Evolution of multiple sperm storage organs in Ommastrephidae

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K05786
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 40030:Aquatic bioproduction science-related
• Research Institution: Tokai University (2019-2020); Shimane University (2018)
• Principal Investigator: Sato Noriyoshi 東海大学, 海洋学部, 特任講師 (40723854)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 精子貯蔵 / スルメイカ / 父子判定 / 乱婚

Outline of Final Research Achievements

Although many cephalopod species including the loliginid squid have no more than two seminal receptacles (SRs), some species of Ommastrephidae have more than twenty SRs on the buccal membrane. In order to investigate how many males were involved in sperm storage within a single SR, we conducted in vitro fertilization assay using spermatozoa collected by squeezing each SR and paternity analysis of resulting embryos. It was found that the females had mated with about 10 males. The sperm storage pattern of each SR varied greatly. This results suggests that this characteristic trait has evolved in order to store sperm from a variety of males, and that securing a diverse sperm resource is important for maintaining abundance.

Free Research Field

行動生態学

Academic Significance and Societal Importance of the Research Achievements

外洋性のアカイカ科に属する種は日本のみならず、世界的にも漁獲量が多く、水産的に重要な分類群である。日本では近年、スルメイカの不漁が続き、資源量の減少が問題となっている。そのため、その資源量の維持メカニズムを理解する事は重要である。本種の産卵生態は研究が進んでいるが、精子貯蔵といった繁殖戦略に関してはほとんど研究が進んでいない。本研究成果はアカイカ科の繁殖において遺伝的多様性の維持が個体の繁殖成功に大きく関わっている事を示すものであり、資源量を考えるうえで重要な貢献を果たしたと言えるだろう。