GENETIC-ANALYSIS OF TESTIS DEVELOPMENT IN ALL-MALE F1-HYBRID STRAINS OF COMMON CARP, CYPRINUS-CARPIO

Genetics of testis development was examined in 12 all-male F1 hybrid s trains of common carp, Cyprinus carpio, produced after crossing four h omozygous androgenetic males with three homozygous gynogenetic females , These parents were selected for fast or slow gonad development. In t he F1 hybrids, variance components for general and specific combining abilities were examined by regular sampling between 100 and 240 days o f age. The variation between F1 crosses for the onset of spermatogenes is (ranging from 100-130 days after hatching) was mainly due to genera l combining ability and thus additive genetic differences between the inbred parent lines. Testis somatic index (TSI) ranged from 2.0-5.5% a t the end of the experiment. Early onset of spermatogenesis coincided with high TSI and late onset of spermatogenesis with low TSI. In the e xperiment, the female parent affected TSI to a greater extent than the male parent. For this parameter, general combining ability also accou nted for most of the variance observed. These data fit to a great exte nt with the established genetic model for gonadal development in the p latyfish, Xiphophorus maculatus. (C) 1997 Published by Elsevier Scienc e B.V.