Ejaculate size in bushcrickets: the importance of being large

Abstract

AbstractSexual size dimorphism is common in animals. Females, which often experience increased fecundity with size, are generally the larger sex. In males, the pre‐copulatory advantages of large size have been extensively investigated. However, in polyandrous species, large male size may also be advantageous after copulation due to sperm competition. Male size co‐varies with ejaculate size and increased fertilization success in many insects. Large male size can also be important for production of nuptial gifts enhancing female fecundity. In this study, the relative importance of male size for ejaculate and nuptial gift production is assessed in 20 bushcricket species (Orthoptera: Tettigoniidae). Relative male size is found to correlate with increased ejaculate size across taxa. In contrast, no association is found between relative male size and the size or quality of the nuptial gift. These findings indicate that selection for increased ejaculate volumes as a response to sperm competition may act to promote large male size in insects.