- Define biodiversity.
- Identify economic benefits and ecosystem services of biodiversity.
- Relate human actions to the sixth mass extinction.
species that is introduced (usually by human actions) into a new habitat where it may lack local predators and out-compete native species
destruction or disruption of Earth’s natural habitats, most often due to human actions such as agriculture, forestry, mining, and urbanization
sixth mass extinction
current mass extinction caused primarily by habitat loss due to human actions
One of the effects of human overpopulation is the loss of other species. The rapidly growing human population has reduced Earth’s 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 in Figure 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.
Known species represent only a fraction of all species that exist on Earth.
A discussion of biodiversity is available at http://www.youtube.com/watch?v=vGxJArebKoc (6:12).
Millions of Unseen Species
A study released in August 2011 estimates that Earth has almost 8.8 million animal, plant and fungi species, but we've only discovered less than a quarter of them. So far, only 1.9 million species have been found. Recent newly discovered species have been very diverse: a psychedelic frogfish, a lizard the size of a dime and even a blind hairy mini-lobster at the bottom of the ocean. There are potential benefits from these undiscovered species, which need to be found before they disappear from the planet. The study estimates that of the 8.8 million species, about 6.5 million would be on land and 2.2 million in the ocean. The research estimates that animals rule with 7.8 million species, followed by fungi with 611,000 and plants with just shy of 300,000 species. See http://news.yahoo.com/wild-world-millions-unseen-species-fill-earth-210051661.html for additional information.
Why Is Biodiversity Important?
Human beings benefit in many ways from biodiversity. Biodiversity has direct economic benefits. It also provides services to entire ecosystems.
Economic Benefits of Biodiversity
The diversity of species provides humans with a wide range of economic benefits:
- Wild plants and animals maintain a valuable pool of genetic variation. This is important because domestic species are genetically uniform. This puts them at great risk of dying out due to disease.
- Other organisms provide humans with many different products. Timber, fibers, adhesives, dyes, and rubber are just a few.
- Certain species may warn us of toxins in the environment. When the peregrine falcon nearly went extinct, for example, it warned us of the dangers of DDT.
- More than half of the most important prescription drugs come from wild species. Only a fraction of species have yet been studied for their medical potential.
- Other living things provide inspiration for engineering and technology. For example, the car design in Figure below was based on a fish.
From flowers to fish, biodiversity benefits humans in many ways.
Ecosystem Services of Biodiversity
Biodiversity generally increases the productivity and stability of ecosystems. It helps ensure that at least some species will survive environmental change. It also provides many other ecosystem services. For example:
- Plants and algae maintain the atmosphere. During photosynthesis, they add oxygen and remove carbon dioxide.
- Plants help prevent soil erosion. They also improve soil quality when they decompose.
- Microorganisms purify water in rivers and lakes. They also return nutrients to the soil.
- Bacteria fix nitrogen and make it available to plants. Other bacteria recycle the nitrogen from organic wastes and remains of dead organisms.
- Insects and birds pollinate flowering plants, including crop plants.
- Natural predators control insect pests. They reduce the need for expensive pesticides, which may harm people and other living things.
Human Actions and the Sixth Mass Extinction
Over 99 percent of all species that ever lived on Earth have gone extinct. Five mass extinctions are recorded in the fossil record. They were caused by major geologic and climatic events. Evidence shows that a sixth mass extinction is occurring now. Unlike previous mass extinctions, the sixth extinction is due to human actions.
Some scientists consider the sixth extinction to have begun with early hominids during the Pleistocene. They are blamed for over-killing big mammals such as mammoths. Since then, human actions have had an ever greater impact on other species. The present rate of extinction is between 100 and 100,000 species per year. In 100 years, we could lose more than half of Earth’s remaining species.
Causes of Extinction
The single biggest cause of extinction today is habitat loss. Agriculture, forestry, mining, and urbanization have disturbed or destroyed more than half of Earth’s land area. In the U.S., for example, more than 99 percent of tall-grass prairies have been lost. Other causes of extinction today include:
Exotic species introduced by humans into new habitats. They may carry disease, prey on native species, and disrupt food webs. Often, they can out-compete native species because they lack local predators. An example is described in Figure below.
- Over-harvesting of fish, trees, and other organisms. This threatens their survival and the survival of species that depend on them.
- Global climate change, largely due to the burning of fossil fuels. This is raising Earth’s air and ocean temperatures. It is also raising sea levels. These changes threaten many species.
- Pollution, which adds chemicals, heat, and noise to the environment beyond its capacity to absorb them. This causes widespread harm to organisms.
- Human overpopulation, which is crowding out other species. It also makes all the other causes of extinction worse.
