Secondary contact and introgressive hybridization of two genetical strains of the Ryukyu Scope Owl in relation to environmental modification

2018 Fiscal Year Final Research Report

• Project/Area Number: 16H04737
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Conservation of biological resources
• Research Institution: Hokkaido University
• Principal Investigator: Takagi Masaoki 北海道大学, 理学研究院, 教授 (70311917)
• Co-Investigator(Kenkyū-buntansha): 齋藤 武馬 公益財団法人山階鳥類研究所, 自然誌研究室, 研究員 (40521761)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: リュウキュウコノハズク / 種分化 / 分布域変化 / 異所性 / 同所性 / 交雑 / 進化的に重要な単位 / 亜種

Outline of Final Research Achievements

We detected that hoots of Ryukyu Scops Owls differed between northern (Northern strain) and southern islands (southern strain), which are divided by the Kerama Gap. Genetical analyses revealed that the two strains had 1.5 million divergence history. Individuals in northern strain were significantly smaller than in southern strain. Both strains were evolutionary significant unit (ESU) in each other. Individuals in Northern strain mainly occupied Okinawa Island, but those in Southern strain are occurred sympatrically. Pairing between different strains are occurred frequently, and the hybrid offspring have external morphological and hoots characteristics intermediate between those of Northern and Southern strains. It was inferred that genetic introgression had already been advanced between two strains.

Free Research Field

保全生態学

Academic Significance and Societal Importance of the Research Achievements

二系統は種レベルの遺伝的差異を蓄積していることから、ケラマ海裂による分断種分化した状態にあると結論できる。現時点での沖縄島における二系統の同所的生息は、人為的環境改変、特に森林伐採が南系統の沖縄島へ侵入を可能にした結果である。この二次的同所化は、人為的環境が地史的時間経過による進化の産物であるESUを壊す可能性について考える契機を与えた。さらに今後他種で二次的同所化が生じた際の集められるべきデータのあり方を示す。