Allometry for sexual size dimorphism: pattern and process in the coevolution of body size in males and females
Annual Review of Ecology and Systematics 28: 659-687
Sexual size dimorphism (SSD) is reviewed. Common in both plants and animals, SSD probably reflects the adaptation of males and females to their different reproductive roles. Data from 40 independent clades of terrestrial animals, mainly vertebrates, indicate that SSD tends to increase with body size when the male is the larger sex but decrease with size when females are larger--Rensch's rule. The extension of this rule to plants and aquatic animals will require quantitative allometric assessments of SSD within these groups. Many functional hypotheses have been developed to explain the evolution of allometry for SSD, but one stands out: that allometry evolves because of correlational selection between the sexes. Despite its promise, however, this hypothesis remains untested.