1. Biodiversity
Read the lesson title aloud to students.

2. Learning Objectives Define biodiversity and explain its value.
Identify current threats to biodiversity.
Describe how biodiversity can be preserved.
Click to reveal each of the learning objectives.
To engage students in this lesson and build a background for them, show students photos of ivory products. Explain that the main source of ivory is elephant tusks. Point out that there are laws against killing elephants to take their tusks and trade in ivory products has been banned by international law, but a market for ivory still exists.
Ask students to predict how this demand for ivory affects elephant populations and the biosphere.
Distribute the worksheet for this lesson and tell students to use it to create a vocabulary word map for the primary vocabulary term in this lesson: biodiversity.
Make sure students understand that at the end of the presentation, they should be able to define biodiversity and explain its value, identify current threats to biodiversity, and describe how biodiversity can be preserved.

3. The Value of Biodiversity
The total of all genetically based variation in all organisms in the biosphere
Types of biodiversity:
ecosystem diversity
species diversity
genetic diversity
Explain to students that biological diversity, or biodiversity, is the total of all genetically based variation in all organisms in the biosphere.
Tell students that biodiversity can be described on three levels: ecosystem diversity, species diversity, and genetic diversity.
Click to reveal “ecosystem diversity.”
Explain that ecosystem diversity refers to the variety of habitats, communities, and ecological processes in the biosphere.
Click to reveal “species diversity.”
Tell students that the number of different species in the biosphere or in a particular area is called species diversity. To date, biologists have identified and named more than 1.2 million eukaryotic species, and they estimate that 8.7 million more are yet be discovered.
Animals with backbones are among the best-known organisms, yet new species, like the snake shown, are constantly being identified. Point out to students that this tiny snake, native to the island of Barbados, is one of many recently discovered species.
Also point out to students that much more diversity exists among single-celled organisms.
Ask: Why are you more likely to discover a new vertebrate species in a tropical area than in a desert?
Answer: There is much greater species diversity in a tropical area than in a desert. Ecosystem diversity is also greater in a tropical area.
Click to reveal “genetic diversity.”
Explain that genetic diversity refers to all the different forms of genetic information carried by a particular species, or by all organisms. Within each species, genetic diversity refers to the total of all different forms of genes present in that species. Genetic diversity by itself can be invisible. Yet this vital kind of diversity is responsible for within-species variations among organisms, both in individual ecosystems and among different ecosystems.
State that genetic diversity is the raw material that enables organisms to adapt to changing external factors.

4. Valuing Biodiversity Contributes to medicine and agriculture
Maintains ecosystem goods and services
Enables organisms and ecosystems to adapt
Tell students that although many people don’t think of biodiversity as a natural resource, it is one of Earth’s greatest treasures.
Ask: Why is biodiversity important?
Answer: Biodiversity’s benefits include offering invaluable contributions to medicine and agriculture, maintaining ecosystem goods and services, and enabling organisms and ecosystems to adapt to environmental change.
As a class, discuss the value of biodiversity, including the types of biodiversity and biodiversity’s benefits to society. Make sure students understand that biodiversity exists on three levels: ecosystem diversity, species diversity, and genetic diversity.
Ask: If an ecologist were to describe the number and variety of habitats in a biome, what level of biodiversity would he or she be referring to?
Answer: ecosystem diversity

5. Biodiversity and Medicine
Many medicines were first discovered in wild species.
information carried by diverse species is like a “natural library.”
Genetic
Explain to students that many medicines, including painkillers like aspirin and antibiotics like penicillin, were first discovered in wild species. Compounds discovered in wild species are also used to treat diseases like depression and cancer.
Point out that the foxglove, shown in the picture, contains compounds called digitalins that are used to treat heart disease. These compounds are assembled according to instructions coded in genes carried by species in nature.
Ask a volunteer to fill in the missing word in the statement.
Click to reveal the answer.
Tell students: Genetic information carried by diverse species is like a “natural library” from which we have much to learn.
Ask: What do you think is one way the loss of biodiversity adversely affects humans?
Answer: The loss of biodiversity would limit the medicines that could be developed.

