BREEDING, POPULATION-DYNAMICS AND HABITAT RELATIONSHIPS OF SMINTHOPSIS-DOLICHURA (MARSUPIALIA, DASYURIDAE) IN SEMIARID SHRUBLANDS OF WESTERN-AUSTRALIA

Demographic data were gathered from two populations of the little long -tailed dunnart, Sminthopsis dolichura, inhabiting semi-arid nature re serves in the Western Australian wheatbelt in order to place the ecolo gy of this species (formerly part of the Sminthopsis murina complex) i n perspective. In all respects, S. dolichura is similar to S. murina f rom south-eastern Australia, and, indeed, to most other species of the Sminthopsis group. High mobility and transiency rates, an extended se asonal pattern of reproduction, relatively rapid development of the yo ung and the probable existence of polyoestry characterise the life his tory of S. dolichura and most other species within the group that have been studied. These attributes enable a high degree of reproductive f lexibility and permit these species to opportunistically invade new ha bitats and ephemeral post-fire seral stages. The observed sympatry wit h highly seasonal monoestrous dasyurids of the genus Antechinus is pos tulated to occur through spatial and temporal selection of different m icrohabitats, but also suggests that phylogenetic factors may be at le ast as important as the predictability of climate and food resources i n explaining the evolution of different reproductive strategies.