Chapter 18 Biodiversity and Threatened Habitats

Overview

In the shadow of trees over 60 m tall (more than 200 feet, or as high as a 17-story building), workers use bulldozers and other heavy equipment to clear a path 100 m wide (328 feet, over twice the width of an American football field) through a tropical forest. They are building a new road that will bring commerce and communications to the people of the region and will enable them to send their agricultural products, crafts, and minerals to markets in faraway countries. For each kilometer (0.62 mile) of roadway, they are destroying 10 hectares (about 24.7 acres) of tropical rainforest. The building of the road brings many high-paying jobs to the workers who build it, and the road will also open up new land for agriculture and human settlement, a process that will destroy even more forest. The trees are important in themselves, and also because they provide habitat (a set of environmental conditions that make up a place to live) for thousands of species.

The number and variety of species in a place are referred to as biological diversity or, simply, biodiversity. Biodiversity is measured most easily by the number of distinct species present. More broadly, biodiversity also includes genetic diversity within species and ecological diversity within habitats or ecosystems. In this chapter we consider the importance of biodiversity, the conditions that support biodiversity, some of the threats to biodiversity, and some ways in which humans can reduce these threats.

Recall from Chapter 5 that species are reproductively isolated groups of interbreeding natural populations. Most new species originate by a process of geographical speciation, in which reproductive isolation evolves during a period of geographic separation. The processes that give rise to new species increase biodiversity, while the processes that result in the extinction of species decrease biodiversity.

Chapter Outline

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Review Questions

THE PURPOSE of these review quizzes is to guide students in where their knowledge and understanding is strong, where it is weak, and where time should best be spent in studying.

CHAPTER 18:

  • What is a biological community?   What is an ecosystem?  What is biodiversity?  Explain at least four reasons why biodiversity is important for humans.  What theory best explains the relationship between energy, biodiversity, and ecosystem stability?  Why are topical ecosystems more diverse than Arctic ecosystems?  (If you cannot explain these things, or if you are not sure, then you need to reread Section 18.1.)
  • What major processes increase biodiversity?  What major processes decrease biodiversity?  What are the major threats to biodiversity today, and why?  What is the difference between pseudoextinction and true extinction?  What are ‘living fossils’?  Name at least four ‘living fossils’.  What are some causes of mass extinctions?  What theory best explains the extinction of the dinosaurs and other forms of Mesozoic life?  What is the evidence for this theory?  What theory best explains the extinctions of the last million years?  Which species are in danger of extinction today, and what are the best ways of predicting this?  What are the best remedies that can help prevent impending extinction?  (If you cannot explain these things, or if you are not sure, then you need to reread Section 18.2.)
  • Why are tropical rainforests so biologically diverse?  Why are they important to the biosphere as a whole?  How do they influence weather patterns?  How do people living far from the tropics benefit from tropical ecosystems?  What are some current threats to tropical ecosystems?  What practices can help reduce some of these threats?  Explain at least three examples of the kind of mutualism that helps sustain tropical biodiversity. What is desertification, and how can we best control it?  What is ecotourism, and what are some of its benefits and challenges?  (If you cannot explain these things, or if you are not sure, then you need to reread Section 18.3.)

Open Response Study Questions

These questions are designed to assess your understanding of the topics explored in this chapter. You can use these questions in three ways:

Before you start …

Read through the questions before you read the chapter to help prime you to read the text more carefully and strategically. Remember that you are just starting out on your learning journey, so don’t feel disheartened if you don’t know how to answer them yet!

Whilst you read …

As you work through the chapter, have another go at answering the questions to see how you are progressing. You can also answer the questions with the textbook open in front of you, in order to create model answers that can be used to refer back to later.

At the end …

Answer the questions once you have finished reading to see what you have learned. Check your responses against your model answers and use these to identify any gaps in your understanding.

DEFINITIONS:

In your own words, define ANY TWO of the following terms:

epiphyte          “slash and burn”          coelacanth (Latimeria)            canopy            community

biome

ESSAYS:

Answer any two of the following questions.  Make sure to answer all parts of any question you choose.

1. Explain why coral reefs are threatened today, and what some of the possible consequences are.

2. (A) What is energy-stability-area (ESA) theory?  (B) What does it attempt to explain?  (C) How does it      do so (describe at least two ways).