6. Biodiversity and Agriculture
Genetic diversity is important in agriculture.
Wild plants may carry useful genes.
Explain to students that genetic diversity is also important in agriculture.
Most crop plants have wild relatives, like the potatoes shown. These wild plants may carry genes we can use—through plant breeding or genetic engineering—to transfer disease resistance, pest resistance, or other useful traits to crop plants.
Ask: What could happen that would cause farmers to turn to a wild relative of a crop plant?
Answer: A devastating disease could spread through a crop. If a wild relative were resistant to the disease, then farmers could turn to those plants to replace or modify the crop plants.
Tell students that the genetic diversity of wild potatoes in South America can be seen in the colorful varieties shown in this picture. Explain that the International Potato Center, based in Peru, houses a “library” of more than 4,500 tuber varieties.

7. Biodiversity and Ecosystems
Biodiversity can influence an ecosystem’s:
stability
productivity
value to humans
Tell students: The number and variety of species in an ecosystem can influence that ecosystem.
Click to reveal the ways biodiversity can influence the ecosystem.
Explain that biodiversity influences an ecosystem’s stability, productivity, and value to humans.
Click to reveal a statement about keystone species.
Ask for a volunteer to complete the sentence.
Click to reveal the correct answer.
Tell students: Sometimes the presence or absence of a single keystone species, like the sea otter shown, can completely change an ecosystem.
Explain that the sea otter is a keystone species. When the otter population falls, the population of its favorite prey, sea urchins, goes up. Population increases in sea urchins, in turn, cause a dramatic decrease in the population of sea kelp, the sea urchin’s favorite food.
Ask: What might be the impact of a decrease in sea kelp?
Answer: There might be a decrease in the number of fish that thrive in kelp forests and a decrease in the animals that eat those fish.
Point out that healthy and diverse ecosystems play a vital role in maintaining soil, water, and air quality.
Explain that genetic diversity within species provides variations that can make it possible for populations to change over time as their environments change.
The presence or absence of a single can completely change an ecosystem.
keystone species

8. Threats to Biodiversity
Altered habitats
Hunting
Invasive species
Pollution in food webs
Climate change
Parks
Area
Explain to students that scientists estimate that more than 99 percent of the species that have ever lived are now extinct. So extinction is not new. But human activity today is causing the greatest wave of extinctions since dinosaurs disappeared.
Ask: What are the most significant threats to biodiversity?
Answer: Humans reduce biodiversity by altering habitats, hunting, introducing invasive species, releasing pollution into food webs, and contributing to climate change.
Explain that when natural habitats are eliminated for agriculture or development, species in those habitats become extinct. But habitats don’t need to be completely destroyed to put species at risk. Development often splits ecosystems into pieces, a process called habitat fragmentation, leaving habitat “islands.”
Click to reveal the picture of a biological island.
Tell students: A biological island can be any patch of habitat surrounded by a different habitat, as shown in this picture.
Explain that deforestation for housing developments in Florida has led to the pattern of forest “islands” shown here.
Tell students: The smaller a habitat island is, the smaller the number of species that can live there and the smaller the populations of those species the island can support. Both these kinds of environmental changes impact ecosystem stability by increasing vulnerability to other kinds of disturbance.
Click to reveal an area for completing the following activity.
Call on volunteers to name parks or other natural areas in your community.
Make a list of these in the space provided.
Then, have students estimate the size of each area on the list (or look up the areas ahead of time or, if possible, have students look up the area of each).
Add the areas of all the parks together and circle the sum.
Ask: What difference would it make to the area’s biodiversity if there were one natural area equal in size to the sum of all the existing natural areas?
Answer: There would be greater biodiversity in the one big area, with more genetic diversity and likely more species diversity.

9. Hunting and Wildlife Product Demand
Meat
Commercial value
Body parts
Sale as pets
Explain that humans can push species to extinction by hunting. Many animals are hunted for meat; for their commercially valuable hides, skins, or feathers; or for body parts believed to have medicinal properties. Still others, like the parrots shown, are hunted to be sold as pets.
Point out that aggressive hunting led to the extinction of the Carolina parakeet and the passenger pigeon in the early 1900s. Today, endangered species in the United States are protected from hunting, but hunting still threatens rare animals in Africa, South America, and Southeast Asia.
Tell students: Hunted species are affected even more than other species by habitat fragmentation because fragmentation increases access for hunters and limits available hiding spaces for prey. Explain that the Convention on International Trade in Endangered Species (CITES) bans international trade in products from a list of endangered species. Unfortunately, it’s difficult to enforce laws in remote wilderness areas.
Ask: What impact do you think hunting has on the animals left behind?
Answer: There are fewer individuals of the species left to reproduce, and therefore hunting decreases the genetic diversity of the species and lessens its chances of surviving ecological disturbances.

