2026-06-04 北海道大学,山階鳥類研究所
◆リュウキュウコノハズクは、沖縄島と宮古島の間に位置するケラマ海峡によって分断された北系統と南系統の二つの遺伝的系統群を形成している。本研究では奄美大島から与那国島までの個体群の羽色を定量解析した結果、北系統と南系統で羽色が有意に異なることが判明した。一方、両系統が共存する沖縄島では羽色差が見られず、系統間で交雑が進行している可能性が示唆された。また、徳之島や西表島では独自の羽色変異が認められた。気温や植生などの環境要因と羽色との明確な関連は確認されず、羽色の違いは環境適応よりも島嶼間の地理的隔離と遺伝的分化によって形成された可能性が高いと考えられる。
◆本研究は、島嶼環境における生物多様性形成や種内分化の進化過程を理解するうえで重要な知見を提供する。
リュウキュウコノハズクどちらも成鳥だが、同じ種でも羽色の差異が大きい
＜関連情報＞
- https://www.hokudai.ac.jp/news/2026/06/post-2309.html
- https://www.jstage.jst.go.jp/article/osj/advpub/0/advpub_OSJ-2025-017/_article/-char/ja
琉球列島におけるリュウキュウコノハズクの北系統個体群と南系統個体群の羽色の差異 Differences in plumage coloration between northern and southern populations of the Ryukyu Scops Owl in the Ryukyu Archipelago
Hinako HANZAWA, Takema SAITOH, Akira SAWADA, Masaoki TAKAGI
Ornithological Science Published:2026/06/04
DOI:https://doi.org/10.2326/osj.OSJ-2025-017
抄録
Avian plumage coloration is a crucial research topic in evolutionary ecology and can be associated with genetic clade and the unique evolutionary processes on geographically isolated islands. This study investigated plumage coloration in Ryukyu Scops Owl Otus elegans among islands and genetic clades. We also examined whether differences in plumage were associated with clade, island, and environmental factors (latitude, temperature, precipitation, and vegetation). In this study, plumage coloration was quantified from photographs of owls captured on eight islands, and genetic clades were determined using COI gene analysis. The results showed that individuals of the northern clade had significantly darker plumage than individuals of the southern clade. However, this difference was not observed on Okinawa Island, where both clades are present, suggesting that hybridization occurs there. Differences in plumage coloration were also observed among some of the islands. In contrast, no significant correlation was found between environmental factors such as latitude, temperature, annual precipitation, and vegetation, and plumage coloration. In conclusion, this study suggests that variation in Ryukyu Scops Owl plumage is shaped primarily by genetic divergence resulting from vicariance and island-specific factors, rather than continuous environmental clines across its range. This study suggests that geographic isolation plays a significant role in the evolution of morphological traits in organisms.
