Investigating origin and evolution of unique mitochondrial genome found in sea slugs

Research Project

Project/Area Number	16K14787
Research Category	Grant-in-Aid for Challenging Exploratory Research
Allocation Type	Multi-year Fund
Research Field	Evolutionary biology
Research Institution	University of the Ryukyus
Principal Investigator	Yorifuji Makiko 琉球大学, 熱帯生物圏研究センター, ポスドク研究員 (10646467)
Project Period (FY)	2016-04-01 – 2020-03-31
Project Status	Completed (Fiscal Year 2019)
Budget Amount *help	¥3,770,000 (Direct Cost: ¥2,900,000、Indirect Cost: ¥870,000) Fiscal Year 2018: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000) Fiscal Year 2017: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000) Fiscal Year 2016: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Keywords	ミトコンドリアゲノム / ウミウシ / 加速進化 / 集団遺伝 / 遺伝暗号 / ヘテロプラスミー / 浸透性交雑
Outline of Final Research Achievements	Some species of nudibranch mollusks, commonly known as sea slugs, show different phylogenetic relationships when they analyzed by nuclear genomes or by mitochondrial genomes. Here we use the aeolid nudibranch genus Pteraeolidia, which showed such diversity within the genus, and tried to obtain basic information to further investigate their unique evolutionary history. We had to aware that their unique mitochondrial genome was derived from pseudogene; thus, their gene expression and localization in cytoplasm (not in nuclear) were confirmed. We also considered genes and algorithm to use in phylogenetic analyses. So far, we concluded that highly diverged mitochondrial linages were derived from accelerated evolution occurred in mitochondrial protein genes, and this acceleration occurred in higher taxon, not in lower taxon of family or genus.
Academic Significance and Societal Importance of the Research Achievements	軟体動物のうち巻貝類の内部の系統進化関係は未解明で、その分類体系は長く混乱している。特にウミウシ類の属する異鰓亜綱はその筆頭にあり、近年この分類群の分子系統学的解析が進められているが、全ての分類群を網羅した解析例は未だにない。一般向け図鑑の需要が高まる中、確たる情報が一般還元されていない状況である。本申請研究は、異鰓亜綱のうち特にウミウシ類におけるミトゲノムの進化に関する知見をもたらし、異鰓亜綱の系統進化関係解明の糸口となることが期待される。