著者

田中 隼人

出版者

日本動物分類学会

雑誌

タクサ : 日本動物分類学会誌 (ISSN:13422367)

巻号頁・発行日

no.28, pp.17-22, 2010-02-20

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Reproductive isolation and evolution of copulatory organ in eleven interstitial species of the genus Parapolycope (Ostracoda, Myodocopida) were discussed. The shapes of male ejaculatory duct are divided into the three types i.e., a helical tube type (Type H), a curved short tube type (Type S), and tapering long tube type (Type L). And the correlation between the shapes of copulatory organs in both sexes is recognized as, what we call, the "lock and key". After copulation, the female genital openings of Parapolycope sp. 2 are often blocked by a rod-shape structure. The rod-shaped structure is thought as a part of the male copulatory duct. The phylogenetic relationships of several Parapolycope species were estimated by the mitochondrial COT gene sequences. According to this, the extremely long type of copulatory duct must have evolved gradually from the short curved tube type. As a hypothesis to explain the development of the extremely long type of ejaculatory duct, the concept of an "evolutionary arms race" would be applicable.