“生態系はどう構造化されているか” 木村正人 教授

研究分野・テーマ・内容

研究分野 生態遺伝学
研究テーマ 共進化および環境適応

研究内容

寄生蜂の寄生を受けると寄主であるショウジョウバエは抵抗性を進化させる可能性がある。そうすると、対抗して寄生蜂は寄生力を高めるかもしれない。そうするとショウジョウバエはさらに抵抗性を高める・・・、というように、互いに影響しあって進化することで、ショウジョウバエは抵抗性を、寄生蜂は寄生力をどんどん強化する可能性がある。こういう現象を軍拡競争と呼ぶ。現在の興味は、どのような状況で軍拡競争が起こるか、その結末はどうなるか、ということにある。また、低温や高温に対する適応についても研究を進めている。

メッセージ

 「共進化」とか「生態系の構造」とか、浮世離れしたことを考えたりしていますが、こんなことを考える人は世の中にそれほど多く必要ではなく、この道で口に糊するのはなかなか難しそうです。

name KIMURA Masahito

Research subject

Specialized field

Ecological and Evolutionary Genetics

Key words

  • ・Parasitoids-Drosophila interactions
  • ・Coevolution
  • ・Arms-race
  • ・Population dynamics

Research subject

Parasitism is one of major life styles of insects, and parasitoids comprise more than 20% of all insect species. Adult parasitoid females lay one or more of their eggs on, in or close to their host, usually immature sage of another insect, and the larva consume the body of the their host, leading to the death of the host. Thus, parasitoids are one of the major regulatory factors affecting host densities and act as major selective force on the host. As a consequence, hosts could evolve resistance mechanisms against parasitoids, which in turn leads to the evolution of parasitism capacity of parasitoids. Such arms-race of parasitoids and hosts is often analysed with theoretical models, but its aspects in nature is still little understood.

We are studying ecological and evolutionary aspects of Drosophila-parasitoids interactions in nature. Drosophila species, particularly D. melanogaster and its relatives, are used as model organisms for the study of genetics, development, physiology and evolution. However, their ecology, particularly their interactions with other organisms, are still poorly understood. One of our goals is to understand how their populations are regulated through their interactions with parasitoids. One more goal is to understand how host resistance and parasitoid virulence have evolved (i.e., how arms-race occurs). For this purpose, Drosophila species are excellent materials, since a large amount of knowledge on their genetics, development and physiology has already been accumulated.