珠江卷口鱼不同地理种群的形态变异

运用传统生物形态学和框架分析方法,对珠江水系中栖息于柳江、浔江、西江的卷口鱼(Ptychidio jordani Myers)的形态变异进行了分析。根据高背、平背体型分析了体长/体高比例与地理、性别和年龄的相关性。结果显示:体长/体高比例与年龄呈显著负相关,随着年龄增长,卷口鱼逐渐趋向于高背型;三个江段卷口鱼可数性状数据卡方检验没有显著差异;三个江段卷口鱼可量性状数据和框架数据聚类分析、判别分析和主成分分析显示三个江段的卷口鱼形态差异明显,有一定程度的分化;聚类和主成分分析显示柳江群体变异最大,而西江卷口鱼则分化成两个群体,其中一个与浔江群体关系较近。判别分析构建的判别公式可以区分三个江段四个群体的卷口鱼,判别正确率达到99.2%。不同江段卷口鱼的差异表现在整个鱼体上,不能用单独的一或二个参数进行鉴别。

Morphological variation of the ratmouth barbell Ptychidio jordani from different geographic populations in the Pearl River Basin

The ratmouth barbel(Ptychidio jordani Myers) is a cyprinid fish native to the Pearl River basin in southern China.In this paper,morphological variation and population biology of the ratmouth barbell were studied using traditional morphological and truss network analysis.A total of 118 individuals was sampled from three sites(Liuzhou,Guiping and Yunan) in the Pearl River basin with the help of local fishermen.The two kinds of body shapes were noted when sampling,the "high back" shape and the "calm back" shape.Relationships between body shape,habitation,sex and age were analyzed.The results showed a significant negative relationship between age and ratios of body length and body depth.Body depth generally increased with age.Thirty nine sets of morphological data were collected.Seven sets of meristic character data from 3 sites did not differ significantly as judged by chi-square analysis.Thirty two sets of measurable character data with truss network data were used for multivariate analysis,such as cluster analysis, discriminant analysis and principal component analysis.These indicated that the morphological variation among the fish from 3 Pearl River basin sites was significant.Cluster analysis showed that the Liujiang-population was specially separated from the other populations.The results of cluster analysis showed that the Xijiang population was separated into two groups,one of which was similar to the Xunjiang-population.We separated all individuals into four groups for analysis.The four populations of the fish in 3 sites could be distinguished by using the 4 formulae established with discriminant analysis.Discrimination accuracy reached 99.2%.Principal component analysis also distinguished the four populations.Differences between fish from the 3 sites involved the entire body and they could not be identified using only one or two parameters.