2018 Fiscal Year Final Research Report

Researching adaptive radiation to 1600 m-bottom of the Baikal sculpins in subarctic lake by their molecules and life histories

Research Project

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Project/Area Number	15H05235
Research Category	Grant-in-Aid for Scientific Research (B)
Allocation Type	Single-year Grants
Section	海外学術
Research Field	Biodiversity/Systematics
Research Institution	Kochi University
Principal Investigator	Kinoshita Izumi 高知大学, 教育研究部総合科学系黒潮圏科学部門, 教授 (60225000)
Co-Investigator(Kenkyū-buntansha)	田原大輔福井県立大学, 海洋生物資源学部, 准教授 (20295538) 岩田明久京都大学, アジア・アフリカ地域研究研究科, 教授 (20303878) 馬渕浩司国立研究開発法人国立環境研究所, 生物・生態系環境研究センター, 主任研究員 (50401295) 安房田智司大阪市立大学, 大学院理学研究科, 准教授 (60569002) 酒井治己国立研究開発法人水産研究・教育機構, 水産大学校, 教授 (80399659)
Research Collaborator	YOKOYAMA Ryota GOTO Akira SIDELEVA G Valentina
Project Period (FY)	2015-04-01 – 2019-03-31
Keywords	バイカル湖 / カジカ類 / 適応放散 / 種分化 / 古代湖
Outline of Final Research Achievements	We investigated shallower waters (300-500 m d) between southern and central regions in seasons before freezing (September) and after thawing (June). Thermoclines were found to 100 m-depth in June, and it was vertically well-mixed in September. DO was enough to bottoms in both seasons. Many species of deep-sculpins were used as their nurseries over this area in June. Otoliths could be collected from hatched larvae of pelagic sculpin, and daily increment and hatch-check could be recognized. Molecular phylogeny of Asprocottus species was reconstructed based on a ca. 1500bp fragment of m-DNA. No haplotypes from these formed monophyletic groups that corresponded to species boundaries, suggesting introgression through hybridization and/or incomplete lineage sorting due to rapid speciation. Compared sperm traits among three non-copulatory species and one copulatory species, sperm traits may have evolved adaptively in association with the evolution of copulation and viviparity.
Free Research Field	海洋生物学
Academic Significance and Societal Importance of the Research Achievements	耳石日周輪の調査から，バイカルカジカの個体発生の速度は極めて遅いのに対して，mtDNA解析では，種分化の速度は極めて速いことが明らかになった．このことは，生物の個体発生と系統発生は，時間的に不の関係にあり，これまでの生物学の原理を刷新する可能性を秘めている．さらに，バイカルカジカの種分化は，同じ古代湖であるタンガニイカ湖と比べて極めて新しく，過去の温暖化による不凍結期によって，数度リセットされた可能性が示唆され，現在の地球温暖化を再考する場合，重要な参考資料となり得る．多くのカジカ深部種が，央湖盆の比較的浅部を成育場としていた事実は，本湖の環境保護ならびに種保全を考える上で意義深い．