Maternal and genetic correlations between morphology and physical performance traits in a small captive primate, Microcebus murinus

Physical performance traits are key components of fitness and direct targets of selection. Maternal effects are important components of integrated phenotypes in a variety of species. Yet their contribution to variation in performance, and phenotypes closely associated with performance, remains poorly understood. We used an animal model approach to quantify the contribution of maternal effects to performance trait variation (in bite force and pull strength) and the relationships between performance and the relevant underlying morphology in Microcebus murinus. We show that bite force is heritable (h2~0.23), and that maternal effects are also important source of variation, resulting in a medium inclusive heritability (IH2~0.47). Grip strength presented a rather low and non-significant narrow-sense heritability suggesting a higher selective pressure on this trait. Genetic correlations between performance traits and their associated morphometric traits were significant and high (0.47 bite force-head width; 0.48 grip strength-radius length), as was the maternal correlation for bite force-head width (0.75). Further studies evaluating the heritability of performance for other taxa and the role of maternal effects are badly needed to better understand the drivers of variation in performance ultimately allowing for a better understanding of the importance of these types of traits in an evolutionary context.