Growth,Sexual Size Dimorphism and Female Reproduction of Blue tailed Skinks,Eumeces elegans

We report data on growth,sexual dimorphism and female reproduction for bluetailed skinks,Eumeces elegans,from a population in Hangzhou,Zhejiang,eastern China.All the animals were captured from the field and then raised in the laboratory.The body and head sizes of 449 skinks were measured to indicate ontogenetic changes in sexual size dimorphism.The growth of 94 juveniles and 50 adults and the reproductive output of 12 adult females were determined.We pay particular attention to the point during ontogeny at which males and females diverge in body size (SVL) and head size (length and width) and the way through which females increase their reproductive output.Adults were sexually dimorphic in coloration,body size and head size,with male adults being larger in both body and head size than female adults.Newly emerged young did not show sex difference in SVL,and male and female juveniles (SVL <69.3 mm) exhibit isometric growth pattern of SVL.Male and female adults (SVL >69.3 mm) showed allometric growth pattern of SVL,as male adults grew faster than female adults.Therefore,It was concluded that sexual dimorphism in body size of E.elegans occurred only in adults.Our data revealed that male and female juveniles larger than 50 mm SVL began to diverge in head size,with males having larger heads than females.This sexual dimorphism resulted from the greater head growth rate relative to SVL in males when their SVLs were larger than 50 mm SVL,and became increasingly pronounced in adults.The sexual dimorphism in body and head size suggested that the strategy of energy partition of adult males and females was different.Adult males partition relatively more energy into body and head growth so as to improve the reproductive fitness,in contrast,adult females partition relatively more energy into reproductive investment other than body growth.Morever,adult females pa rtition relatively less energy into head growth but more into carcass growth,thereby leaving a larger space for containing more eggs.The smallest reproductive female in our sample is 69.3 mm SVL,and all females larger than this size lay a single clutch of eggs per breeding season.Clutch size,clutch mass and clutch mean egg mass were all positively correlated with maternal SVL,with average 6.4 eggs,2.783 g and 0.554 g,respectively.Females of E.elegans increase reproductive output mainly through increasing clutch size (egg number) and egg size as well.