Relationships of vertebral deformity with genetic variation and heterosis in the guppy Poecilia reticulata

The present study examined relationships of vertebral deformity with genetic variation and heterosis in the guppy Poecilia reticulata. Vertebral deformed rate varied from 7.3% to 30.6% in nine guppy strains, and negatively correlated with mean heterozygosity at microsatellite and allozyme loci. The regression line indicated that vertebral deformity increases at a rate of 12.2% per 10% decrease of heterozygosity. Since the significant correlation was observed among the genetically differentiated strains, overall heterozygosity may be important for vertebral normality. In a cross between strains, the F1 hybrids showed significantly higher vertebral normality than mid-parent value, indicating heterosis on vertebral normality. Only one of three vertebral deformed types was revealed to show correlation with heterozygosity and heterosis. These results indicate that vertebral deformity is strongly affected by heterozygosity and heterosis in the guppy and the sensitivity differ among the deformed types.