Environmental Science Chapter 8

25 July 2022
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question
Which regions of the world tend to have the greatest species richness?
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regions near the equator. The latitudinal gradient is one of the most obvious patterns in ecology, yet it is very difficult to explain.
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Genetic diversity provides the raw material for adaptation to local conditions.
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A more genetically diverse population is more likely to adapt to changing environmental conditions.
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Species richness is the number of species in an area
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This is the most common measure of species diversity.
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Biodiversity is the diversity of life at what level(s) of biological organization?
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genetic, species, and ecosystem levels. Species diversity is the most common type of biodiversity, but biodiversity encompasses these other levels as well.
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Which of the following would be the most reasonable estimate of the number of species on the planet?
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10 million. Estimates range from 3 million to 100 million.
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Global biodiversity exists in a number of patterns. The largest and most obvious of these is that biodiversity is greatest at the equator and drops as you move farther north or south
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This pattern is seen whether we look at trees, birds, amphibians, mammals, or most other types of organisms.
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Which group of organisms is contributes the most species to global biodiversity?
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insects. Insects provide over 40% of the species on the planet, far more than the next closest (plants, with around 15%).
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Why can many different species coexist and thrive in areas close to the equator?
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Stable equatorial climatic conditions discourage any one species from dominating the ecosystem and encourage biodiversity. Plant productivity and climate stability lead to more plant growth, making areas more productive and able to support larger numbers of species. This discourages single species from dominating the area and allows more species to coexist.
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Habitat fragmentation is the gradual piecemeal degradation of an area by such activities as logging and road building.
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Habitat fragmentation is the most common form of habitat destruction.
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Extirpation is the term we use when a population disappears from a given area but not globally.
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The disappearance of a particular population from a given area is called extirpation, but the species may persist in other areas.
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At the end of the Permian period, close to 90% of all species are thought to have gone extinct
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This was the most severe episode of extinction and occurred 248 million years ago.
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Today's extinction rate is approximately 100-1000 times greater than the background extinction rate.
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The rate is projected to further increase in the coming decades.
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If a conservation biologist wanted to try to stop the largest cause of species extinction, what should he or she focus on?
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habitat destruction. by far the most important factor in extinction.
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The sixth mass extinction event is ongoing and has been caused by human disturbance
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Human activities have denuded habitats; polluted the soil, air, and water; and hunted many large animals to extinction (e.g., cave bear, Irish elk, European buffalo, and moa).
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Which of the following is an example of the single greatest cause of species extinction?
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habitat fragmentation caused by building a road through a forest. Farming, logging, and road building break habitats into fragments, which isolates and reduces the size of populations.
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When a species declines in number, it also occupies less area than it once did
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When a species declines in number, its geographic range often shrinks as it is extirpated from part of its range.
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Which of the following types of species would be most vulnerable to overharvesting by people?
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whales. Whales are long-lived and produce few young at a time. Such organisms are quite vulnerable to hunting by humans.
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All of the following are ways that humans reduce biodiversity in ecosystems EXCEPT zoos
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Zoos are often involved in captive breeding programs, which are one small way that humans are trying to reintroduce endangered species to their native environments.
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Ecosystem services provide(s) a benefit to humans free of charge.
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Ecosystems provide many services to us free of charge. These services are not often taken into account when we evaluate the benefits of biodiversity.
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Which one of the following is an ecosystem service?
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purification of water. Intact ecosystems purify water.
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The development of pharmaceutical products has been
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aided by protection of ecosystem diversity. The pharmaceutical industry supports the principles of biodiversity. Each species of organism (particularly plants) can be regarded as a factory for novel chemicals, so the loss of any one species could mean the loss of a new drug.
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Which of the following statements about the importance of organisms in an ecosystem is true?
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"Ecosystem engineers" can be as important as keystone species for the survival of the ecosystem. Loss of an ecosystem engineer in an ecosystem could affect the vegetation, soil quality, and populations of predators and prey.
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Pharmaceuticals produced from wild species generate up to $150 billion in sales and save many lives each year. This is an example of ecosystem services
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Ecosystem services are provided by ecosystems and benefit humans and other organisms.
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Maria loves to be outdoors. She hikes every day in the woods, near the home that she shares with five pets. Maria's lifestyle provides evidence of biophilia
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Edward Wilson would argue that Maria has an intrinsic love and need for nature, and her choices and activities support this notion.
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The primary legislation for protecting biodiversity in the United States is the Endangered Species Act
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The ESA forbids the government and private citizens from taking actions that destroy endangered species or their habitat
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In captive breeding programs, organisms are bred with the intent to release them to the wild
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Organisms are bred and raised in controlled conditions with the intent of reintroducing them into the wild. Some programs have been successful (e.g., California condors), while others have been more controversial (e.g., gray wolves being reintroduced into Yellowstone National Park).
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The Endangered Species Act is often a center of controversy because landowners are concerned that federal officials will restrict the use of private land if threatened or endangered species are found on it
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The ESA has stopped few development projects, so this fear is overblown.
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Which of the following best describes a biodiversity "hotspot"?
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A hotspot is a region where species diversity is high but threatened by habitat loss. "Hotspot" regions in the world cover only 2.3% of Earth's surface but contain 50% of its plant species.
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Conservation biology is different from other fields of science discussed in the book because it is an applied and goal-oriented science, with implicit values and ethical standards
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Other fields of science try to remain objective, but conservation biology starts with the idea that species and biodiversity need to be protected.
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CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora) tries to prevent the extinction of species by asking countries to stop the international trade of body parts of endangered species
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International meetings decide which species should be banned and set trade quotas for others. Individual nations then need to enforce the bans.
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How is community-based conservation different from more traditional approaches to conservation?
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In community-based conservation, local people are involved with protecting the habitat of endangered species, allowing them to still gain benefit from its resources.
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Which of the following best describes an umbrella species?
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a species whose protection will result in the protection of a large number of species that require the same habitat
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Which of the following statements about cloning organisms is true?
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Producing cloned animals and keeping them in zoos does not increase biodiversity of the species. Keeping cloned animals out of the wild will not help to increase biodiversity.
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Which of the following organisms is the focus of a major captive breeding program?
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California condor. Condor numbers declined to only 22 birds before they were brought into captivity.