Course: BIS 105 Environmental Biology

Unit 6 Learning Module

Biodiversity

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 below. 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

"To save every cog and wheel is the first precaution of intelligent tinkering."
- Aldo Leopold, Round River: from the Journals of Aldo Leopold, 1953

What are the “cogs” and “wheels” of life?

Although the concept of biodiversity did not become a vital component of biology and political science until nearly 40 years after Aldo Leopold’s death in 1948, Leopold – often considered the father of modern ecology - would have likely found the term an appropriate description of his “cogs and wheels.” Literally, biodiversity is the many different kinds (diversity) of life (bio-). Biologists, however, always alert to levels of organization, have identified three measures of life’s variation. Species diversity best fits the literal translation: the number of different species in a particular ecosystem or on Earth. A second measure recognizes variation within a species: differences among individuals or populations make up genetic diversity. Finally, as Leopold clearly understood, the “cogs and wheels” include not only life but also the land, sea, and air that support life. Ecosystem diversity describes the many types of functional units formed by living communities interacting with their environments. Although all three levels of diversity are important, the term biodiversity usually refers to species diversity.

A discussion of biodiversity is available at http://youtu.be/0-PE3ve3w2w (7:35).

Species diversity is quantified in two ways, species richness and species evenness. Species richness is the total number of different species in a community. Species evenness identifies the relative abundance of each species. Typically as you move up trophic levels there are fewer individuals than at lower trophic levels. Looking at organisms within a similar trophic level, there should be relatively the same number of individuals in each species. This would mean the community has high species evenness. Alternatively, if one or two species are much more common than the other species, then the community has low species evenness. These less abundant species are at a higher risk of declines or elimination from an environment.

Communities with high species richness and diversity generally have a more elaborate food webs. This can enable greater nutrient cycling and make the community more resilient. Resilience describes the ability for a community to adjust to changes and return to its original state.

Importance of Biodiversity

A place such as a coral reef has many different species of plants and animals. That means the coral reef is a ecosystem with high biodiversity. Similarly, a rainforest is an ecosystem with extreme importance because of its biodiversity. Why is biodiversity so important? In addition to maintaining the health and stability of the ecosystem, the diversity of life provides us with many benefits.

Extinction is a threat to biodiversity. Does it matter if we are losing thousands of species each year? The answer is yes. It matters even if we consider not only the direct benefits to humans, but also the benefits to the ecosystems. The health and survival of ecosystems is related to that ecosystem's biodiversity.

Economic Importance

Economically, there are many direct benefits of biodiversity. As many as 40,000 species of fungi, plants, and animals provide us with many varied types of clothing, shelter, medicines and other products. These include poisons, timber, fibers, fragrances, papers, silks, dyes, adhesives, rubber, resins, skins, furs, and more. According to one survey, 57% of the most important prescription drugs come from nature. Specifically, they come from bacteria, fungi, plants, and animals. But only a small amount of species with the ability to give us medicines have been explored. The loss of any species may mean the loss of new medicines, which will have a direct effect on human health.

Biodiversity and Technology

Nature has inspired many technologies in use today. Biomimicry, also known as biomimetics, uses organisms to inspire technology or engineering projects. By studying animals and their traits, we are able to gain valuable information that we can put to use to help us. For example, rattlesnake heat-sensing pits helped inspire the development of infrared sensors. Zimbabwe’s Eastgate Centre was inspired by the air-conditioning efficiency of a termite mound.

Design of the Eastgate Centre, in Zimbabwe, which requires just 10% of the energy needed for a conventional building of the same size, was inspired by a biological design.

The air-conditioning efficiency of this termite mound was the inspiration for the Eastgate Centre.

Ecological Importance

Biodiversity also has many benefits to ecosystems. High biodiversity makes ecosystems more stable. What can happen to an ecosystem if just one species goes extinct? What if that one species was a producer or decomposer? Maybe the resulting species will adapt. Other species may fill in the niche left by the extinct species. But the extinction of one species could have a "domino" effect, resulting in the extinction of other species. This could greatly effect the stability of the whole ecosystem.

One important role of biodiversity is that it helps keep the nutrients, such as nitrogen, in the soil. For example, a diversity of organisms in the soil allows nitrogen fixation and nutrient recycling to happen. Biodiversity also allows plants to be pollinated by different types of insects. And of course, different species of fungi are necessary to recycle wastes from dead plants and animals. These are just a few of the many examples of how biodiversity is important for ecosystems.