It is now appropriate to examine the variation or adaptations which species exhibit within the constraints of being marsupial. Because of the effect of diet on growth and fecundity we will separate the marsupials into those species which feed predominantly upon animal tissue, the polyprotodont marsupials (this chapter), and those species which feed predominantly upon plant material, the diprotodont marsupials (Chapter 5). We have argued that the protein- and energy-rich diet of carnivorous species facilitates growth and reproduction, so in these taxa we might expect comparatively large litters and short periods of maternal investment, subject to the allometric constraints we have discussed previously. The abundance of some animal prey varies seasonally (e.g. arboreal insects; Chapter 2) and unpredictably (e.g. desert foliage-feeding insects) and we would expect this variability to have a strong influence in shaping the life histories of carnivores.

Dasyuridae

Despite their conservative body form and diet, the Dasyuridae have been exceptionally successful in Australia and New Guinea in the range of habitats occupied (Chapter 2), and this success is reflected in the wide range of life history strategies they exhibit. This diversity of life history strategies has aroused considerable interest because of the opportunities it offers for empirical analysis of life history theory (see Chapter 6). A review of these life histories by Lee, Woolley & Braithwaite (1982) recognised six distinct strategies among the thirty species for which there was information on patterns of reproduction and longevity. The strategies were distinguished on the basis of five characters (Fig. 4.1): the frequency of oestrus, the duration and the timing of male reproductive effort, the seasonality of breeding and the age at maturity.