The maternal origins of the triploid ginbuna (Carassius auratus langsdorfi): phylogenetic relationships within the C-auratus taxa by partial mitochondrial D-loop sequencing

The hyper-variable segments (323 similar to 327 bp) of the mitochondrial D- loop for 169 Carassius auratus fishes in Japan were amplified by the polyme rase chain reaction and the amplified products mere sequenced directly and compared. A dendrogram showing three major clusters was generated with the sequence data for 37 haplotypes at 66 polymorphic sites. One cluster (clust er I) exclusively consisted of the gengorobuna, which was regarded as an in dependent (sub) species. The triploid ginbuna belonged to two remaining clu sters, mainly in the diploid ginbuna cluster (cluster III) and partially in the goldfish cluster (cluster II). This finding suggests that the triploid ginbuna has been derived from two different maternal lineages. The triploi d ginbuna was considered to have come into existence during the last ice ag e on the basis of this phylogenetic data. No geographic differentiation was observed with respect to the triploid ginbuna sampled at three different l ocalities in Japan; the Shibuta River in Kanagawa, Lake Imba in Chiba and L ake Biwa in Shiga. The phylogenetic tree also demonstrated a monophyletic r elationship amongst the nigorobuna, the nagabuna and the ginbuna, sharing c luster III. The nigorobuna and nagabuna populations have most likely arisen from geographic and temporal variations within the ginbuna populations. We also discuss the evolutionary origin of the triploid in view of its patern al ancestors.