Catch‐up growth in the rhinoceros beetle Trypoxylus dichotomus (Coleoptera: Scarabaeidae): Smaller neonates gain relatively more body mass during larval development

Body size often varies among conspecific neonates. As larger adults generally have higher fitness than smaller conspecifics, it is adaptive for smaller neonates to subsequently gain relatively more size increments during larval development (catch‐up growth). Although catch‐up growth has been suggested in insects, inappropriate methods have been used to examine the size dependence of growth increments. Therefore, it remains unclear to what extent catch‐up growth is common among insects. The present study examined the size dependence of growth increments among larvae of Trypoxylus dichotomus using reduced major axis regression of final to initial body masses. Catch‐up growth was found consistently for larval instars. Furthermore, simulations of the size increments revealed that not only sexual divergence of the mean size, but also catch‐up growth within sexes plays a role in the development of sexual divergence in the body size distribution of T. dichotomus . The significance of catch‐up growth in body size evolution was discussed.