Ecological biogeography: examines how relationships between organisms and environment help determine when and where organisms are found , range. Geographical area within which a given species can be found. Range determinants: moisture and temperature (climate) are generally the most important physical variables determining species range, but other variables also important. Interspecific interactions include competition, facilitation, herbivory/predation: temperature. Influences physiological processes, in turn affects tissue generation (eg photosynthesis, respiration) Extreme temperatures can damage organisms (eg low freezing tolerance: precipitation. Different species adapted to different moisture regimes. The functional role plated by an organism as well as the physical space it inhabits (its occupation and address : fundamental niche. The total range of conditions under which a species can survive. Potential distribution of the species in the absence of competition with other species. Hypothetical, in a perfect world: realizes niche. The conditions under which an organism actually exists succession. Actual distribution of the species in the presence of competition with other species.