Condition-and context-dependent variation of sexual dimorphism across lizard populations at different spatial scales

The evolution of sexual dimorphism (SD) is driven by intricate interplays between sexual and naturalselection. When it comes to SD variation within populations, however, environmental factors playa major role. Sexually selected traits are expected to be strongly dependent on individual bodycondition, which is infuenced by the local environment that individuals experience. As a consequence,the degree of SD may also depend on resource availability. Here, we investigated the potential driversof SD expression at two sexually dimorphic morphometric traits, body size (snout vent length) andhead shape (head geometric morphometrics), in the Italian wall lizard (Podarcis siculus). We assessedthe existence of condition- and context-dependent SD across ten islands of the Aeolian archipelago(southern Italy), at within- and among-population scales. We observed strong geographical variationof SD among islands, and tested three potential SD predictors related to resource availability(individual body condition, ecosystem productivity, temperature). Body condition and ecosystemproductivity were the main drivers of body size SD variation, and body condition was also the maindriver for head shape SD. Our results highlight that the expression of SD in the Italian wall lizardis both condition- and context-dependent. These results are congruent at within- and amongpopulations scales highlighting that spatial multi-scale analysis represents a useful approach tounderstand patterns of SD expression.