Endemic species and subspecies occupy a defined and limited area, usually referring to a single country or biome, such as Giant Sable of central Angola and Welwitschia mirabilis of the Namib Desert.
These individual populations form part of what is referred to as a metapopulation (Sect. A species might comprise many, often isolated, populations. Populations vary in terms of the area encompassing all the individuals of the species, representing their geographic range. The impact of invasive species on rural livelihoods is used to demonstrate the fragility of natural communities to anthropogenic disturbance.Ī population is a group of individuals of the same species that inhabit a given area. At landscape scales, interactions within and between populations and communities of existing and immigrant species, and the rates of immigration and extinction, are explored using the theories of island biogeography and of metapopulations. To these are added interactions between two species with reciprocal effects-predation, parasitism, mutualism and commensalism. Interactions between consumers and their food source provides a basis for their classification into herbivores, carnivores, omnivores and decomposers. The use of models of life history patterns (such as r- and K-strategies), and of the concepts of the ecological niche and guild are explained.
Measures of species richness, evenness, diversity, endemism and categories of threat are important to conservation needs assessment and are illustrated with examples from Africa. The processes of evolution by natural selection, genetic differentiation and speciation are described. This Chapter details the hierarchy of ecological assembly, from organismic, to population, to community, to ecosystem and to landscape levels.
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