Lifetime selection on adult body size and components of body size in a waterstrider: opposing selection and maintenance of sexual size dimorphism.

摘要: Sexual size dimorphism (SSD), the difference in body between males and females, is common almost all taxa of animals generally assumed to be adaptive. Although sexual selection fecundity alone have often been invoked explain evolution SSD, more recent views indicate that sexes must experience different lifetime pressures for SSD evolve maintained. We estimated acting on male female adult (total length) components waterstrider Aquarius remigis during three phases life history. Opposing overall occurred separate episodes fitness females both years one year. Specific were targets size. When net was by combining each individual's fitnesses from episodes, we found stabilizing sexes. In addition, optimum smaller than females. However, even when had experienced opposing individual no appeared under selection. This first evidence contemporary a natural population acts maintain larger size, most pattern nature.