3. Explain why the extinction of orangutans would threaten the diversity of many other animal and plant species.

4. (A) Name at least four species threatened with extinction, and (B) in each case, tell what is being done to help conservation of this species so that it does not become extinct.

5. (A) What is “slash and burn” agriculture?  (B) Why is it used?  (C) What are some of its consequences?

PowerPoint Slides

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Bibliography

Almeda, F., and C.M. Pringle. 1988. Tropical Rainforests: Diversity and Conservation. San Francisco: California Academy of Sciences and Pacific Division, American Association for the Advancement of Science.

Anderson, A.B., editor. 1990. Alternatives to Deforestation: Steps Toward Sustainable Use of the Amazon Rain Forest. New York: Columbia University Press

Archibald, J.D. 1996. Dinosaur Extinction and the End of an Era: What the Fossils Say. New York: Columbia University Press

Ashley, M.V. 1999. Molecular conservation genetics. American Scientist 87: 28-35.

B.B.C. News. 2021. U.S. declares 23 bird, fish, and other species extinct.  Https://www.bbc.com/news/world-us-canada-58740362

Barlow A. et al.  2018.  Partial genomic survival of cave bears in living brown bears.  Nature Ecol. Evol.  2: 1563-1570.

Bird, M. 2001. Noah’s new ark. Time Jan. 8, 2001: 60-61.

Blockhus, J.M., et al., editors. 1992. Conserving Biological Diversity in Managed Tropical Forests. Cambridge, UK: IUCN.

Boo, E. 1990. Ecotourism: the potentials and pitfalls. Washington: World Wildlife Fund.

Broadley M.W. et al.  2018.  End-Permian extinction amplified by plume-induced release of recycled lithospheric volatiles.  Nature Geoscience  11: 682-687. 

Brown, L.R. 1991. The World Watch Reader on Global Environmental Issues. New York: W.W. Norton.

Broad, R., and J. Cavanagh. 1993 Plundering Paradise. The Struggle for the Environment in the Philippines. Berkeley, CA: University of California Press.

Camara-Hernandez, J, and P.C. Manglesdorf. 1981. Perennial corn and annual teosinte phenotypes in crosses of Zea diploperennis and maize. Harvard Univ. Bussey Inst. Publication 10: 3-37.

Carvalho, M.R., et al. 2021. Extinction at the end-Cretaceous and the origin of modern Neotropical rainforests. Science, 372(6537): 63-68.  https://doi.org/10.1126/science.abf1969

DePalma, R.A., et al. 2022. A seismically induced onshore surge deposit at the KPg boundary, North Dakota.  Proc. Nat. Acad. Sci. 116(17): 8190-8199.  https://www.pnas.org/doi/10.1073/pnas.1817407116  https://doi.org/10.1073/pnas.1817407116

Donovan, S.K., editor. 1989. Mass Extinctions: Processes and Evidence. New York: Columbia Univ. Press.

Droser, M.L., R.A. Fortey, and X. Li. 1996. The Ordovician radiation. Amer. Sci. 84: 122-131.

Ecological Society of America. 2011. The story of the fig and its wasp. https://www.esa.org/esablog/2011/05/20/the-story-of-the-fig-and-its-wasp/

Ehrlich. P.R., and A.H. Ehrlich. 1981. Extinction. The Causes and Consequences of the Disappearance of Species. New York: Random House.

Eldredge, N. 1994. The Miner’s Canary: Unraveling the Mysteries of Extinction. Princeton, NJ: Princeton University Press.

Erwin, D.H. 1990. The end-Permian mass extinction. Ann. Rev. Ecol. & Systematics, 21: 69-91.

Erwin, D.H. 1993. The Great Paleozoic Crisis: Life and Death in the Permian. New York: Columbia University Press

Flannery, T. F. 1995. The Future Eaters. An Ecological History of the Australasian Lands and People. New York: Braziller.

Gay, K. 1993. Rainforests of the World: A Reference Handbook. Santa Barbara, CA: ABC-CLIO.

Gentry, A.H., editor. 1992. Four Neotropical Rainforests. New Haven: Yale Univ. Press

Goldfarb, T.D., editor. 1991. Taking Sides. Clashing Views on Controversial Environmental Issues, 4th ed. Guilford, CT: Dushkin Publishing Group.

Gore, R. 1989. Extinctions. Nat. Geog. June: 662-699

Grant, P.R. 1995. Commemorating extinctions. Amer. Sci. 83: 420-422.

