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Monday, 23 January 2017

Ecology and Biogeography

Ecology and biogeography In 1870, the German biologist Ernst Haeckel (1834-1919) first coined the term 'ecology' and defined it as 'the total relations of the animal both to its inorganic and organic environment'. In some ways that encapsulated what ecology is today; the study of the interactions between organisms and their environment; but also including (1) the study of the abundance of organisms in space and time and (2) the processes in biological communities. Early in the 20th century, ecology emerged from natural history and wildlife manage-ment as a science. 

Developments in early ecology occurred simultaneously in both North America and Europe. Landmarks in early animal ecology text-books included Arthur Pearse's Animal Ecology (published by McGraw-Hill in 1926) and the work of Charles Elton (Animal Ecology, published by Sidgwick & Jackson in 1927). 

Much of the stimulus for the emergence of plant community studies came from the work of Tansley (1935) and Watt (1947) in Britain and from F. E. Clements in North America (Dynamics of Vegetation, published by Hafner Press in 1949). The establishment of the British Ecological Society in 1913 and the Ecological Society of America, founded in 1916, provided a professional basis for ecology. 

Ecology has become a well-known word but sadly the discipline of ecology is not well understood and is even equated with environmentalism and being 'green'. That is another topic which cannot be discussed here. As the science of ecology (objective, quantifiable, experimental) began to emerge early this century it was, not surprisingly, going to have close links with biogeography  not surprising because both ecologists and geographers were interested in the patterns of distribution of organisms in space and in time and the processes which determined those patterns. As early as 1924, Richard Hesse in his Tiergeographie auf Oekologischer Grundlage wrote about `ecological animal geography' as a young science. When this work was later translated and published in 1937 it made a marked impact on ecological and biogeographical studies in both Europe and North America. Later academics such as the Americans Robert McArthur and Edward Wilson wrote as if there were no real difference between biogeography and ecology. 

The term 'ecological biogeography' has since been widely used. Although the distribution of organisms and the factors and processes causing those distributions is central to the study of biogeography, ecology is concerned mainly with interactions between organisms and their environ-ment, patterns and processes in ecosystems, as well as with the distribution and abundance. But the study of distribution could also be considered to be a 5 part of the study of abundance; factors affecting distribution will also affect abundance. Studies of distribution and abundance can be undertaken at different levels of organisation, including populations, species and biological communities. Previously, community-based ecological studies were promi-nent in Europe and North America in the early part of the 20th century. Then in the 1950s came the publication of a particularly important contribution to the scientific study of distribution and abundance. This was a book called The Distribution and Abundance of Animals by two Australian biologists, H. G. Andrewartha and L. C. Birch (1954). 

Rather than studying biological com-munities, these authors had established a strong statistical and analytical approach to population ecology involving three aspects: (1) physiology and behaviour of animals; (2) physiography, climate, soil and vegetation; (3) numbers of individuals in populations. Andrewartha & Birch stressed the spatial relations between 'local popula-tions'. Also, in theprevious work of early ecologists such as Watt (1947), there was reference to shifting mosaics of populations; that is, species found on natural) occurring patchy and transient habitats. These references to y  population processes have more recently found their way into the literature dealing with the theory of metapopulations . 

 Later, we give examples of how biogeographical information can be ana-lysed . In addition to examples of analysis we also describe some theories and models that have been used in biogeographical studies. But why theories and what is a model? In biogeography, theories (that is sets of ideas to try to explain or test something) are used to try to understand processes (for example, the processes which determine the number of species on an island). Models are theories that can he tested to some extent and therefore may be used to predict the effects of certain impacts on the natural world (for example, climate change on the distribution of biological communities). 

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