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Ploidy and sexual status of the "Carassius auratus" complex in the waters of the Czech Republic
Lusková, Věra ; Lusk, Stanislav ; Halačka, Karel ; Vetešník, Lukáš ; Papoušek, Ivo
The "Carassius auratus" complex, non-indigenous in the Czech Republic, comprises several forms: C. a. auratus (decorative form), C. a. gibelio (predominant), and C. a. langsdorfii (Japanese form). C. a. gibelio is considered a "non-indigenous invasive species". Around 1975, the form invaded the waters of the Czech Republic from the Danube drainage area. The first invasive individuals were triploid females reproducing gynogenetically. The first males occurred in the Dyje River drainage area after 1990 and began transforming to a mixed type, both the sexual and ploidy status of C. a. gibelio populations changing. At present, the overall percentage representation of males in C. a. gibelio populations varies around 30 %, most of them being diploids, triploids occurring only occasionally. A larger part (60 %) of the females, which still predominate in the population, are triploids, the rest being diploids. Tetraploid individuals of both sexes occur quite singly.
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