Growth and Sexual Dimorphism in the Dibbler, Parantechinus apicalis (Marsupialia, Dasyuridae)

Abstract

Sexual dimorphism in animals has been recognised as being associated with particular breeding strategies or mating systems since Darwin's Origin of Species. Frequently, in polygamous situations, females express a variety of attributes to attract males, and males compete with each other for access to females. This produces different selective pressures in each sex, which in tum produces differing morphologies (Leigh 1995). Thus, the emphasis of morphological studies of sexual differences tends to focus on adults and not the growth patterns that generate those differences. Growth patterns in marsupials have been shown to be variable between species (Gemmell and Hendrikz 1993). Previous studies of dasyurid species in captivity concluded that the onset of dimorphism occurs prior to or during weaning (Whitford, Fanning and White 1982; Williams and Williams 1982), but wild animals are not sexually dimorphic until after weaning (Soderquist 1995). These studies have generally examined the growth rates of males and females and the timing of the onset of sexual dimorphism, but little attention has been focussed on how the differences between the sexes are generated.