10. Introduced Species, Pollution, Climates
Organisms introduced to new habitats can become invasive.
Many pollutants threaten biodiversity.
Climate change is a threat to:
Explain to students that organisms introduced to new habitats can become invasive and threaten biodiversity.
Tell students: Ecologists estimate that there are roughly 4,300 invasive species across the United States. Invasive species can cause harmful changes in ecosystems, driving native species to extinction. One European weed, leafy spurge, infests millions of hectares across the northern Great Plains. On rangelands, leafy spurge displaces grasses and other food plants, and its milky latex can sicken or kill cattle and horses.
Each year, ranchers and farmers in the Dakotas, Montana, and Wyoming alone suffer losses of more than $144 million because of this single pest.
Explain to students that many pollutants threaten biodiversity. DDT, for example, prevents birds from laying healthy eggs. In the United States, brown pelican, peregrine falcon, and other bird populations plummeted with widespread use of this insecticide.
Tell students: The picture shows pollutants in the air that have reached an obviously dangerous level.
Point out that acid rain places stress on land and water organisms. Increased carbon dioxide in the atmosphere is dissolving in oceans, making them more acidic and threatening biodiversity on coral reefs and in other marine ecosystems.
Ask: Why is acidic water harmful to coral?
Answer: Corals, most of which have a “skeleton” of calcium carbonate, have evolved to thrive at a certain water pH. Acid rain makes the water more acidic, which can dissolve coral.
Click to reveal the beginning of a statement.
Ask for volunteers to apply what they have learned and fill in the blanks.
Click to reveal the correct answers.
Note that the answers can be in any order.
Tell students: Climate change is a major threat to biodiversity that can impact ecosystem stability.
Remind students that organisms have specific tolerance ranges to temperature and other abiotic external factors. If conditions change beyond an organism’s tolerance, the organism must move to a more suitable location or face extinction.
Ask: Why would a species in a fragmented habitat be vulnerable to climate change?
Answer: Species in fragmented habitats are particularly vulnerable to climate change because if conditions change, they may not be able to move easily to a suitable habitat.
Tell students that estimates vary regarding the effects of climate change on biodiversity. If global temperatures increase 1.5°C–2.5°C over late twentieth-century temperatures, 30 percent of species studied are likely to face increased risk of extinction. If the global temperature increase goes beyond 3.5°C, it is likely that 40–70 percent of species studied will face extinction.
biodiversity
ecosystem stability

11. Conserving Biodiversity
Conserving biodiversity includes:
Protecting individual species
Preserving habitats and ecosystems
Enabling human neighbors to benefit from conservation
Ask: How do we preserve biodiversity?
Answer: Conserving biodiversity includes protecting individual species, preserving habitats and ecosystems, and making certain that human neighbors of protected areas benefit from participating in conservation efforts.
Talk about the strategies for conserving biodiversity. Make sure students understand why these are important.
Ask: How does a national park such as Yellowstone National Park help conserve biodiversity?
Answer: It conserves biodiversity by preserving habitats and ecosystems.
Ask: Why do you think human interests must be taken into account in conservation efforts?
Answer: If human interests are taken into account, populations around the world are more likely to support conservation efforts.

12. Protecting Individual Species
The Association of Zoos and Aquariums (AZA) oversees plans to protect roughly 200 threatened and endangered species.
Explain that in the past, most conservation efforts focused on individual species, and this work continues today.
The Association of Zoos and Aquariums (AZA) oversees plans to protect roughly 200 threatened and endangered species, including the giant pandas shown in this picture. The AZA carefully selects and manages mating pairs of captive animals to maximize genetic diversity, with the hope that individuals can be reintroduced to the wild. Research, public education, and breeding programs all contribute to that goal.
Ask: How does captive breeding affect a population’s genetic diversity?
Answer: Captive breeding increases a population’s genetic diversity by mating only the most genetically dissimilar animals. Also, as the program succeeds, there will be more individuals contributing to the gene pool.
Tell students: Efforts to save the giant panda include a comprehensive captive breeding and reintroduction program. In this picture, a specialist from China holds one of two twin pandas born at a zoo in Madrid, Spain.

