沙塘鳢形态特征的两性异形和雌性个体生育力

Sexual Dimorphism in Morphological Traits and Female Individual Fecundity of Odontobutis obscurus

测定了沙塘鳢繁殖期形态特征包括体长、头长、头宽、头高、吻长、眼后头长、眼径、眼间距、体高、尾柄长、尾柄高、尾鳍长、背鳍基前距、背鳍基长、背鳍间距、腹鳍基前距、腹臀间距、体重和去内脏体重的两性异形和雌性个体生育力。结果表明,繁殖季节雄性个体的数量显著少于雌性个体,雄性个体的体长显著大于雌性个体。特定体长的雌性个体的头长、头宽、头高、眼间距、尾柄高、背鳍基长、去内脏体重显著小于雄性个体,体高、背鳍间距和腹臀间距显著大于雄性个体。两性其他局部特征不存在显著的差异。10个形态特征变量的主成分分析(Eigenvalue≥1)发现,前3个主成分共解释61.6%的变异。头长、头高和躯干重在第一主成分有较高的正负载系数(解释26.9%变异),背鳍基长在第二主成分有较高的正负载系数,背鳍间距在第二主成分有较高的负负载系数(解释18.3%变异),体高和腹鳍臀鳍间距在第三主成分有较高的正负载系数(解释16.4%变异)。雌性在第一、第二主成分的分值显著小于雄性,在第三主成分的分值显著大于雄性。怀卵数量与体长和体重回归关系显著。偏相关分析表明,怀卵数量与体重呈显著的正相关,与体长呈显著的负相关。雌性通过个体大小特别是体重的增长以及腹腔体积的增加来提高个体生育力,增加繁殖输出。

We measured the sexual dimorphism in morphological traits, ineludiug the body length, head length, head width, head depth, snout length, postorbital head length, eye diameter, iaterorbital width, body depth, caudal peduncle length, caudal peduncle depth, caudal fin length, dorsal fin precoxal length, dorsal fin coxal length, length between dorsal fin, pelvic fin prccoxal length, length between pelvic fin and anal fin, body mass, carcass mass of the Odontobitis obseurus in reproductive season from Caoejiang River, Shangyu City, Zhejiang Provinee. It had been found that the number of adnlt males was larger than that of females and the body length of adult females was significantly shorter than that of aduh males. The females with special body length were significantly shorter than the males in head length, head width, head depth, interorbital width, caudal peduncle depth and dorsal fin coxal length, carcass mass of adult females were significantly smaller than those of adult males, while the former were significantly larger than the latter in body depth, dorsal fin spacing, length between pelvic fin and anal fin. There was no significant sexual difference among other morphological traits. A principal component analysis resolve three componenls （with eigenvalnes ≥ 1） from ten size （body length）-frec morphological variables, accounting for 61.6% of variation in the original data. The first component （26.9% variance explained） had high positive loading for size-free values of head length, head depth and carcass mass, the second component （18.3% variance explained） had high positive loading for size-free value of dorsal fin coxal length, and had high negative loading tot size-free value of length between dorsal fin, the third component （16.4% variance explahled） had high pcsitive loading for size-free value of body depth and length between pelvic fin and anal tin. Females had significantly lower scores on the first and second axis, but had larger scores on the third axis of a prineipal component analysis than did males. The individual fecundity was significantly posltively correlaled with the body length and body mass in O obscurus. A partial correlation analysis showed that the individual fecundity was positively correlated with body mass and negatively correlated with the body length when the third invariableness was in control. A conclusion has been drawn that aduh females increase the individual fecundity through increasing the individual size （especially through increasing the body mass） and eapaeily of abdominal cavity, thus increasing reproduction output.