Daily heterothermy in mammals: Coping with unpredictable environments

Zoogeographical patterns of daily heterothermy in mammals show that the Afr otropical and Australasian zones have the highest number of species, genera and orders exhibiting daily torpor. The Palaearctic has the lowest inciden ce of daily torpor. The Australasian and the Afrotropical zones also showed the highest incidences of summer torpor and torpor in desert species. Thes e patterns suggest an association of daily torpor with unpredictable enviro nments (low inclement energetic gains), versus an association of hibernatio n with predictably cold seasons thigh inclement energetic costs).