Genetic analysis of testis development in all-male F1 hybrid strains of common carp, Cyprinus carpio

Abstract

Genetics of testis development was examined in 12 all-male F1 hybrid strains of common carp, Cyprinus carpio, produced after crossing four homozygous androgenetic males with three homozygous gynogenetic females. These parents were selected for fast or slow gonad development. In the F1 hybrids, variance components for general and specific combining abilities were examined by regular sampling between 100 and 240 days of age. The variation between F1 crosses for the onset of spermatogenesis (ranging from 100–130 days after hatching) was mainly due to general combining ability and thus additive genetic differences between the inbred parent lines. Testis somatic index (TSI) ranged from 2.0–5.5% at the end of the experiment. Early onset of spermatogenesis coincided with high TSI and late onset of spermatogenesis with low TSI. In the experiment, the female parent affected TSI to a greater extent than the male parent. For this parameter, general combining ability also accounted for most of the variance observed. These data fit to a great extent with the established genetic model for gonadal development in the platyfish, Xiphophorus maculatus.