WHY ARE TERMITE-EATING AND ANT-EATING MAMMALS SMALLER IN AUSTRALIA THAN IN SOUTHERN AFRICA - HISTORY OR ECOLOGY

Myrmecophages (specialized termite- and ant-eating mammals) are smalle r in Australia than in souther Africa, even where climate and soils ar e similar. For example, the pangolin in southern Africa (like the echi dna in being toothless, armoured and slow in metabolism, movement and growth) is larger than any known Australian myrmecophage, living or ex tinct. This could be the result either of accidents of history or of d ifferent environments on the two continents. Four hypotheses which wou ld support the historical explanation are refuted. There are no phylog enetic constraints on the incidents of large mammals in Australia, nor is there evidence that large myrmecophages have recently disappeared from our study areas. Evidence for myrmecophages larger than surviving forms occurring in the past is not greater in Australia than in south ern Africa. Fungus-culturing termites (Macrotermitinae) are absent fro m Australia, but are eaten by the largest myrmecophage, the earth-pig, in southern Africa. Fungus-culturing and grass-eating termites are la rger than their nearest counterparts in Australia. In semi-arid sample -sites with grasses and Acacia spp., termites are less abundant in Aus tralia than in southern Africa. Large myrmecophages are associated wit h large leaf-eating eutherian mammals in southern Africa. We suggest t hat food consisting of termites and ants is less productive and reliab le in Australia than in southern Africa. This may be partly because te rmites in Australia lack the relatively rich foods that are continuall y provided to their southern African counterparts by the trampling and dung of grazers and other herbivores and because sporadic but intense fires remove more foliage in Australia than in southern Africa. Our s tudy refutes the role of chance in shaping the Australian fauna, and s hows that different ecological conditions affect the biogeography of m yrmecophages, and termites and ants eaten by them, on the two continen ts. The biotic, and possibly physical, environment is less favourable for large myrmecophages in Australia than in southern Africa.