团头鲂人工同源四倍体、自繁后代、倍间交配后代的染色体组型及形态遗传特征

以2n团头鲂为对照,对诱导产生的同源四倍体、自繁后代(4n-F1)和倍间交配后代(正交3n和反交3n)的染色体组型及形态遗传特征进行比较分析。结果发现:(1)团头鲂四倍体(包括4n和4n-F1)和正反倍间交配三倍体的染色体众数分别为96和72,是2n团头鲂的2倍和1·5倍;在四倍体团头鲂组型排列中,sm1的四条较大的染色体明显可见,可视为标记染色体;(2)9个比例性状的测量结果显示,多倍体的体长/体高、体长/头长比例值显著小于2n团头鲂(P<0·05);而对于背棘长/体长比例值,多倍体则显著大于2n团头鲂(P<0·05);(3)29个参数的主成分分析结果表明,团头鲂同源4n、4n-F1、倍间交配3n及2n团头鲂等5个不同倍性群体的传统形态差别很大部分是由躯干部的形态差异,主要是体长/体高引起的,可作为团头鲂多倍体与二倍体群体鉴别的形态依据;(4)聚类结果显示,正交3n和反交3n相聚类,亲缘关系最近,然后,它们与4n-F1聚类后,再与4n奠基群体聚类,与二倍体群体的聚类关系较远动物学报51(3):455-461,2005]。

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

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.