Behaviour 2019
Is condition dependence the underlying mechanism for the emergence of Rensch’s rule?
SOLIMARY GARCIA-HERNANDEZ, GLAUCO MACHADO. Universidade de São Paulo, São Paulo, SP, Brazil

In many species sexual dimorphism increases with body size when males are the larger sex but decreases when females are the larger sex, a macro-evolutionary pattern known as Rensch’s rule (RR). Although empirical studies usually focus on body size, Rensch’s original proposal included sexual differences in other traits. In fact, recent studies with arthropods demonstrated that RR also applies to condition-dependent male traits, such as ornaments and weapons, highlighting the role of sexual selection in the emergence of RR. However, a strong mechanistic link between condition dependence and RR is still lacking. Moreover, if the RR also applies to a micro-evolutionary scale, i.e., populations of the same species is still a poorly explored question. Here we studied 20 populations of the earwig Labidura xanthopus along a latitudinal range of 30°. In a controlled laboratory experiment, we first evaluated the level of condition dependence of several traits. Then we tested if each trait we measured follows RR. Our hypothesis is that male traits with high levels of condition dependence will follow the RR, while male traits with low levels of condition dependence will not.