广西主要养殖区内逃逸尼罗罗非鱼形态差异分析

【目的】明确地理生境对野外逃逸尼罗罗非鱼形态变异的影响,为今后研究罗非鱼种群入侵及制定防治对策提供参考依据。【方法】在广西玉林、南宁、钦州、贵港、防城港和北海6个主要养殖区域采集一龄左右的雄性逃逸尼罗罗非鱼自然群体,以形态测量、主成分分析、判别分析和聚类分析等方法进行形态特征和多变量形态度量分析。【结果】在尼罗罗非鱼全长、体长、体高、头长、吻长和体质量方面,均以玉林地区的最高、钦州地区的最低,且两地差异显著(P0.05)。主成分分析结果显示,前3个主成分贡献率分别为74.31%、9.23%和6.21%,累积贡献率达89.75%,能较好地概括不同养殖区域野外逃逸尼罗罗非鱼的生长特征。判别分析结果表明,通过全长、体厚、头长、吻长、眼径、眼间距和体质量等7项体表性状建立的判别函数能有效区分不同养殖区域的尼罗罗非鱼,其综合判别准确率为96.11%。经聚类分析发现,钦州地区的尼罗罗非鱼与其他地区的相似性最低,变异程度最大,单独聚为一支。不同养殖区域尼罗罗非鱼样本体质量与全长、体长、体高、体厚、头长、吻长、眼径、眼间距间的相关性均极显著(P0.01),其中与全长、体长和体高的相关系数较高,分别为0.9375、0.9359和0.8327,而与眼径的相关性最低(0.5947)。【结论】主成分分析和判别分析是辨别逃逸罗非鱼来源的可行手段,而分析逃逸尼罗罗非鱼的全长、体长和体质量有助于了解其生存状态,并为控制其入侵提供参考依据。

Morphological variation analysis on escaped Nile tilapia from main aquaculture areas in Guangxi

Objective]This research was conducted to elucidate the effects of geographical habitat on morphological variation of escaped Nile tilapia to provide reference for future study of tilapia population invasion and formulation of con-trol strategy.Method]The one-year-old male escaped N. tilapias from six main aquaculture areas(Yulin,Nanning,Qin-zhou,Guigang,Fangchenggang and Beihai)in Guangxi were collected. Morphological characteristics and multivariate morphometrics were analyzed by morphometry,principal component analysis,discriminant analysis and cluster analysis.Result]In terms of full length,body length,body height,head length,snout length and body weight,N. tilapias from Yulin were the largest while those from Qinzhou the smallest,and significant difference was observed between tilapias from the two areas(P<0.05). In principal component analysis,the contribution rates of top three principal components were 74.31%,9.23%and 6.21%,cumulative contribution rate reached 89.75%,which summarized growth characteristics of wild escaped N. tilapias in different aquaculture areas. Discriminant analysis showed that N. tilapias from different aquaculture areas could be distinguished by using discriminant function established based on seven morphological charac-teristics including full length,body thickness,head length,snout length,eye diameter,eye distance and body weight, and the discriminant accuracy was 96.11%. Cluster analysis suggested that the N. tilapias in Qinzhou had the lowest simi-larity with those from other regions but the largest variation,and thus appeared as a single clade. The correlations between body weight and full length,body length,body height,body thickness,head length,snout length,eye diameter and eye distance were extremely significant(P<0.01). Thereinto,correlation coefficients between body weight and full length, body length and body height were high,reaching 0.9375,0.9359 and 0.8327 respectively,but its correlation coefficient with eye diameter was the lowest(0.5947).Conclusion]Principal component analysis and discriminant analysis are feasi-ble methods to distinguish the source of escaped tilapia. Analysis on full length,body length and body weight of escaped N. tilapia can be helpful for understanding its living condition and provide reference for controlling tilapia invasion.