Echinogammarus which is widely distributed in the European continent. Hence, morphological examination about the relationship between these two groups is of great importance in considering the origin of Eulimnogammarus in Lake Baikal. Hence, phyletic analysis was undertaken in them with newly found diagnostic traits, and the degree of morphological diversity in the Baikalian species was examined.