Reproduction and sexual dimorphism in two populations of the polymorphic spiny lizard Sceloporus minor from Hidalgo, México

Ram�irez-Bautista, A., Stephenson, B.P., Serrano Mu~ C., Cruz-Elizalde, R. and HernU. 2014. Reproduction and sexual dimorphism in two populations of the polymorphic spiny lizard Sceloporus minor from Hidalgo, M� — Acta Zoologica (Stockholm) 95: 397-408. Male-biased sexual dimorphism is extensive in New World spiny lizards (Scelopo- rus: Phrynosomatidae) and is particularly prominent in the polymorphic minor lizard Sceloporus minor. However, the possible relationship between patterns of sexual dimorphism and gonadal development is little known for most species. In this study, we explored aspects of sexual dimorphism in noncolor morphological traits in S. minor and characterized the gonadal cycle in males and females from each of two sites (El Enzuelado and La Manzana) in Hidalgo, Mdiffering in key ecological aspects linked to life-history trait expression in other lizards. Males were generally larger than females in each population and expressed larger forms of several other morphological traits, although not all comparisons attained statistical significance. Both sexes attained reproductive maturity at a larger size in El Enzuelado relative to La Manzana, and females from El Enzue- lado had larger litters. Gonadal cycles differed substantially between the two populations and suggest that reproductive activity of males and females was synchronous at El Enzuelado and asynchronous at La Manzana, an unusual pattern. Geographic variation in sex-specific responses to environmental vari- ables may be at least partly responsible for the exceptional species diversity of spiny lizards in M