Biodiversity PDF

# LESSON 1 ## BIODIVERSITY ### FOCUS QUESTION Why is biodiversity important? ### What is Biodiversity? The loss of an entire species in a food web is not an imaginary situation. Entire species permanently disappear from the biosphere when the last member of the species dies in a process called ext...

# LESSON 1 ## BIODIVERSITY ### FOCUS QUESTION Why is biodiversity important? ### What is Biodiversity? The loss of an entire species in a food web is not an imaginary situation. Entire species permanently disappear from the biosphere when the last member of the species dies in a process called extinction. As species become extinct, the variety of species in the biosphere decreases, which decreases the health of the biosphere. Biodiversity is the variety of life in an area that is determined by the number of different species in that area. It is increased by the formation of new species and decreased by the loss of species (extinction). Biodiversity increases the stability of an ecosystem and contributes to the health of the biosphere. There are three types of biodiversity to consider: genetic diversity, species diversity, and ecosystem diversity. ### Genetic diversity The variety of genes or inheritable characteristics that are present in a population comprises its genetic diversity. Figure 1 shows characteristics that are shared by Asian ladybird beetles, such as general body structure. Figure 1 These Asian ladybird beetles, Harmonia axyridis, demonstrate some visible genetic diversity because of their different colors. Suggest some other characteristics that might vary among the beetles. ### Species diversity The number of different species and the relative abundance of each species in a biological community is called species diversity. As you look at Figure 2, notice how many different species of organisms are in this one area. This habitat represents an area with a high level of species diversity because there are many species present in one location. Species diversity, however, is not evenly distributed over the biosphere. As you move geographically from the polar regions to the equator, species diversity increases. For example, Figure 3 on the next page shows the number of bird species from Alaska to Central America. Use the color key to see how diversity changes as you move toward the equator. ### Ecosystem diversity The variety of ecosystems present in the biosphere is called ecosystem diversity. An ecosystem is made up of interacting populations and the abiotic factors that support them. The interactions of organisms affect the development of stable ecosystems. Different locations around the world have different abiotic factors that support different types of life. For example, an ecosystem in Alaska has a set of abiotic factors that supports puffins, which are shown in Figure 4. An ecosystem in South America has a different set of abiotic factors that supports the tropical plant life shown in Figure 4. Like these ecosystems, most of the ecosystems on Earth support a diverse collection of organisms. ### The Importance of Biodiversity Sustaining biodiversity so that ecosystem functioning and productivity are maintained is essential to supporting and enhancing life on Earth. Humans depend on the living world for resources and other benefits provided by diversity. There are economic, aesthetic, and scientific reasons for preserving biodiversity. #### Direct economic value Maintaining biodiversity has a direct economic value to humans. Humans depend on plants and animals to provide food, clothing, energy, medicine, and shelter. Preserving species that are used directly is important, but it also is important to preserve the genetic diversity in species that are not used directly. Those species serve as possible sources of desirable genes that might be needed in the future. The reason there might be a future need for desirable genes is that most of the world's food crops come from just a few species. These plants have relatively little genetic diversity and share the same problems that all species share when genetic diversity is limited, such as lacking resistance to disease. In many cases, close relatives of crop species still grow wild in their native habitat. These wild species serve as reservoirs of desirable genetic traits that might be needed to improve domestic crop species. The distant relative of corn, teosinte, shown in Figure 5, is resistant to the viral diseases that damage commercial corn crops. Using this wild species, plant pathologists developed disease-resistant corn varieties. If this wild species had not been available, this genetic diversity would have been lost, and the ability to develop disease-resistant corn varieties would also have been lost. In addition, biologists are able to transfer genes that control inherited characteristics from one species to the other. This process is sometimes referred to as genetic engineering. Crops have been produced that are resistant to some insects, that have increased nutritional value, and that are more resistant to spoilage. Most wild species of plants and animals have not been evaluated for useful genetic traits. The opportunity to benefit from these genes is lost forever if wild species of plants and animals become extinct. This increases the importance of species that currently have no perceived economic value because their economic value might increase in the future. #### Indirect economic value A healthy biosphere provides many services to humans and other organisms that live on Earth. For example, green plants provide oxygen to the atmosphere and remove carbon dioxide. Natural processes provide drinking water that is safe for human use. Substances are cycled through living organisms and nonliving processes, providing nutrients for all living organisms. As you will soon learn, healthy ecosystems provide protection against floods and drought, generate and preserve fertile soils, detoxify and decompose wastes, and regulate local climates. ### Aesthetic and scientific values Biodiversity and healthy ecosystems have aesthetic and scientific values. Sustaining biodiversity helps humanity by preserving landscapes of recreational or inspirational value, such as the ecosystem shown in Figure 8. #### Check Your Progress - Biodiversity is important to the health of the biosphere - There are three types of biodiversity: genetic, species, and ecosystem - Biodiversity has aesthetic and scientific values, and direct and indirect economic value. - It is important to maintain biodiversity to preserve the reservoir of genes that might be needed in the future. - Healthy ecosystems can provide some services at a lesser expense than the use of technology. **Demonstrate Understanding** 1. Explain why sustaining biodiversity is essential to supporting and enhancing life on Earth. 2. Explain how extinction affects biodiversity. 3. Generalize why maintaining biodiversity has a direct economic value to humans. 4. Differentiate between the direct and indirect economic value of biodiversity. 5. Evaluate and discuss the importance of maintaining biodiversity for future medical needs. **Explain Your Thinking** 6. Design a course of action for the development of a building project in your community, such as a housing development, city park, or highway, that provides for the maintenance of biodiversity in the plan. 7. **WRITING CONNECTION** Write an argument that describes the importance of maintaining genetic diversity in domesticated animals, such as dogs, cats, pigs, cattle, and chickens. Include the advantages and disadvantages in your report.