Understanding the genetic architecture [e.g.,the number,location,and effect of quantitative trait locus (QTL)] of ecologically important traits is crucial for exploring wildlife adaptation and evolutionary dynamics.The common frog (Rana temporaria) is one of the most widely distributed amphibians in Europe and many traits such as body length,body size and time and at metamorphosis displayed a latitudinal divergence across the Scandinavian peninsula.It is also an especially interesting model for the study on genetic basis of temperature-dependent and sexual dimorphism in complex traits.In this study,we created an artificial full-sib cross (n = 800 individuals) between the parents from south and north Sweden,where the common frog populations were known to be phenotypieally divergent in respect to the traits of interest,and the two halves of the full-sibs were reared in two environmental temperatures,16℃ or 21℃,separately.We scanned for QTLs associated with the traits of body weight,body length and the time of metamorphosis with the aid of 92 autosomal and sex-linked microsatellites.We were also interested in the effects of sex and the environmental temperature on phenotypes of these traits.Phenotypic analysis showed that body weight and metamorphosis time,but not body length,are significantly (P < 0.001) different between the two environmental temperatures.We also detected significant (P < 0.05) sexual difference for the timing of metamorphosis under 21℃.QTL mapping analysis indicated two significant (P < 0.05) QTLs for body weight,one at 71 cM on LG3 and another at 5 cM on LG8.Meanwhile,significant QTLs for timing of metamorphosis were mapped on four linkage groups (LG 2,P < 0.01; LGs 6,8 and 14,P < 0.05).Several QTLs for the traits were mapped within the sex under either of the temperatures,In 16℃,five significant QTLs for the three traits were mapped on four LGs (LG7,LG10,LG2 and LG8) in male and two significant QTLs,one for body weight and another for metamorphosis time,were mapped on LG3 and LG8,respectively in female.In 21℃,only one significant QTL was observed on LG6 for metamorphosis time in male; two significant QTLs for metamorphosis time and one QTL for body length,which mapped to LG7,LG14 and LG9,respectively,were observed in the female only.Our results provide the first QTL-scan in the common frog with focus on the three traits,and open a possibility to progress our understanding of the underlying genetic architecture of these divergent traits in the common frog as well as other amphibians.