Groombridge, B., and M.D. Jenkins. 2002. World Atlas of Biodiversity: Earth’s Living Resources in the 21st Century. Berkeley, CA: Univ. of California Press

Gulick S.P.S. et al. 2019.  The first day of the Cenozoic.  Proc. Nat. Acad. Sci. USA 116(39): 19342-19352.  https://doi.org/10.1073/pnas.1909479116   Https://www.pnas.org/content/early/2019/09/04/1909479116 

Hallam, A. 1997. Mass Extinctions and their Aftermath. New York: Oxford Univ. Press.

Heyer R. et al., 2014.  Measuring and monitoring biological diversity. Standard methods for amphibians. Washington, D.C.: Smithsonian Institution Press

Hurst, P. 1990. Rainforest Politics: Ecological Destruction in South-East Asia. London: Zed Books.

Huston, M.A. 1994. Biological Diversity: the coexistence of species on changing landscapes. Cambridge, UK: Cambridge University Press.

Iltis, H.H., et al. 1979. Zea diploperennis (Gramineae): a new teosinte from Mexico. Science, 203(4376): 186-188.  https://science.sciencemag.org/content/203/4376/186

IUCN Conservation Monitoring Centre. 1986. IUCN Red List of Threatened Animals. Gland, Switzerland: International Union for Conservation of Nature and Natural Resources.

Jacobs, M. 1981. The Tropical Rain Forest. A First Encounter. New York: Springer-Verlag.

Janzen, D.H. 1966. Coevolution of mutualism between ants and acacias in Central America. Evolution, 20(3): 249-275.

Janzen. D.H. 1974. Swollen-thorn Acacias of Central America. Washington: Smithsonian Institution Press.

Kauffman, S.A. 1995. Germinal velocity. The Sciences Sept./Oct.: 34-39.

Kellert, S.R. 1996. The Value of Life: Biological Diversity and Human Society. Washington, D.C.: Island Press/Shearwater Books.

Khor, K.P. 2002. Intellectual property, Biodiversity, and Sustainable Development: Resolving the Difficult Issues. London: Zed Books.

Kloor, K. 1999. Vanishing act: Is the law that protects endangered species itself endangered? The Sciences, Oct.-Nov. 1999, p. 14-17.

Kunich, J.C. 2003. Ark of the Broken Covenant: Protecting the World’s Biodiversity Hotspots. Westport, CT: Praeger.

Levin, D.A. 2002. Hybridization and extinction. Amer. Scientist 90: 254-261.

Lucas, G., and H. Synge. 1980. IUCN Plant Red Data Book. Gland, Switzerland: International Union for Conservation of Nature and Natural Resources.

Martin, P.S., and R.G. Klein, editors. 1984. Quaternary extinctions. Tucson: University of Arizona Press.

Mayr, E., and P.D. Ashlock. 1991. Principles of Systematic Zoology, 2nd ed. New York: McGraw-Hill.

McKee, J.K. 2003. Sparing Nature: the Conflict Between Human Population Growth and Earth’s Biodiversity. New Brunswick, NJ: Rutgers Univ. Press

Mittermeier, R.A., N. Myers, and C.G. Mittermeier. 1999. Hotspots: Earth’s biologically richest and most endangered terrestrial ecoregions. Mexico City: CEMEX Conservation International.

Moffett, M.W. 1999. Ants and plants: Friends and foes. National Geographic. May 1999: 100-113.

Murray, S.C., and R.W. Jessup. 2013. Breeding and genetics of perennial maize: progress, opportunities, and challenges. In: Perennial Crops for Food Security, Proceedings of the FAO Expert Workshop, August 28-30, 2013, Rome, Italy, pp. 103-111.

Myers, N. 1988. Threatened biotas: “Hot spots” in tropical forests. Environmentalist, 8: 187-208.

Myers, N. 1991. Tropical deforestation: the latest situation. Bioscience, 41: 282.

National Geographic Society. 1999. Biodiversity, the fragile web. National Geographic, February, 1999 (entire Issue devoted to this topic).

Newman, N. 2002. Tropical Rainforest: Our Most Valuable and Endangered Habitat with a Blueprint for its Survival into the Third Millennium, revised ed. New York: Checkmark.

Nitecki, M.H., editor. 1984. Extinctions. Chicago: University of Chicago Press.

