Evolution of the nuchal glands in snakes: origin, diversification, and secondary loss

2016 Fiscal Year Final Research Report

• Project/Area Number: 26440213
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Biodiversity/Systematics
• Research Institution: Kyoto University
• Principal Investigator: Mori Akira 京都大学, 理学研究科, 准教授 (80271005)
• Co-Investigator(Renkei-kenkyūsha): Hirohiko Takeuchi 京都大学, 大学院理学研究科, ポスドク (40726444)
• Research Collaborator: Mori Naoki 京都大学, 大学院農学研究科, 教授 ; Savitzky Alan H. ユタ州立大学, 教授 ; Tang Yezhong 成都生物研究所, 教授 ; Li Ding 成都生物研究所, 准教授 ; Tsai Tein-shun 台湾国立ピントン科技大学, 助手 ; Nguyen Tao Thien ベトナム国立自然博物館, 研究員 ; Das Indraneil マレーシア大学ボルネオ校, 教授 ; Silva Anslem de ペラデニア大学, 客員講師 ; Mahaulpatha Dharshani スリジャヤワルダナプラ大学, 上級講師 ; Jono Teppei 成都生物研究所, ポスドク研究員
• Project Period (FY): 2014-04-01 – 2017-03-31
• Keywords: 進化 / 行動学 / 爬虫類学 / 防御行動 / 化学防衛

Outline of Final Research Achievements

Rhabdophis tigrinus has peculiar defensive organs, called nuchal glands. This snake eats toads, which have toxic skin secretions, and sequesters the toxins to store in its glands. This species also shows peculiar defensive displays that enhance the effectiveness of the toxins for predator avoidance.
We confirmed the presence of similar organs in a total of 18 species of natricine snakes, which show diversified morphological features in the organs. Based on the molecular phylogenetic analysis, we inferred that the nuchal gland system has evolved only once in the ancestor of these species. A line of evidence we obtained suggests that some of those species, which mainly feed on earthworms, have changed the dietary source of nuchal gland toxins from toads to fireflies.

Free Research Field

生物学