Incongruence between cpDNA- and nrDNA-based phylogenies suggests the allopoliploid origin of tetraploid Hydrangea liukiuensis (Saxifragaceae), an endemic shrub distributed on Okinawajima Island in the central Ryukyus.

琉球大学21世紀COEプログラム「サンゴ礁島嶼系の生物多様性の総合解析」平成19年度成果発表会（平成20年3月1日開催）　招待講演会会場：理系複号棟102号室，ポスター発表会場：琉球大学50周年記念館1

Studies on polyploid speciation in vascular plants and its evolutionary meanings on subtropical islands.

2007年度～2009年度科学研究費補助金（基盤研究(Ｃ)）研究成果報告書研究概要（和文）：琉球列島に分布するニガナ属（キク科）、スイカズラ属（スイカズラ科）、アジサイ属（ユキノシタ科）などを対象に、雑種の形成や倍数化を伴う種分化の過程を形態、染色体、分子情報などを用いて解析した。本研究の結果、雑種が分布を拡大して親種を駆逐しているケースなどが確認され、閉鎖的な島嶼環境下における多様性の形成に、雑種形成や倍数化が重要な役割を果たしていることを明らかにした。研究概要（英文） : Hybrid and polyploid speciation within the Ryukyu Archipelago were analyzed based on morphological, cytological and molecular data. Studies on plant taxa such as the genus Ixeris (Compositae), Lonicera (Caprifoliaceae) and Hydrangea (Saxifragaceae) suggested an importance of such a speciation process to increase plant diversity within the closed insular environment

Karyotype of Ophiopogon reversus (Convallariaceae) from Taiwan and the Southern Ryukyus

Karyotypes of Ophiopogon reversus (Convallariaceae) collected from four localities in Taiwan and one locality on Yonaguni-jima Island in the southern Ryukyus of Japan were reported for the first time. Those of O. jaburan collected from three major islands (Amami-oshima, Tokuno-shima and Okinawa-jima) of the central Ryukyus were also investigated for comparison. All plants of O. reversus and O. jaburan investigated were diploid (2n = 36) based on the basic chromosome number of x = 18. Among 36 chromosomes of O. reversus, one pair of short chromosomes with submedian centromeres had secondary constrictions at the proximal region of the long arms. Based on this character, O. reversus is cytologically distinguishable from O. jaburan, in which one pair of short metacentric chromosomes had secondary constrictions at the proximal region of the short arms