Learning Outcomes
Biological diversity is the variety of life on earth. This includes all the different plants, animals, and microorganisms; the genes they contain; and the ecosystems they form on land and in water. Biological diversity is constantly changing. It is increased by new genetic variation and reduced by extinction and habitat degradation. What Is Biodiversity?Biodiversity refers to the variety of life and its processes, including the variety of living organisms, the genetic differences among them, and the communities and ecosystems in which they occur. Scientists have identified about 1.9 million species alive today. They are divided into the six kingdoms of life shown in Figure 2. Scientists are still discovering new species. Thus, they do not know for sure how many species really exist today. Most estimates range from 5 to 30 million species. Cogs and Wheels
Leopold—often considered the father of modern ecology—would have likely found the term biodiversity an appropriate description of his “cogs and wheels,” even though the idea did not become a vital component of biology until nearly 40 years after his death in 1948. Literally, the word biodiversity means the many different kinds (diversity) of life (bio-), or the number of species in a particular area. Biologists, however, are always alert to levels of organization, and have identified three unique measures of life’s variation:
Although all three levels of diversity are important, the term biodiversity usually refers to species diversity! Biodiversity provides us with all of our food. It also provides for many medicines and industrial products, and it has great potential for developing new and improved products for the future. Perhaps most importantly, biological diversity provides and maintains a wide array of ecological “services.” These include provision of clean air and water, soil, food and shelter. The quality—and the continuation— of our life and our economy is dependent on these “services.”
The long isolation of Australia over much of the last 50 million years and its northward movement have led to the evolution of a distinct biota. Significant features of Australia’s biological diversity include:
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