Distribution of genetic variance in gynogenetic or androgenetic families

Through gynogenetic and androgenetic reproduction, homozygous individuals can be produced in one generation. Selection of homozygous gynogenetic or androgenetic individuals facilitates the production of genetically defined clones. However, to obtain a selection response additive genetic variance is required. The additive genetic variance in homozygous populations doubles as compared to the additive genetic variance in the base population. We examined the possibility of using gynogenesis and androgenesis in estimating additive genetic variance. Therefore, additive genetic relations and the distribution of additive genetic variance between and within homozygous gynogenetic and androgenetic families were derived. Within gynogenetic families variance equals V-A+V-E and between-family variation equals V-A. This theory is used to analyze experimental data on gonad development and fertility in homozygous gynogenetic common carp, Cyprinus carpio. Five gynogenetic families were produced from full sib, outbred female parents. Regular sampling for maturation stage between the age of 13 and 25 months revealed large between-and within-family variance for the gonado somatic index (GSI) and egg quality parameters. Heritabilities were estimated using Gibbs sampling. For the traits GSI at 13 months and the percentage of normal larvae, obtained after fertilization of egg samples at 19 months, heritability estimates were 0.71 and 0.72, respectively. This suggests that these traits are influenced by additive genetic effects; and that homozygous individuals can be successfully selected from our carp families to produce early or late maturing homozygous gynogenetic inbred strains with high egg quality. (C) 1997 Elsevier Science B.V.