Brown Tree Snake. The brown tree snake is an exotic species that has caused many extinctions on Pacific islands such as Guam.
Effects of Extinction
The results of a study released in the summer of 2011 have shown that the decline in the numbers of large predators like sharks, lions and wolves is disrupting Earth's ecosystem in all kinds of unusual ways. The study, conducted by scientists from 22 different institutions in six countries, confirmed the sixth mass extinction. The study states that this mass extinction differs from previous ones because it is entirely driven by human activity through changes in land use, climate, pollution, hunting, fishing and poaching. The effects of the loss of these large predators can be seen in the oceans and on land.
- Fewer cougars in the western US state of Utah led to an explosion of the deer population. The deer ate more vegetation, which altered the path of local streams and lowered overall biodiversity.
- In Africa, where lions and leopard are being lost to poachers, there is a surge in the numbers of olive baboons who are transferring intestinal parasites to human who live nearby.
- In the oceans, industrial whaling led a change in the diets of killer whales, who eat more sea lion, seals and otters and dramatically lowered those population counts.
The study concludes that the loss of big predators has likely driven many of the pandemics, population collapses and ecosystem shifts the Earth has seen in recent centuries. See http://news.yahoo.com/loss-big-predators-disrupts-earth-ecosystem-study-181200945.html for additional information.
KQED: Disappearing Frogs
Around the world, frogs are declining at an alarming rate due to threats like pollution, disease and climate change. Frogs bridge the gap between water and land habitats, making them the first indicators of ecosystem changes. Meet the California researchers working to protect frogs across the state and across the world at http://www.kqed.org/quest/television/disappearing-frogs. Learn about the plight of the yellow-legged frog at http://www.kqed.org/quest/radio/plight-of-the-yellowlegged-frog.
KQED: Nonnative Species
Scoop a handful of critters out of the San Francisco Bay and you'll find many organisms from far away shores. Invasive kinds of mussels, fish and more are choking out native species, challenging experts around the state to change the human behavior that brings them here. See http://www.kqed.org/quest/television/san-francisco-bay-invaders for more information.
How You Can Help Protect Biodiversity
There are many steps you can take to help protect biodiversity. For example:
- Consume wisely. Reduce your consumption wherever possible. Re-use or recycle rather than throw out and buy new. When you do buy new, choose products that are energy efficient and durable.
- Avoid plastics. Plastics are made from petroleum and produce toxic waste.
- Go organic. Organically grown food is better for your health. It also protects the environment from pesticides and excessive nutrients in fertilizers.
- Save energy. Unplug electronic equipment and turn off lights when not in use. Take mass transit instead of driving.
See http://www.youtube.com/watch?v=GnK7gNXxb3c for an outstanding 60 Minutes video of the Great Migration in Kenya, and the issues facing these animals.
KQED: Lost Salmon
Because of a sharp decline in their numbers, the entire salmon fishing season in the ocean off California and Oregon was canceled in both 2008 and 2009. At no other time in history has this salmon fishery been closed. The species in the most danger is the California coho salmon. Examine efforts to protect the coho in Northern California and explores the important role salmon play in the native ecosystem at http://www.kqed.org/quest/television/californias-lost-salmon and http://www.kqed.org/quest/television/coho-salmon-in-muir-woods.
The Encyclopedia of Life
The Encyclopedia of Life (EOL) is a free, online collaborative encyclopedia intended to document all of the 1.9+ million living species known to science. It is compiled from existing scientific databases, and from contributions by experts and non-experts world-wide. Its goal is to build one infinitely expandable page for each species, including videos, sound, images, graphics, and text. As the discovery of new species is expected to continue (the current rate is about 20,000 new species identified per year), EOL will grow continuously. As taxonomy finds new ways to include species identified by molecular techniques, the rate of new species additions will increase - in particular with respect to the microbial world of (eu)bacteria, archaebacteria and viruses. EOL went live on February 26, 2008 with 30,000 entries.
The EOL has developed web-based tools and services that provide visitors enhanced capability to use EOL content for their own purposes and to contribute to the site and become part of a growing international community interested in biodiversity.
See http://www.eol.org/ and http://www.youtube.com/watch?v=6NwfGA4cxJQ for additional information.
In addition, Understanding Biodiversity, the CK-12 and EOL biodiversity-themed resource currently under development, is an expanding library of biodiversity information aimed at the secondary-level biology classroom. Understanding Biodiversity pages will provide information for each species relevant to the high school biology curriculum: cell biology, genetics, evolution, ecology, and physiology. If you would like to submit a species page to Understanding Biodiversity, email a proposal for contributions to firstname.lastname@example.org.
