The evolution of discontinuity as a result of chromosome evolution

• Project/Area Number: 17KT0028
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Multi-year Fund
• Section: 特設分野
• Research Field: Constructive Systems Biology
• Research Institution: National Institute of Genetics
• Principal Investigator: Kitano Jun 国立遺伝学研究所, ゲノム・進化研究系, 教授 (80346105)
• Project Period (FY): 2017-07-18 – 2020-03-31
• Project Status: Completed (Fiscal Year 2019)
• Budget Amount: ¥18,460,000 (Direct Cost: ¥14,200,000、Indirect Cost: ¥4,260,000); Fiscal Year 2019: ¥6,370,000 (Direct Cost: ¥4,900,000、Indirect Cost: ¥1,470,000); Fiscal Year 2018: ¥6,890,000 (Direct Cost: ¥5,300,000、Indirect Cost: ¥1,590,000); Fiscal Year 2017: ¥5,200,000 (Direct Cost: ¥4,000,000、Indirect Cost: ¥1,200,000)
• Keywords: 種分化 / 多様性 / 染色体 / 適応進化 / 魚類 / ゲノム / 適応 / 魚

Outline of Final Research Achievements

We have determined whole genome sequences of over 20 stickleback populations (about 10 fish per population). The coverage for each individual was about x10. Calculation of gene flow rates showed that gene flow rates between different ecotypes varied among systems, suggesting that we have established a system suitable for studying the speciation continuum. We also found a strong positive correlation between the recombination rates and the gene flow rates, suggesting the importance of recombination suppression for reproductive isolation. We also found that the genomic region responsible for adaptive phenotypic divergence showed higher genetic differentiation than other regions. We also identified several chromosomal structural changes.

Academic Significance and Societal Importance of the Research Achievements

生物に見られる重要な特徴の一つは種分化である。種分化とは一つの共通祖先から、枝分かれによって分化した集団が生じ、生殖隔離によって違いが維持されるに至る連続的な過程である。換言すると、生物が多様化しつつ、均一なものへとマージしてしまわない仕組みの解明が、生命の理解に必須である。研究代表者らはこのような連続的な種分化過程を研究するのに最適な系を確立した。また、種分化を促進する要因として組換え抑制の進化が重要であることを示した。これら組換え抑制の進化に染色体構造変化が関与していそうである。本成果は、種分化を促進する要因に、重要な洞察を与える。

Research Products

• [Journal Article] Genome-wide patterns of divergence and introgression after secondary contact between Pungitius sticklebacks. (2020)
  • Author(s): Yamasaki, Y.Y., Kakioka, R., Takahashi, H., Toyoda, A., Nagano, A. J., Machida, Y., Moller, P.R., and Kitano, J.
  • Journal Title: Philosophical Transactions of the Royal Society B: Biological Sciences Volume: in press
  • Peer Reviewed
• [Journal Article] Differences in the contributions of sex-linkage and androgen regulation to sex-biased gene expression in juvenile and adult sticklebacks. (2020)
  • Author(s): Kitano, J., Kakioka, R., Ishikawa, A., Toyoda, A., and Kusakabe, M.
  • Journal Title: Journal of Evolutionary Biology Volume: in press
  • Peer Reviewed
• [Journal Article] Armor plate diversity in Japanese freshwater threespine sticklebacks (2019)
  • Author(s): Yamasaki, Y.Y., Mori, S., Kokita, T., and Kitano, J.
  • Journal Title: Evolutionary Ecology Research Volume: 20 Pages: 51-67
  • Peer Reviewed
• [Presentation] トゲウオにおける適応放散の遺伝機構 (2019)
  • Author(s): 北野潤
  • Organizer: 日本遺伝学会分科会
  • Invited
• [Presentation] Genomic signatures of introgression at the late stage of stickleback speciation (2017)
  • Author(s): Jun Kitano, Mark Ravinet, Asano Ishikawa, Kohta Yoshida, Ryo Kakioka
  • Organizer: European Society of Evolutionary Biology 2017
  • Int'l Joint Research
• [Presentation] A key role for an omega-3 fatty acid desaturase in stickleback freshwater colonization (2017)
  • Author(s): Jun Kitano, Asano Ishikawa
  • Organizer: Society for Molecular Biology and Evolution 2017
  • Int'l Joint Research