山地麻蜥个体发育过程中头部两性异形和食性的变化

研究了山地麻蜥(Eremias brenchleyi)个体发育过程中头部两性异形和食性的变化．成体个体大小(SVL)无显著的两性差异，但雄体具有较大的头部(头长和头宽)．头部两性异形在孵出幼体就已存在，成体头部两性异形比幼体(包括孵出幼体)更为显著，雄性较大的头部与其头部随SVL的增长速率大于雌性有关．两性头部总体上随SVL呈异速增长，表现为个体发育过程中头长和头宽与SVL的线性回归方程斜率有显著的变化．孵出幼体有相对较大的头部，这种形态特征是胚胎优先保证生态学意义更为显著的头部生长的结果，有利于孵出幼体的早期生存和生长．相对头部大小在个体发育过程中有显著的变化．不同性别和大小的山地麻蜥摄入食物的种类及各种食物在摄入食物中所占的比例有一定程度的差别，食物生态位宽度和重叠度因此有一定的差别．然而，没有直接的证据表明头部两性异形能导致两性食物生态位的明显分离，并有利于减缓两性个体对食物资源的竞争。

Ontogenetic shifts in sexual dimorphism in head size and food habits of Eremias brenchleyi

Studies on the ontogenetic shifts in sexual dimorphism in head size (head length and width) and food habits of Eremias brenchleyi were studied. The results showed that adult E. brenchleyi had no obvious sexual dimorphism in body size (SVL). Both sexes differed in head size since hatching, with males having larger heads than females. This sexual dimorphism was much more pronounced between adults than between juveniles (including hatchlings), largely because the increase velocity of head size of males with SVL was faster than that of females. Hatchlings had relatively larger heads to SVL than juveniles and adults, presumably because E. brenchleyi embryos allocated relatively more resources for early survival and growth of hatchlings. Head size of both sexes overall showed an allometric growth pattern with SVL increase ontogeny.Lizards of different sizes and sexes differed, in certain degrees,in food niche breadth and niche overlap. However, no direct evidence showed a noticeable contribution of the divergence in head size to the segregation of food niche between males and females, thereby mitigating the competition between both sexes.