Study on habitat isolation and interspecific interactions of two congeneric shrub species occurring in the Ryukyu Islands

2022 Fiscal Year Final Research Report

• Project/Area Number: 18K14782
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 45030:Biodiversity and systematics-related
• Research Institution: Okinawa National College of Technology
• Principal Investigator: WATANABE KENTA 沖縄工業高等専門学校, 技術支援室, 技術専門職員 (50510111)
• Project Period (FY): 2018-04-01 – 2023-03-31
• Keywords: 種間相互作用 / 棲み分け / 繁殖干渉 / 雑種 / 琉球列島 / ボチョウジ属 / 雌雄異花同株 / 土壌適応

Outline of Final Research Achievements

There are two distinct types of forests are known from the Ryukyu Islands. These forests are corresponding to the soil types, namely limestone and non-limestone forests. Psychotria asiatica is usually growing in the non-limestone forest and P. manillensis is usually growing in the limestone forest; both species are essential species for each forest. These two species are phylogenetically closely related. Therefore, it is very interesting why these two species live in the different forest because this could be the key for the establishment of these two different forests in the Ryukyu Islands. Our results show that these two species have different levels of adaptation to the soil types, but also that intraspecific interactions plays a very important role for the current distribution patterns.

Free Research Field

進化生態学

Academic Significance and Societal Importance of the Research Achievements

本研究では、琉球列島の2タイプの常緑広葉樹林に異所的に生育するアカネ科の近縁種ボチョウジ属ボチョウジとナガミボチョウジの棲み分けが、異なる土壌への適応と、近縁である両種の種間相互作用、並びに分布拡大の歴史的過程により引き起こされているということが明らかになってきた。このことにより、琉球列島の石灰岩林と非石灰岩林という異なる山地森林の成立過程の一端を明らかになった。また琉球列島に限らず、地球上の他の多くの森林においても同様の現象が生じていることは、蓋然性が高く、本研究は植物の分布と森林形成の過程についての理解に大きな進展をもたらすと期待される。