Abstract
In a model group of giant reptiles, we explored the allometric relationships between male and female body size and compared the effects of sexual and fecundity selection, as well as some proximate causes, on macroevolutionary patterns of sexual size dimorphism (SSD). We analysed data concerning the maximum and/or mean male and female snout-vent lengths in 42 species of monitor lizard from literary sources and supplemented these data with measurements made in zoos.
There was a wide scale of SSD from nearly monomorphic species belonging mostly to the subgenus Odatria and Prasinus group of the Euprepriosaurus to apparently male-larger taxa. The variable best explaining SSD was the body size itself; the larger the species, the higher the SSD.
This pattern agrees with the currently discussed Rensch‘s rule, claiming that the relationship between male and female body size is hyperallometric.