Evolutionary game in the social amoeba: Quantification of evolutionary dynamics among interacting diverse cell lineages

2019 Fiscal Year Final Research Report

• Project/Area Number: 16K14805
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Ecology/Environment
• Research Institution: The University of Tokyo
• Principal Investigator: SHIMADA Masakazu 東京大学, 大学院総合文化研究科, 名誉教授 (40178950)
• Project Period (FY): 2016-04-01 – 2020-03-31
• Keywords: 細胞性粘菌 / 協力行動 / 進化動態 / 細胞系譜 / 社会分業 / 社会形成 / 裏切り行動 / 進化ゲーム

Outline of Final Research Achievements

We investigate maintenance of cooperation using a social amoeba Dictyostelium descoideum. We focused on social loss under environments where fitness as a solitary individual surpasses that as a social group member. From live-cell imaging, we revealed that cells that switch back to the solitary state were disadvantageous, because they were forced to take an altruistic role when allowed to interact with social cells. The results indicate that division of labor process of the social amoeba will contribute to maintaining cooperation even under environments where solitary cells are advantageous. Furthermore, to measure evolutionary dynamics under the prevention of social loss, populations with random mutations were constructed, and nucleotide sequences of the mutants were decided with next-generation sequencer. We are in the trial and error stage to find an effective way to measure each mutant number, and have some good prospect on quantitative measurement of the evolutionary dynamics.

Free Research Field

進化生態学

Academic Significance and Societal Importance of the Research Achievements

生物が複雑な社会性を進化させるためには、安定して協力を継続する必要がある。しかし協力の継続は、いくつかの要因で阻害されうる。一つは協力を搾取する裏切り行動の侵入である。もう一つは環境変動で協力よりも単独行動が有利となれば協力はあっさり失われるだろう。これまで前者に対しては、多くの解決策が見出されてきた。しかし後者は説明が難しく国内外でも研究例が少ない。本研究は、細胞性粘菌が既に持っている社会分業体制が、副産物として単独行動が有利な環境でも協力を維持するのに役立つことを世界に先駆けて示している。さらにこの独自の実験系を用い、進化動態を実測する手法を開発途上にあり、今後さらなる発展が見込まれる。