南海中南部鸢乌贼中型群与微型群形态指标的分析比较

A Study on Morphological Indicators Variations and Discrimination of Medium and Dwarf Forms of Purple Flying Squid Sthenoteuthis oualaniensis in the Central and Southern South China Sea

为了深入认识南海鸢乌贼(Sthenoteuthis oualaniensis)各形态指标与胴长之间的关系,本研究使用254尾微型群个体和3 183尾中型群个体的胴长(ML)、右第一腕长(AL1)、右第二腕长(AL2)、右第三腕长(AL3)、右第四腕长(AL4)、右触腕长(TL)、鳍长(FL)和鳍宽(FW)等形态指标,通过线性、幂和指数等函数模型拟合筛选获得能够反映不同种群雌性和雄性个体各形态指标与胴长关系的最佳模型。建立了以胴长为自变量、各形态指标作为因变量的回归方程。通过赤池信息量准则对模型拟合结果进行检验,结果表明,2个种群雌、雄个体各形态指标和胴长的最优拟合模型都以幂函数曲线模型为主。采用幂函数模型对2个种群各形态性状和胴长关系进行比较发现,中型群雌性与微型群雌性AL1、AL2、AL3、TL、FL与ML的关系式中幂指数差异显著(P<0.05),中型群雌性与微型群雌性AL1、AL2、AL3、AL4、TL、FL、FW与ML的关系式中常数项差异显著(P<0.05);中型群雄性与微型群雄性AL1、AL2、AL3、AL4、TL、FL、FW与ML的关系式中常数项差异显著(P<0.05)。各性状指标随性腺成熟度的增加而增加明显,且雌性增加值大于雄性,中型群增加值大于微型群。鳍长与鳍宽的分析结果表明,2个种群鳍长鳍宽比随鳍长的变化具有差异,且在雄性个体中差异更加明显。综上研究结果表明,南海鸢乌贼个体的形态指标在种群间和性别间存在显著性差异,且各性状指标随性腺成熟度的增加而产生的变化在种群间和性别间也存在差异,对于鸢乌贼的种群鉴别和生物学研究具有一定的参考意义。

In order to know the relationship between mantle length and the other morphometric indicators in the purple flying squid Sthenoteuthis oualaniensis,the morphological indicators including Mantle Length(ML),Arm Length-I(AL 1),Arm Length-Ⅱ(AL 2),Arm Length-Ⅲ(AL 3),Arm Length-Ⅳ(AL 4),Tentacle Length(TL),Fin Length(FL)and Fin Width(FW)of 254 individuals of dwarf form and 3 183 individuals of medium form of S.oualaniensis were measured in this study.The best models for female and male individuals reflecting the relationship between each morphometric indicator and ML were obtained through model fitting screening by linear model,power and exponential and other functional models,respectively.We established the regression equation with morphometric indicators as variables and ML as the dependent variable and calculated the direct and indirect path coefficient and the coefficient of determination.The results of the model fitting test were carried out by the Akaike information criterion.The results showed that the best model fitted for most male and female individuals of two forms was power function.Through comparing two forms power function between mantle length and the other morphometric indicators,the result showed that:Significant differences of coefficient in AL 1-ML,AL 2-ML,AL 3-ML,TL-ML,FL-ML and power exponent in AL 1-ML,AL 2-ML,AL 3-ML,AL 4-ML,TL-ML,FL-ML were identified between the female of medium and dwarf forms(P<0.05).Significant differences of coefficient in AL 1-ML,AL 2-ML,AL 3-ML,AL 4-ML,TL-ML,FL-ML,FW-ML were identified and power exponent in AL 1-ML,AL 2-ML,AL 3-ML,AL 4-ML,TL-ML,FL-ML,FW-ML were not identified between the male of medium and dwarf forms(P<0.05).It is shown that the length of all morphometric indicators increased obviously with the elevation of gonadal maturity,the average rate of female is bigger than male,and the average rate of medium form is bigger than dwarf form.The analysis of fin length and fin width showed that the ratio of fin length and fin width is different with the increasing of fin length between medium and dwarf forms,and the difference is more obvious in male individuals.These results confirm that Significant differences in morphometric indicators between the medium and dwarf forms of males and females were found,and With the growth of gonadal maturity,there were significant differences in morphometric indicators between the medium and dwarf forms of males and females,which can provide a reference for distinguishing the different populations and biological research of S.oualaniensis.