Breaking the rule: multiple patterns of scaling of sexual size dimorphism with body size in orthopteroid insects

ELIO RODRIGO CASTILLO; ALBERTO TAFFAREL; CLAUDIO JUAN BIDAU

REVISTA DE LA SOCIEDAD ENTOMOLóGICA ARGENTINA

SOCIEDAD ENTOMOLÓGICA ARGENTINA

Lugar: Mendoza; Año: 2016 vol. 75 p. 11 - 36

0373-5680

Sexual size dimorphism (SSD) although a widespread phenomenon among animals, is both enigmatic as to its proximate and ultimate causes and the scaling relationships between SSD and body size (Rensch?s rule). We analyzed SSD at the intra- and interspecific levels in a number of representative species and genera of the major orthopteroid orders: Orthoptera, Phasmatodea, Mantodea, Blattodea, Dermaptera, Isoptera, and Mantophasmatodea. The vast majority of the species showed female biased SSD but numerous exceptions occur in cockroaches and earwigs. Rensch?s rule and its converse are not common patterns at both, intraand cross-species level, most species and genera showing an isometric relationship between male and female body sizes. In some but not all cases, the demonstrated allometric patterns could be related to geographic body size variation. We also showed that not all body size estimators produce the same degree of SSD and that dimorphism can be strongly influenced by a number of living conditions and the patterns of nymphal development. Finally, we discuss our results in relation to current models of the evolution of sexual size dimorphism in animals.