広橋　教貴　Noritaka Hirohashi PhD

海洋生物学,  動物繁殖学, 性選択 marine biology, animal reproduction, sexual selection

「生殖を巡る雄同士や雌雄の駆け引きが如何に進化を促すか？」Untangling the intersexual and intrasexual tug-of-wars that drive sexual trait evolution.

動物の多くは乱婚です。モラルが低いからで無く、それが雄にとっても雌にとっても有益だからと考えられています。有益性の最たるものが、遺伝的な多様性創出です。これは、将来予期せぬ環境の変化が起きても、子供達が生き残るチャンスが広がるからです。良い品種でも均一な遺伝子セットしか持たない作物は、一旦、害虫が流行ると、全滅してしまうことがあるのと同じです。雌が乱婚だと時に雄どうしの雌を巡る争いが激化します。この競争を避けようと一部の雄は別の進化を遂げ、「ずる賢さ」を身につけることがあります。私の研究室では、この「ずる賢さ」に着目して、主にイカ類を使って研究しています。

Promiscuity is prevalent through animal taxa. But why? Is this because animals have lack of morals? The evolutionary biologists have different idea and seek benefits of being promiscuous for both sexes, particularly for females. Empirical evidence supports that there are direct (e.g., gifts and care from males) and indirect (e.g., genetic diversity) benefits on females. Nevertheless, female promiscuity (or polyandry) had been overlooked for decades before coming to realize that it offers a strong evolutionary force, and currently, we know it as a prior condition whereby postcopulatory sexual selection can occur.  Hence, females favor having mate with multiple males. However, males disfavor having their partners mate with other males, causing a conflict between male and female (sexual conflict). We know very little about a battle of sex in animals except for humans, which let us to study squids exhibiting so many wonderful and mysterious  biological phenomena.  Why not joining us?     

●無脊椎動物で最大サイズのダイオウイカはどのように繁殖するか？The giant squid, a largest species in invertebrates- how do they mate?  

https://www.life.shimane-u.ac.jp/docs/2021071300019/

https://www.livescience.com/giant-squid-monogamous-sperm.html

●ホタルイカは単婚か？ The mystery of the firefly squid- are they monogamous? 

https://www.biorxiv.org/content/10.1101/2019.12.13.875062v1.abstract

https://webun.jp/item/7458601

●ヤリイカの小さなオスは大きな精子を作る。The bigger the better? why small males make big sperm?

http://www.documentary-ch.com/news/20110816.html