Characteristics of karyotype and morphology in auto-4n, 4n-F1 and reciprocal interploid 3n cross of blunt snout bream Megalobrama amblycephala

摘要

The karyotype and morphology of auto-4n, 4n-F1 and reciprocal interploid 3n cross were compared with that of 2n blunt snout bream Megalobrama amblycephala . The results showed: (1) the chromosome number of tetraploid (including 4n and 4n-F1) and reciprocal interploid 3n offspring were 96 and 72, 2 and 1.5 times as many as that of diploids. Four larger sm1 chromosomes in the karyotype of the tetraploid could be observed distinctively and were used as marker chromosomes. (2) according to the 9 traditional meristic characteristics, 3n or 4n polyploids had significantly lower body length/body height ratio and body length/head length ratio than those of the 2n control. However, significantly higher soft dorsal fin length/body length ratios were found in polyploids. (3) principal component analysis including 29 parameters showed morphological divergence in 4n, 4n-F1, reciprocal 3n, and 2n control; mainly caused by the torso, i.e. body length/body height. It could be considered as morphological marker to distinguish polyploids from diploid. (4) cluster results showed that the positive 3n cross had a closer relationship with the negative 3n hybrid, while reciprocal 3n cross offspring had a closer correlation with 2n control, as compared to auto-tetraploid populations[ A cta Zoologica Sinica 51(3): 455–461, 2005].