In recent years the study of ecology has undergone a rapid shift in approach. This has been associated with an increased emphasis on evolutionary principles in analysis of ecological relationships. Historically, ecology was biased towards descriptive studies, but now most synthetic ideas are generated from theoretical approaches, often couched in turgid equations which are incomprehensible to biologists who lack mathematical training. Unfortunately, the explosion of mathematical theory has now outstripped the ability of biologists to verify its main predictions empirically. The loose use of the results of theory which may be based on naive assumptions is something of which we should all be careful, and in Chapter 7 we review the growth of competition theory as an example of the inadequate integration of theoretical, experimental and descriptive aspects of science.

A further consequence of these developments has been a decline in the role played by mammals and birds in our understanding of theoretical ecology. Although the ‘fathers’ of evolutionary ecology, David Lack and Robert MacArthur, were both ornithologists, it has become increasingly apparent that invertebrates with simple life histories, simple population structure and short lives are superior empirical tools to most mammals and birds. In this chapter we discuss a fascinating mammalian exception to this pattern. The abrupt male mortality, synchronous breeding and monoestrous reproduction in Antechinus spp. overcomes many of the technical difficulties experienced by population ecologists. Animals may be aged precisely, the distinction between semelparity and iteroparity is clearly defined, and the maternity and survival of young is readily assessed.