基于椭圆傅里叶分析的次南极电灯鱼矢耳石形态多样性

次南极电灯鱼矢耳石形态特征具有多样性.为了深入研究其形态特征,利用南设得兰群岛外侧水域采集的456尾次南极电灯鱼(体长范围6.0～8.8 cm)样本,对其矢耳石形态进行分析和判别.根据形态特征将次南极电灯鱼耳石分为4种类型,并采用椭圆傅里叶分析法选取表征耳石类型的77个傅里叶特征系数进行了分析.结果表明: 对4种耳石类型两两比较后发现,具有显著性差异的傅里叶特征系数最多及最少分别占总体的61%和28.6%;对77个傅里叶系数进行主成分分析,前22个主成分解释了总变异的76.6%;选取了17个傅里叶特征系数进行判别分析,建立判别函数,总体判别率为87.2%;根据椭圆傅里叶分析重建的耳石轮廓反映了4种耳石类型间的差异.4种耳石类型在不同体长及体质量的次南极电灯鱼中皆有出现,表明耳石类型具有随机性,且左右耳石类型不一致,表明其左右耳石外形具有差异性.4种耳石类型中,Ⅰ型和Ⅱ型占总体的72.6%,为次南极电灯鱼耳石的主要形态;Ⅲ型和Ⅳ型占总体的27.4%,为次要形态.

Otolith morphological diversity of Electrona carlsbergi based on elliptical Fourier analysis.

The otolith of Electrona carlsbergi has diverse morphological characteristics. In order to further study the morphological diversity, a total of 456 sagittal otoliths of E. carlsbergi (standard length 6.0-8.8 cm), which were collected off the South Shetland Islands, were observed and discriminated. The otoliths of E. carlsbergi were classified into four types based on the morphological characteri-stics, and 77 Fourier feature coefficients of four types were analyzed by elliptical Fourier analysis. Based on the pairwise comparison on Fourier feature coefficients of four types, the proportions of pairs of coefficients with significant differences accounted for 61.0% (highest) and 28.6% (lowest) of the total, respectively. Based on the principal component analysis (PCA) of 77 Fourier coefficients, the cumulative contribution rate of first 22 principal components was 76.5%. 17 Fourier feature coefficients were selected to conduct the stepwise discriminant analysis (SDA), and the total discriminated rate was 87.2%. The contours reconstructed by the elliptical Fourier analysis distinctly reflected the differences among the four types of otolith. Four types for E. carlsbergi’s otoliths which appeared on various fish sizes and body masses indicated that the appearance of otolith types was stochastic. The types of otolith were not consistent in the left and right otoliths, indicating different types occurred between both sides of the otoliths. Types I and II were the main forms of E. carlsbergi otoliths, accounting for 72.6% of the total, while types III and IV were the secondary forms, accounting for 27.4% of the total.