Variations in the Mitochondrial Genome of a Goldfish-Like Hybrid [Koi Carp ( ♀) × Blunt Snout Bream (♂)] Indicate Paternal Leakage

Previously, a homodiploid goldfish-like fish (2n = 100; GF-L) was spontaneously generated by self-crossing a homodiploid red crucian carp-like fish (2n = 100; RCC-L), which was in turn produced via the distant hybridization of female koi carp (Cyprinus carpio haematopterus, KOC, 2n = 100) and male blunt snout bream (Megalobrama amblycephala, BSB, 2n = 48). The phenotypes and genotypes of RCC-L and GF-L differed from those of the parental species but were similar to diploid red crucian carp (2n = 100; RCC) and goldfish (2n = 100; GF), respectively. We sequenced the complete mitochondrial DNAs (mtDNAs) of the KOC, BSB, RCC-L, GF-L, and subsequent generations produced by self-crossing [the self-mating offspring of RCC-L (RCC-L-F2) to the self-mating offspring of RCC-L-F2 (RCC-L-F3) and the self-mating offspring of GF-L (GF-L-F2)]. Paternal mtDNA fragments were stably embedded in the mtDNAs of both lineages, forming chimeric DNA fragments. In addition to these chimeras, several nucleotide positions in the RCC-L and GF-L lineages differed from the parental bases, and were instead identical with RCC and GF, respectively. Moreover, RCC-L and GF-L mtDNA organization and nucleotide composition were more similar to those of RCC and GF, respectively, compared to parental mtDNA. Finally, phylogenetic analyses indicated that RCC-L and GF-L clustered with RCC and GF, not with the parental species. The molecular dating time shows that the divergence time of KOC and GF was about 21.26 Mya [9...

Source: Frontiers in Genetics - January 21, 2021 Category: Genetics & Stem Cells Source Type: research