Exploring the evolutionary background by raring planktonic larvae of heteronemerteans that become extremely long

• Project/Area Number: 17K07520
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Biodiversity/Systematics
• Research Institution: Hokkaido University
• Principal Investigator: Kajihara Hiroshi 北海道大学, 理学研究院, 准教授 (30360895)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Project Status: Completed (Fiscal Year 2019)
• Budget Amount: ¥5,070,000 (Direct Cost: ¥3,900,000、Indirect Cost: ¥1,170,000); Fiscal Year 2019: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000); Fiscal Year 2018: ¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000); Fiscal Year 2017: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
• Keywords: 紐形動物 / 生活史形質 / 分類 / 系統 / 進化 / 体サイズ / 浮遊幼生 / 海産無脊椎動物

Outline of Final Research Achievements

Positive relation between body size and the number of eggs per an ovary was detected among heteronemerteans. Comparisons of body lengths between three major nemertean subgroups (Palaeo-, Hetero-, and Hoplonemertea) suggested that the difference in body plan is not likely related to body length, as Hetero- and Palaeonemertea did not differ significantly, although Hoplonemertea differed significantly between Hetero- and Palaeonemertea.

Academic Significance and Societal Importance of the Research Achievements

体サイズ規定要因の探求は生物学上興味深い課題の一つであり、多くの研究者が関心を寄せてきた。海産生物における浮遊幼生期や生活史形質の比較研究はこれまでおもに魚類で行われており、無脊椎動物の研究例は少ない。本研究成果は紐形動物における生活史形質の進化的研究における先鞭をつけたという意味で学術的意義が大きく、海洋幼生生態学と進化生態学を結ぶ未開拓の領域へと発展することが期待される。

Research Products

• [Journal Article] New record of the monostiliferous hoplonemertean Gurjanovella littoralis Uschakov, 1926 from Japan (Nemertea, Hoplonemertea, Monostilifera) (2020)
  • Author(s): Hookabe,N., Kajihara, H.
  • Journal Title: Check List Volume: 16 Issue: 2 Pages: 265-269
  • DOI: 10.15560/16.2.265
  • Peer Reviewed / Open Access
• [Journal Article] Occurrence of the freshwater heteronemertean Apatronemertes albimaculosa (Nemertea: Pilidiophora) in Taiwan (2020)
  • Author(s): Kajihara H, Kato A, Nakano T, Lai Y-T.
  • Journal Title: Taiwania Volume: 65 Pages: 81-85
  • NAID: 120006779784
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Record of the heteronemertean Cerebratulus signatus (Nemertea: Pilidiophora: Lineidae) from off Rishiri Island, Hokkaido (2020)
  • Author(s): Kajihara H, Tomioka S.
  • Journal Title: Rishiri Studies Volume: 39 Pages: 19-21
  • Open Access
• [Journal Article] Molecular systematics of the heteronemertean genus Dushia (Nemertea, Pilidiophora), with descriptions of D. wijnhoffae sp. nov. and D. nigra species complex comb. nov. (2019)
  • Author(s): Hookabe N, Schwartz ML, Kajihara H, Norenburg JL.
  • Journal Title: Zootaxa Volume: 4691 Issue: 4 Pages: 333-358
  • DOI: 10.11646/zootaxa.4691.4.2
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] A Population Without Female: Males of Baseodiscus delineatus (Nemertea: Heteronemertea) Reproduce Asexually by Fragmentation. (2019)
  • Author(s): Ikenaga, J., Hookabe, N., Kohtsuka, H., Yoshida, M., and Kajihara, H.
  • Journal Title: Zoological Science Volume: 36 Issue: 4 Pages: 348-353
  • DOI: 10.2108/zs180203
  • NAID: 210000186773
  • Peer Reviewed
• [Journal Article] Morphological and molecular study on Yininemertes pratensis (Nemertea, Pilidiophora, Heteronemertea) from the Han River Estuary, South Korea, and its phylogenetic position within the family Lineidae (2019)
  • Author(s): Park T, Lee S-H, Sun S-C, Kajihara H.
  • Journal Title: ZooKeys Volume: 852 Pages: 31-51
  • DOI: 10.3897/zookeys.852.32602
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Anterior Regeneration in Baseodiscus Hemprichii (Nemertea: Heteronemertea) (2019)
  • Author(s): KAJIHARA, H., and N. HOOKABE.
  • Journal Title: Tropical Natural History Volume: 19 Pages: 39-42
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Presentation] 三崎産イソヒモムシ個体群にはオスしかいない？ （紐形動物門異紐虫類） (2018)
  • Author(s): 池永潤平, 波々伯部夏美, 幸塚久典, 吉田 学, 柁原 宏
  • Organizer: 日本動物分類学会
• [Presentation] Why do certain species of heteronemerteans get so long? (2018)
  • Author(s): Kajihara, H. and Hookabe, N.
  • Organizer: 第9回紐形動物学国際会議
  • Int'l Joint Research