宁波滑蜥两性异形和雌性繁殖

蜥蜴的雌性繁殖特征对理解两性异形的进化原因起着重要作用。于2011年4月在安徽滁州采集宁波滑蜥(Scincella modesta),定量研究该种形态特征的两性异形和雌性繁殖特征,检验成体形态特征两性异形与雌性繁殖的相关性。研究共采集43条(17♀♀,26♂♂)宁波滑蜥,雄性和雌性个体的最大体长分别为47.4 mm和46.6 mm。雌雄两性在体长和头宽上没有差异,而在腹长和头长上差异显著,雄性有较大的头长,雌性有较大的腹长。宁波滑蜥年产单窝卵。窝卵数和窝卵重与雌体体长及腹长呈正相关,卵重与雌体体长无相关性。窝卵数及卵重的变异系数分别为0.20和0.12。卵长径与窝卵数呈负相关,而卵短径与窝卵数无关。雌体主要通过增加窝卵数来增加繁殖输出。这些结果表明,宁波滑蜥是雌雄个体大小同形的两性异形模式,性选择使得雄性有着较大的头长,以具有较高的交配成功率,生育力选择使得雌性有着较大的腹长,以具有较大的生育力和繁殖输出。

Sexual Size Dimorphism and Female Reproductive Output in Slender Forest Skink,Scincella modesta

Data on female reproductive traits can be crucial to understanding the evolutionary causes of sexual size dimorphism(SSD)of lizards.Here we quantified SSD and female reproductive traits to identify potential associations between SSD and female reproduction in Scincella modesta.We collected 43(17 ♀ ♀,26 ♂ ♂)S.modesta in this study,the largest male and female were 47.4 mm and 46.6 mm in snout-vent length(SVL),respectively.Adults are sexually dimorphic in head length and abdomen length but not in body size or head width,with males were larger in head length,whereas females were larger in abdomen length.Females produced single clutch of eggs during the breeding season.Clutch size and clutch mass were positively correlated with maternal SVL and abdomen length,whereas egg size was not positively correlated with maternal SVL.The coefficient variation of clutch size and clutch mass was 0.20 and 0.12,respectively.When holding female SVL constant using a partial correlation analysis,egg length was negatively related to clutch size,egg width was independent with clutch size.These results suggest that S.modesta is a species with sexually monomorphic SSD,sexual selection and fecundity selection,in which males have larger head length for higher mating success and females have larger abdomen length due to their higher capacity for laying eggs.