Analysis of the formation mechanisms and biological characteristics in WuLi carp-like fish derived from the hybrid of Cyprinus carpio var. Quanzhounensis (♀) × Carassius auratus red var. (♂)

Distant hybridization is an effective strategy for creating polyploids and developing new germplasm resources in fish genetic breeding. The WuLi carp-like fish (2 n = 100, WCL) had been obtained through distant hybridization between female WuLi carp ( Cyprinus carpio var. Quanzhounensis, 2 n = 100, WLC) and male red crucian carp ( Carassius auratus red var., 2 n = 100, RCC), and extensive and in-depth studies had subsequently been conducted on it. Although some characteristics of the female parent WLC had been retained, significant morphological changes had occurred in the hybrid offspring. Systematic comparative analyses had been conducted on WCL, encompassing morphological traits, DNA content, chromosome number, 5S rDNA sequences, gonadal sections, microsatellite DNA markers, fluorescence in situ hybridization (FISH), and mitochondrial DNA. The results indicated that WCL had exhibited clear maternal inheritance in morphological traits, DNA quantification, chromosome configuration, 5S rDNA sequences, FISH signals, and mitochondrial DNA, with the FISH results being entirely consistent with those of the female parent. Microsatellite analysis had clearly confirmed the integration of DNA fragments from the male parent RCC into the WCL genome. Furthermore, observations of gonadal sections had revealed that both male and female WCL individuals had been fertile, with the number of females exceeding that of males. Based on a comprehensive analysis of the experimental results, WCL was inferred to be a natural gynogenetic offspring derived from hybridization, with its distinct morphological characteristics having possibly resulted from the insertion of paternal genetic material. The acquisition of WCL provides an ideal model for investigating the effects of hybridization on genomic composition in fish.