Morphological variation in the common lancehead populations: sexual dimorphism and ontogenetic patterns

Abstract

The common lanceheadBothrops jararacais widespread in the Atlantic Forest inBrazil. The species is known to show a marked sexual dimorphism pattern, with thefemale being larger than the male. However, most efforts in clarifying morphologicalvariation between the sexes are often focused on a single population. In this paper,we investigate how sexual dimorphism and ontogenetic trajectories vary among pop-ulations as well as the ontogenetic trajectories ofB. jararaca. We analyzed 211 spec-imens from a coastal and a highland population and measured 17 morphologicaltraits, including linear and meristic characteristics, and the analysis revealed a clearbut variable effect of sex and population. Females were larger than males in all eval-uated populations. Furthermore, females in the coastal population were generallysmaller than in the highland population but had significantly more scales. Widespreadspecies often experience differential environmental pressures even in terms of bioticand abiotic factors. We attribute the results found herein to specificities in prey avail-ability and climatic conditions which affect the ontogenetic pattern between the sexesand the populations, resulting in specific sexual dimorphism patterns.