Evolution in Steppe with Few Large, Hooved Mammals

摘要: Communities are organized through both the proximate and evolutionary constraints that shape structure of populations interaction among species. Proximate can be manipulated experimentally to assess relative influence a component species on overall community, as in analyses keystone (Paine 1969) or dominant These instructive detecting how current selection pressures populations. Responses interspecific interactions, however, not made an vacuum, but rather reflect history prior have molded species' traits. Overall some communities turn may influenced large extent by few traits evolving most abundant response continuous strong pressure. Assessment effect these particular suites community organization is difficult experimental basis it necessitates removal within than themselves (e.g., Windle Franz 1979). Grasses with their basal intercalary meristems cited commonly having evolved herbivorous mammals (Osborn 1910; Love 1959; Barnard Frankel 1964). Yet temperate grasslands specifically steppes differ greatly habitation throughout Neogene hence plants which they adapted mammalian grazers. In this paper we consider either side Rocky Mountains attempt understand differences acquisition mammal-selected interactions grazers grassland structure. GRASSLANDS AND NATIVE LARGE HERBIVORES IN WESTERN NORTH AMERICA