中国林蛙两性异形及其与繁殖的适应

Sexual dimorphism adapted to reproduction in Rana chensinensis

通过对中国林蛙(Rana chensinensis)成体雌雄各60例样本的11项形态指标的测量,分析该物种的两性异形特征,探讨产生两性异形的机制.结果表明,雌性的体长(t=3.94,df=118,P<0.001)和体重(t=5.61,df=118,P<0.001)显著大于雄性;协方差分析表明,雄性的头长、头宽、鼻间距、眼间距、眼径、鼓膜径、前肢和后肢长度均显著大于雌性;雌雄两性的吻长(F1,118=2.76,P=0.84)差异不显著.回归分析表明,两性的头长、头宽、耳径等局部特征均与体长呈正相关.去除体长差异,对10个形态指标的主成分分析表明,前3个主成分共解释74.308%的变异,第1主成分中头长、头宽、鼻间距、眼间距、前肢长和后肢长、第2主成分中体重、第3主成分中眼径和鼓膜径分别有较高的负载系数.研究结果表明,中国林蛙存在局部形态的两性异形,雌性具有较大的体型与繁殖力选择相关,雄性的头部较大、肢体较长可能与性选择和自然选择相关.

Based on measuring 11 morphological characteristics of 60 female and 60 male adult frogs which were collected from the Qinling Mountains, China, the mechanism of sexual dimorphism of Rana chensinensis was studied. The results showed that the snout-vent length （SVL） （t=3.94, df=118, P（0. 001） and body mass of females（t=5.61, df=118, P〈0. 001） are larger than that of males. The ANCOVA analysis indicated that the head length, head width, internasal length, interocular length, eye diameter, tympanum diameter, fore-limb length and hind-limb length of males are significantly lager than that of females. The snout length（F1,118 = 2.76, P=0.84） for males is not differ between males and females. It is indicated by regression analysis that head length, head width, tympanum diameter and other characters of frogs positively correlate with SVL. A principal component analysis generated three components （with eigenvalue E≥1） from ten size-free morphological variables, accounting for 74. 308 % of variation in the original data. The first component （51. 539% variance explained） has high positive loading for size free values of head length, head width, internasal length, interocular length, fore-limb length and hind-limb length, the second component （14. 045%） for size free value of body mass, and the third component （8. 723%） for size free values of eye diameter, tympanum diameter. The results indicated that partial sexual dimorphism exists in Rana chensinenis, female clutch size and fecundity, and therefore reproductive success, typically increased with female body size. The other distinct morphological characteristics in males are relative to sexual selection.