Coexistence of diploid, triploid and tetraploid crucian carp (Carassius auratus) in natural waters

Abstract

BackgroundCrucian carp (abbreviated CC) belongs to the genus of Carassius within the family of Cyprinidae. It has been one of the most important freshwater species for Chinese aquaculture and is especially abundant in the Dongting water system of Hunan province. CC used to be considered as all diploid forms. However, coexistence of diploid (abbreviated 2nCC), triploid (abbreviated 3nCC) and tetraploid crucian carp (abbreviated 4nCC) population of the Dongting water system was first found by our recently researches.ResultsWe examined the ploidy level and compared biological characteristics in different ploidy CC. In reproductive mode, 2nCC was bisexual generative and 4nCC generated all-female offspring by gynogenesis. However, 3nCC generated progenies in two different ways. 3nCC produced bisexual triploid offspring fertilized with 3nCC spermatozoa, while it produced all-female triploid offspring by gynogenesis when its ova were activated by heterogenous spermatozoa. The complete mitochondrial DNA of three different ploidy fishes was sequenced and analyzed, suggesting no significant differences. Interestingly, microchromosomes were found only in 3nCC, which were concluded to be the result of hybridization. Allogenetic DNA fragments of Sox genes were obtained in 3nCC and 4nCC, which were absent in 2nCC. Phylogenetics analysis based on Sox4 gene indicated 3nCC and 4nCC formed a separate group from 2nCC.ConclusionsIn summary, this is the first report of the co-existence of three types of different ploidy crucian carps in natural waters in China. It was proved that the coexistence of different ploidy CC was reproductively maintained. We further hypothesized that 3nCC and 4nCC were allopolyploids that resulted from hybridization. The different ploidy CC population we obtained in this study possesses great significance for the study of polyploidization and the evolution of vertebrates.

DNA barcoding and species and subspecies classification within genus <I>Carassius</I>

“…发育生殖的三倍体和四倍体, 特别是这些雌核发育 多倍体中有一定比例的可育雄性个体 (Fan & Shen 1990;Gui & Zhou，2010;Xiao et al, 2011)。以上特 性使得鲫成为研究脊椎动物性别决定机制和生殖 方式调控机制的良好模型 (Gui & Zhou，2010)。因 此, 鲫属鱼类不仅具有重要的生态和经济价值, 其 生物学特性也日益引起生物学家的关注。 我国鱼类学家认为中国大陆鲫属鱼类可以划 分为鲫 (C. auratus)和黑鲫 (C. carassius)两种, 前 者又可以分为鲫 (C. auratus auratus)指名亚种和银 鲫 (C. auratus gibelio)亚种 (Chen & Huang, 1982;Luo & Yue, 2000)。由于采样的局限性, 我国学者并 未研究日本列岛及其周边的鲫鱼分类。日本学者则 将日本的鲫鱼分为鲫 (C. auratus)与白鲫 (C. cuvieri) 两种, 前者又被分为 5 个亚种：C. auratus subsp.…”

A novel allotetraploid gibel carp strain with maternal body type and growth superiority

“…In the past, tetraploid individuals were reported in Carassius complex, but their chromosome numbers were found to be various, in which several types of different tetraploids with 212, 206, 210, or 200 chromosomes were described respectively (Gui et al, 1993a;Zhao et al, 2004;Zhu and Gui, 2007;Xiao et al, 2011). In comparison with the previously described allotetraploids that manifest some morphological body type of the paternal common carp (Gui et al, 1993a;Zhu and Gui, 2007), the currently established allotetraploid strain has been found to have morphological body type and morphometric traits that are basically identical to the maternal gibel carp.…”

Changes in nutritional parameters in diploid and triploid African catfish Clarias gariepinus following chlorpyrifos exposure

“…Triploidy has been shown to be naturally occurring in several fish species (e.g. Carassius auratus; Murayama et al 1986, Xiao et al 2011. Despite the presence of triploid fish in aquatic environments and their promising application in the aquaculture industry (e.g.…”