Ichthyological Research

, Volume 43, Issue 2, pp 117-124

First online:

Genetic markers distinguishing between the two subspecies of the rosy bitterling,Rhodeus ocellatus (Cyprinidae)

  • Yoshikazu NagataAffiliated withDepartment of Biology, Osaka Kyoiku University
  • , Tadashi TetsukawaAffiliated withDepartment of Biology, Faculty of Engineering, Kansai University
  • , Takanori KobayashiAffiliated withFish Genetics Division, National Research Institute of Aquaculture
  • , Ken-ichi NumachiAffiliated withDepartment of Fisheries, Faculty of Marine Science and Technology, Tokai University

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Eleven populations of the rosy bitterling,Rhodeus ocellatus, from different localities in Japan, were genetically compared at 16 protein-coding loci using starch-gel electrophoresis. Two loci,Ldh-2 andPgdh, were demonstrated as diagnostic markers for the identification of two subspecies;R. ocellatus kurumeus, which is native to Japan, andR. ocellatus ocellatus, which was introduced from China. The two subspecies were distinguished by the complete substitution of different alleles between them. Population ofR. ocellatus kurumeus occurring in Yao City, Osaka, and in Kanzaki, Saga Prefecture were genetically closely related to each other (genetic distance: D=0.056) but distantly so toR. ocellatus ocellatus from Saitama Prefecture (D=0.202 or 0.265). Electrophoretic analyses also elucidated the existence of hybrid populations of the two subspecies. The populations ofR. ocellatus kurumeus in Yao City had lower genetic variability and a lower incidence of white coloration on the ventral fins than populations of the same in Saga Prefecture. The present study strongly implies that the introduction of the foreign freshwater fishes with subspecific differentiation, into the original range of indigenous subspecies, should be averted not to bring the genetic pollution.

Key words

Rhodeus ocellatus isozyme hybridization inbreeding effects genetic introgression