摘要In order to tease apart proximate vs.ultimate sources of variation in reproductive strategy,studies have increasingly focused on populations rather than species as the unit of interest.The reproductive parameters of Phrynocephalus przewalskii(Agamidae)in different populations within the same phylogenetic clade were compared in this study.Female SVL,clutch size,egg volume and clutch volume varied significantly among populations.With increase in latitude,clutch size increased,while egg size decreased.Relatively fewer but larger eggs were produced with increasing of population density.Food availability had positive effects on clutch size,but no effect on egg size.Our result indicated that latitude,food availability and population density may be the proximate factors affecting the reproductive parameters of P.przewalskii