摘要
比较金线侧褶蛙和泽陆蛙的两性异形和生育力,首次通过种间比较来验证生育力选择理论是否能解释两栖动物两性异形的进化。金线侧褶蛙和泽陆蛙均为雌体大于雄体的两性异形类型,其两性异形程度存在显著差异,金线侧褶蛙两性异形程度指数为0 .30 ,而泽陆蛙仅为0 .0 8。然而,两者的怀卵量无显著差异。因此,结果与生育力选择理论预测不一致。此种不一致性可能由下述原因导致:选择压力作用于雄体而非雌体、能量分配策略和死亡率的种间差异、以及系统发育历史的种间差异。金线侧褶蛙和泽陆蛙雄体的身体状态指数显著高于雌体。金线侧褶蛙的头,眼和四肢都显著大于泽陆蛙;两者雌体的前后肢长度显著大于雄体。两性金线侧褶蛙的前后肢随体长呈同速生长。
The fecundity selection” hypothesis has been used to explain why females grow larger than males in many animal species. To test whether this hypothesis is able to explain inter-specific differences in sexual dimorphism, we compared sexual dimorphism and female fecundity of two species of frogs, the gold-stripe pond frog (Pelophylax plancyi) and the terrestrial frog (Fejervarya limnocharis), in eastern China. In May 2002, 93 terrestrial frogs (51 males, 42 females) and 104 gold-stripe pond frogs (28 males, 76 females) were captured from Hangzhou, Zhejiang Province. The animals were weighed to the nearest mg and measured to the nearest mm for snout-urostyle length, head length and width, diameter of eye, and limb length. Clutch sizes were also determined by counting eggs inside the females. The snout-urostyle length of adult females was significantly larger than that of adult males in both species. Although the degree of sexual size dimorphism differed remarkably (0.30 in P. plancyi and 0.08 in F. limnocharis), clutch size was similar between the two species after the effects of female body size (snout-urostyle length) were statistically removed. Therefore, our results are not consistent with the fecundity selection hypothesis. This outcome may not necessarily mean that fecundity selection does not affect the evolution in sexual dimorphism in amphibian. Firstly, a comparison between two species is not enough to draw general conclusions. Secondly, other causes, which we were not able to test in the current study, could be responsible to failure of the fecundity selection hypothesis to predict the sexual dimorphism in these two species. These causes include selection pressures that affect males rather than females, interspecific differences in energy allocation or mortality rates, and the unknown phylogenetic history of the two species. Moreover, we found interspecific and between-sex differences in body condition and morphology in P. plancyi and F. limnocharis. In the reproductive season, females had lower body condition than males in both species. Gold-stripe pond frogs had larger heads, eyes and limbs than did terrestrial frogs when we statistically controlled for snout-urostyle length. In both species of frogs, limb length was larger in females than in males. Males and females showed different allometric growth patterns in limb length of F. limnocharis, as females grow faster than do males; this sex difference does not occur in P. plancyi.
出处
《生态学报》
CAS
CSCD
北大核心
2005年第4期664-668,共5页
Acta Ecologica Sinica
基金
杭州市新世纪优秀中青年人才基金资助项目~~
关键词
金线侧褶蛙
泽陆蛙
两性异形
窝卵数
生育力选择
Pelophylax plancyi
Fejervarya limnocharis
sexual dimorphism
clutch size
fecundity selection