Field Guides pull selected content from EOL species pages into a format that is easier to view and use for particular projects. Rather than sorting through all 1.9 million species pages and all of the Table of Contents information, users will see information for just the organisms and information they select. Users are able to customize and edit the content in their field guide.
You can try creating a field guide for the organisms found in your schoolyard or for the organisms discussed in another chapter of this FlexBook. See what information is found in EOL and what is missing. Is there anything you can contribute to EOL, such as an image or class research information?
Lend an ear and discover the wonders of nature—right outside your back door and halfway around the world. EOL audio broadcasts are aimed at learning about life-from organisms as small as yeast to as big as a bowhead whale. Hear people's stories about nature and hone your backyard observation skills. Explore the diversity of life—five minutes and One Species at a Time. Listen to the podcasts online, or download them and take them with you on your own exploration of the world around you.
One Species at a Time
The audio series One Species at a Time is a tribute to life on Earth http://education.eol.org/podcast/one-species-time. Each episode is a story, a mystery, a riddle, or an exploration of a different creature pulsing, fluttering, surging, respiring, and galloping on this planet. Biodiversity is center stage, from scurrying invasive beetles in Oregon to the threatened cedar trees of Lebanon to Ediacaran fauna from 580 million years ago. There are associated Extras and a Meet the Scientist section with each podcast. Some have associated educational materials. Some have associated educational materials. All podcasts are freely available and can be used in other projects.
The Biodiversity Heritage Library
Twelve major natural history museum libraries, botanical libraries, and research institutions have joined to form the Biodiversity Heritage Library. The participating libraries have over two million volumes of biodiversity literature collected over 200 years to support the work of scientists, researchers, and students in their home institutions and throughout the world.
The Biodiversity Heritage Library (BHL) consortium cooperates to digitize and make accessible the biodiversity literature held in their collections and to make that literature available for open access and responsible use as a part of a global “biodiversity commons.” Because of the BHL's success in digitizing a significant mass of biodiversity literature, the scientific documentation of the study of living organisms since the time of Linnaeus has became easily accessible.
Anyone can access the BHL website directly or link to it from any EOL species page. When on a species page, scroll down through the Table of Contents on the left hand side of the page to the "References and More Information" section and click on "Biodiversity Heritage Library." BHL literature directly related to the species under consideration will be shown.
The published literature on biological diversity has limited global distribution; much of it is available in only a few select libraries in the developed world. These collections are of exceptional value because the domain of systematic biology depends - more than any other science - upon historic literature. Yet, this wealth of knowledge is available only to those few who can gain direct access to significant library collections. Literature about the life that exists in developing countries is often not available within their borders. Biologists have long considered that access to the published literature is one of the chief impediments to the efficiency of research in the field. Among other results, free global access to digitized versions of the literature would make available information about the Earth’s species to all parts of the world. Many of the texts digitized by the BHL have until now only been held in a few European or North American libraries. Now, with this resource, scientists and student in the developing world have access to them, thereby accelerating biodiversity research.
Since 2009, the BHL has expanded globally. The European Commission’s eContentPlus program has recently funded the BHL-Europe project, with 28 institutions, to assemble the European language literature. Additionally, the Chinese Academy of Sciences, the Atlas of Living Australia, Brazil, and the Bibliotheca Alexandrina have created regional BHL sites. These projects will work together to share content, protocols, services, and digital preservation practices.
- Biodiversity refers to the number of species in an ecosystem or the biosphere as a whole.
- Biodiversity has direct economic benefits. It also provides services to entire ecosystems.
- Evidence shows that a sixth mass extinction is occurring. The single biggest cause is habitat loss caused by human actions. There are many steps you can take to help protect biodiversity. For example, you can use less energy.
- The Encyclopedia of Life is a free, online collaborative encyclopedia intended to document all of the 1.9+ million living species known to science.
Lesson Review Questions
1. What is biodiversity?
2. List three economic benefits of biodiversity.
3. Identify ecosystem services of biodiversity.
4. How is human overpopulation related to the sixth mass extinction?
5. Create a poster that conveys simple tips for protecting biodiversity.
6. Why might the brown tree snake or the peregrine falcon serve as “poster species” for causes of the sixth mass extinction?
7. Predict what would happen to other organisms in an ecosystem in which all the decomposers went extinct?
8. Describe a hypothetical example showing how rising sea levels due to global warming might cause extinction.
Points to Consider
All species depend on the environment to provide them with the resources they need. As populations grow, resources may be used up. Just using the resources can create more problems.
- What resources do you depend on?
- Does using the resources pollute the environment? Are the resources running out?