Portland Audubon. 2021. Northern spotted owl.  https://audubonportland.org/our-work/protect/habitat-and-wildlife/imperiled-species/northern-spotted-owl-4/

Pringle, R.M. 2005. The origins of the Nile perch in Lake Victoria. BioScience 55(9): 780-787.  https://doi.org/10.1641/0006-3568(2005)055[0780:TOOTNP]2.0.CO;2

Raup, D.M. 1991. Extinction: Bad Genes or Bad Luck? New York: W.W. Norton.

Raup, D.M., and J.J. Sepkloski. 1984. Periodicity of extinctions in the geologic past. Proc. Natl. Acad. Sci. U.S.A. 81(3): 801-805.  https://doi.org/10.1073/pnas.81.3.801

Rice, R.E., R.E. Gullison, and W.I. Reid. 1997. Can sustainable management save tropical forests? Sci. Amer. April: 44-49.

Sanchez, J.J.et al. 2018. Ecology of teosinte. PlOs One, Feb. 16, 2018. https://doi.org/10.1371/journal.pone.0192676

Sherpa Guides. n.d. Aquatic Fauna in Peril. The Southeastern Perspective.  Decatur, GA: Lenz. https://sherpaguides.com/southeast/aquatic_fauna/index.html

Signor, P.W. 1990. The geologic history of diversity. Ann. Rev. Ecol. & Systematics, 21: 509-539.

Teitel, M., and Wilson, K.A.  1999.  Genetically engineered food:  changing the nature of nature.  New York: Simon & Shuster.

Temple, S.A. 1977. Plant-animal mutualism: coevolution with dodo leads to near extinction of plant. Science 197: 885-886.

Terborgh, J. 1992a. Diversity and the Tropical Rain Forest. New York: Scientific American Library.

Terborgh, J. 1992b. Maintenance of diversity in tropical forests. Biotropica, 24: 283-292.

Thomback, J., and M. Jenkins. 1982. The IUCN Mammal Red Data Book. Gland, Switzerland: International Union for Conservation of Nature and Natural Resources.

Thorne-Miller, B. 1999. The Living Ocean: Understanding and Protecting Marine Biodiversity, 2nd ed. Washington, D.C.: Island Press.

U.S. Fish & Wildlife Service. n.d. Bachman’s warbler, Vermivora bachmanii. Http://www.fws.gov/verobeach/MSRPPDFs/Bachmanswarbler.pdf

U.S. Fish & Wildlife Service. 2021. U.S. Fish and Wildlife Service proposes delisting 23 species from Endangered Species Act due to extinction.  Https://www.fws.gov/news/ShowNews.cfm?ref=u.s.-fish-and-wildlife-service-proposes-delisting-23-species-from-&_ID=37017

Ward, P.D. 2000. Rivers in Time: The Search for Clues to Earth’s Mass Extinctions. New York: Columbia University Press

Wells, S.M., R.M. Pyle, and N.M. Collins. 1983. The IUCN Invertebrate Red Data Book. Gland, Switzerland: International Union for Conservation of Nature and Natural Resources.

Whitmer, M.C., and A.S. Cheke. 1991. The dodo and the tambalacoque tree: an obligate mutualism reconsidered. Oikos, 61(1): 133-137. https://doi.org/10.2307/3545415

Whitmore, T.C. 1991. An Introduction to Tropical Rain Forests. Oxford: Clarendon Press.

Whitmore, T.C., and J.A. Sayer, editors. 1992. Tropical Deforestation and Species Extinction. London: Chapman and Hall.

Wilkes, H.G. 1967. Teosinte: the closest relative of maize. Cambridge, MA: Busey Institute, Harvard University.

Wilson, D.E.  1996.  Measuring and monitoring biological diversity. Standard methods for mammals. Washington, D.C.: Smithsonian Institution Press

Wilson, E.O., editor. 1988. Biodiversity. Washington, D.C.: National Academy Press

Wilson, E.O., 1992. The Diversity of Life. New York: W. W. Norton.

Wood, A., P. Stedman-Edwards, and J. Mang, editors. 2000. The Root Causes of Biodiversity Loss. London: Earthscan.

World Conservation Monitoring Centre. 1992. Global blodiversity. Status of the Earth: living resources. New York: Chapman and Hall.

Chapter 19
Climate Change and Other Threats to the Biosphere