Abstract
The diploid-polyploid complex in the Japanese silver crucian carp (ginbuna), Carassius auratus langsdorfii, includes a diploid bisexual form, a triploid gynogenetic form and a tetraploid gynogenetic form. However, the origin of the polyploids remains to be clarified. Flow cytometric and electrophoretic analyses of Japanese crucian carp demonstrated that all the individuals with a two-banded pattern for an AMY-2 gene were polyploid, and 90% of the polyploids gave such a two-banded pattern. One of the two bands was not found in diploid subspecies in Japan but was present in both Korean crucian carp and goldfish. The diploid subspecies, kinbuna (C.auratus subsp.), which is distributed along the Pacific coast of eastern Japan, generated a diagnostic band of phosphoglucomutase. This band was also found in the polyploid “ginbuna” from the same region, but was observed in neither triploids nor diploids from other regions. The region-specific distribution of patterns of muscle lactic dehydrogenases indicated that the crucian carp examined in the present study could be divided into three groups, which originated, respectively, from the Pacific coast of eastern Japan, the Sea of Japan coast of eastern Japan, and western Japan. These results suggest a possible polyphyletic origin of polyploid forms of “ginbuna” via multiple hybridizations.
