Summary

Biodiversity exists at multiple levels of organization, and is measured in different ways depending on the goals of those taking the measurements. These include numbers of species, genetic diversity, chemical diversity, and ecosystem diversity. Humans use many compounds that were first discovered or derived from living organisms as medicines: secondary plant compounds, animal toxins, and antibiotics produced by bacteria and fungi. Ecosystems provide ecosystem services that support human agriculture: pollination, nutrient cycling, pest control, and soil development and maintenance.

Loss of biodiversity threatens these ecosystem services and risks making food production more expensive or impossible. The core threats to biodiversity are human population growth and unsustainable resource use. Climate change is predicted to be a significant cause of extinction in the coming century. Exotic species have been the cause of a number of extinctions and are especially damaging to islands and lakes.

International treaties such as CITES regulate the transportation of endangered species across international borders. In the United States, the Endangered Species Act protects listed species but is hampered by procedural difficulties and a focus on individual species. The Migratory Bird Act is an agreement between Canada and the United States to protect migratory birds. Presently, 11 percent of Earth’s land surface is protected in some way. Habitat restoration has the potential to restore ecosystems to previous biodiversity levels before species become extinct. Examples of restoration include reintroduction of keystone species and removal of dams on rivers.

Review Questions

1. Bacteria that feed upon decaying organic matter in the soil would best be described as which one of the following?

A. Eukaryotic

B. Autotrophic

C. Fungi

D. Cyanobacteria

E. Heterotrophic

2. As Darwin recognized, populations evolve through natural selection when which of the following condition(s) are met?

A. Variation of traits among individuals

B. Competition for limited resources

C. More offspring are produced than can survive

D. All of the above

3. You are the world’s foremost expert on lizards. You have traveled the world extensively and have found that a particular species of lizard is found only in one desert near of the Chilean Andes. Which of following terms, with regard to its distribution, can be definitively applied to this species?

A. Endangered

B. Prokaryotic

C. Endemic

D. Disbursed

E. Clustered

4. Which one of the following is not a major cause of biodiversity loss?

A. Habitat loss

B. Climate change

C. Invasive Species

D. Zoonotic diseases

E. Overharvesting

5. Which one of the following statements is false?

A. There have been five mass extinctions preserved in the fossil record

B. Some bacteria are autotrophs

C. Current rates of extinction are higher than background extinction rates

D. Speciation is the process of creating new species

E. All living things can be classified into one of four taxonomic domains

6. During the middle of the 19th century, which scientist independently derived and proposed a theory of evolution that was similar to Darwin’s?

A. Gregor Mendel

B. Alfred Wallace

C. Isaac Newton

D. Rachel Carson

E. Niels Bohr

7. The study of the distribution of the world’s species both in the past and in the present is known by what term?

A. Geology

B. Biogeography

C. Biodiversity

D. Biogeomorphology

E. Ecological Succession

8. Which one of the following would be described as anthropogenic?

A. Water backing up behind a beaver dam

B. The dinosaurs going extinct

C. Logging a forest

D. A mudslide burying a stream

E. A volcanic eruption

9. By definition, what are you most likely to find in a biodiversity hotspot?

A. A large abundance of endangered species

B. A large number of endemic species

C. Mostly eukaryotic species

D. Extremophiles

E. Heat-loving microbes

10. You are working as a biologist for a team surveying biodiversity in the Amazon rainforest. You find a non-motile organism that grows in the soil, has eukaryotic cells, and is heterotrophic. Which one of the following could potentially describe this species?

A. Fungus

B. Animal

C. Bacteria

D. Plant

E. Archaea

See Appendix for answers

Attributions

OpenStax College. (2013). Concepts of biology. Retrieved from http://cnx.org/contents/b3c1e1d2-839c-42b0-a314-e119a8aafbdd@8.10. OpenStax CNX. Available under Creative Commons Attribution License 3.0 (CC BY 3.0). Modified from Original.

Page attribution: Essentials of Environmental Science by Kamala Doršner is licensed under CC BY 4.0.

“Review Questions” is licensed under CC BY 4.0 by Matthew R. Fisher.