13. Ecological Hot Spots
Tell students that research and experience show that the most effective way to conserve biodiversity is to protect entire ecosystems. That approach not only preserves the natural interactions of many species at once but also helps preserve important ecosystem functions. This effort is as difficult as it is important. The first challenge is setting aside land as parks and reserves. But after parks and reserves are created, they must be protected from poachers, illegal logging, and other harmful activities.
Point out to students that another challenge is identifying areas that are large enough and that contain the right resources to protect biodiversity. That’s why biologists have identified ecological “hot spots,” shown in red in the illustration.
An ecological hot spot is a place where significant numbers of species and habitats are in immediate danger of extinction. Focusing conservation efforts in these areas can help save as many species as possible.
Tell students that Conservation International identifies biodiversity hot spots using two criteria. First, the area must contain at least 1,500 species of native vascular plants. Second, it must have lost at least 70 percent of its original habitat. The 34 hot spots seen here cover just 2.3 percent of Earth’s land surface, but they contain over 50 percent of the world’s plant species and 42 percent of its terrestrial vertebrates.
Ask: What does Conservation International hope will result from identifying these ecological hot spots around the world?
Answer: Conservation International hopes scientists and countries will direct their efforts at conserving biodiversity in these areas.
Ask for a volunteer to point out the ecological hot spot that includes part of the continental United States.
Click to confirm the student’s selection and zoom in on it.
Explain that this ecological hot spot (the California Floristic Province) includes most of the California coast and some of inland California.
Point out that one endangered species in this area is the California condor.

14. Ecology and Local Interests
Nature reserves as ecotourist attractions
Payment or tax incentives
Carbon credits
Explain to students that the greatest challenge to conserving biodiversity is making certain that people who live near protected areas benefit from conservation. Protecting nature reserves often requires individuals to change their habits or even the way they earn their living.
It is helpful to offer rewards or incentives to communities involved.
One model encourages the use of nature reserves as ecotourist attractions.
Click to reveal this bulleted item.
For this approach to work, local people and communities, rather than foreign investors, must profit from ecotourism. A number of countries in Africa, Central America, and Southeast Asia are experimenting with this approach.
Click to reveal the second bulleted item.
Another strategy is to offer payment or tax incentives to farmers and other landholders to encourage them to plant trees along rivers and streams. These plantings function as wildlife corridors to connect otherwise isolated forest fragments. In addition, this kind of tree planting helps improve water quality in rivers and streams and improve the health of the livestock, which can benefit from shade on hot days.
Click to reveal the third bulleted item.
On a global scale, carbon credits are one strategy aimed at encouraging industries to cut fossil fuel use. Companies are allowed to release a certain amount of carbon into the environment. If they release less carbon, they can sell credit for that carbon at a set market value or they can trade it to other companies. This encourages industries to pay for lower-emission machinery and to adopt carbon-saving practices. When this works, pollution can be reduced without adding a financial burden to industry, thus protecting both the economy and biodiversity.
Ask: When does conservation work best?
Answer: Conservation works best when it is informed by solid scientific information and benefits affected communities.

15. medicine habitats species ecosystems communities agriculture
Overview
medicine habitats species ecosystems communities agriculture
Areas that benefit from biodiversity include , , and the stability and adaptability of ecosystems.
Humans reduce biodiversity by altering
Conserving biodiversity includes protecting , preserving habitats and ecosystems, and involving local .
medicine
agriculture
habitats
ecosystems
Review with students the key points of this lesson through a matching activity.
Ask for volunteers to fill in the blanks in the sentences using the words provided.
Click to reveal the correct answers.
Remind students that biodiversity’s benefits include offering invaluable contributions to medicine and agriculture, maintaining ecosystem goods and services, and enabling organisms and ecosystems to adapt to environmental change.
Tell students: Humans reduce biodiversity by altering habitats, hunting, introducing invasive species, releasing pollution into food webs, and contributing to climate change.
Restate that conserving biodiversity includes protecting individual species, preserving habitats and ecosystems, and making certain that human neighbors of protected areas benefit from participating in conservation efforts.
communities

16. Student Worksheet Answers
Remind students that they should have used their worksheet to help define biodiversity and related terms throughout the lesson.
Give students time to work individually or in small groups to review their selection of terms for the word map. Allow students to make suggestions to one another regarding what would be helpful in the word map.
Worksheet Answers:
The word “biodiversity” should be in the top box of the word map along with its definition.
Student answers in the remainder of the boxes of the word map will vary, but should include the following terms:
- Ecosystem diversity
- Species diversity
- Genetic diversity
- Habitat fragmentation
- Ecological hot spot
Details and illustrations on each of these should be included in the student’s notes.