利用几何形态测量学方法分析唐鱼群体的形态变异

Geometric morphometric analysis of body-form variability in populations of Tanichthys albonubes

摘要:

唐鱼是华南地区小型亚科鱼类的典型代表，国家Ⅱ级保护水生野生动物。本研究利用基于地标点的几何形态测量学方法分析了唐鱼8个野生种群和2个养殖群体的形态变异，旨在从形态学的角度了解唐鱼不同种群间的分化程度，为唐鱼保护策略的制定提供科学依据。新鲜标本冰冻麻醉后随即置于95%酒精中固定，用Nikon D-800单反相机拍照获得固定标本的标准图像。利用tps系列软件提取地标点坐标值，进行相对扭曲主成分分析、网格变形分析和判别分析来解释唐鱼的形态变异。相对扭曲主成分分析结果显示，第1、2、3主成分分别解释了总变异的48.20%、23.12%和14.83%，降维效果较好。其中，Ⅱ型地标点12、13、14和15贡献较大，四者合计贡献率达71.28%，反映出唐鱼群体的形态变异主要表现在眼径大小和头部形态。逐步判别分析和交互验证分析的总体判别正确率分别为97.6%和92.0%，能有效识别唐鱼群体。研究结果还揭示了唐鱼野生种群和养殖群体之间存在显著的形态差异。基于上述结果以及唐鱼呈点状分布的事实，建议将唐鱼的7个野生种群（越南种群除外）各自作为单独的保护单元进行重点保护，同时建议禁止在野外放流养殖群体。

关键词:唐鱼;形态变异;几何形态测量学;相对扭曲主成分分析;网格变形分析;保护策略

Abstract:

Tanichthys albonubes, which was listed as Class Ⅱ protected animal in China's State Key Protected Aquatic Animal List, is a typical representative of the small Danioninae fishes in South China. Aimed at understanding morphological differentiation between populations as well as providing scientific basis for developing conservation strategies of T. albonubes, we investigated the body-form variation using landmark-based geometric morphometric method among 8 wild populations and 2 hatchery populations of T. lbonubes. Frozen anesthetized fresh specimens were then fixed in 95% ethanol, a Nikon D-800 SLR camera was utilized to take standard images of the fixed specimens afterwards. Landmark coordinate values were extracted after samples digitized by image processing and processed by relative warp principal component(RW), grid deformation and discriminant analysis in TPS series software. The 24 RW were then identified using discrimination analysis to differentiate the ten T. lbonubes populations. The result indicated that, the 1 st, 2 nd and 3 rd RW accounted for 48.20%, 23.12% and 14.83% of the total variation respectively, of which type Ⅱ landmarks 12, 13, 14 and 15 had important contributions, and could explain the most variations. The most morphological variations were displayed in eye diameter and head shape. Furthermore, it uncovered obvious morphological variation among wild populations and hatchery populations. Therefore, we suggest that it should be forbidden to release the hatchery populations in filed. Given the results in this study and the punctate distribution of T. albonubes, we also proposal that the 7 wild populations (expect Vietnam) should be regard as 7 management units(MU), respectively.

Key words:Tanichthys albonubes;morphological variation;geometric morphometrics;relative warp principal component;grid deformation analysis;protection strategy