Biogeography: the nature of the subject, its history and its applications
In 1994, an article in the journal New Scientist proclaimed that 'Since biogeography holds the key to the survival of life, it deserves more attention' (Bowman, 1994). That statement is a very fitting opening to this first chapter. Biogeography is about the geography of plants, animals and other or-ganisms, that is, the study of the geographical distribution of plants, animals and other organisms.
Biogeographical research helps us to understand the patterns and processes of distribution and the factors that cause and maintain those patterns and processes. The patterns of distribution that we find today amongst living organisms have been determined by many things, including the following: Evolution Physiological and behavioural adaptations Dispersal mechanisms and levels of dispersal abilities Competition between species Ecological succession Climate change Sea level changes Moving continents through a process called plate tectonics Direct and indirect impact of humans The distribution and abundance of plants (phytogeography) and animals (zoogeography) have been the two main divisions of biogeography. Both those divisions embrace elements of several disciplines including biology, geography, taxonomy, geology, climatology and ecology. Many biologists, taxonomists, geologists, climatologists and ecologists have interests in various aspects of biogeography and indeed some have particular views as to the precise nature of biogeography.
Those differences in views are based partly on differences of scale, be it in time or spatially. For example, a geologist's view might be particularly biased by an interest in evolutionary processes over very long periods of time (millions of years) perhaps in relation to plate tectonics. Geographers might take a special interest in researching the distribution of plants and animals over the last few thousand years, perhaps in relation to the post-glacial periods. An ecologist's view of biogeography might be dominated by those factors which determine and maintain the distribution of plants and animals within certain localities and over much shorter periods of time (perhaps in relation to the reduction and fragmentation of habitats in the last few decades). These different views contribute to the rich and varied nature of biogeographical research and its many important, practical applications. The common theme in all approaches to the study of biogeography is the study of the geographical distribution of groups of plants, animals and other organ-isms from a spatial or space perspective (that is, over land, in the soil, in water and in the air) and a temporal or time perspective (that is changes in distribution that occur over time). Biogeography provides a valuable link between traditional single disciplines (such as ecology, taxonomy and conser-vation biology) and a focus for interdisciplinary studies. That is important because many if not all environmental problems facing us today require an interdisciplinary approach (that is an integration of several disciplines, in-cluding ecology, geology, economics, policy and sociocultural factors). Biogeography is more than about mapping the geographical distribution of organisms (present and past) at different spatial scales or merely dividing the land and sea into regions which are based on groups of characteristic or-ganisms.
Once a predominantly descriptive discipline, biogeography is now a quantitative science. It has applications in conservation, helping to establish a strategy for the location, extent and management of protected areas. It has applications in trying to achieve sustainable use of living resources and in environmental assessment by helping to ensure the least impact on the natural environment. It has applications in helping to tackle many aspects of environ-mental change, whether it be modelling the effects of changing weather patterns on agriculture or those of introduced and invasive species on native (indigenous) commercial fish species.
Before we can look in more detail at biogeography we need to know what we are dealing with and thus a brief introduction to the classification of organisms is helpful. We then go on to introduce the subject of biogeography and the