Essentials of Ecology

76 CHAPTER 3 Ecosystems: What Are They and How Do They Work? LEARNING ONLINE Log on to the Student Companion Site for this book ...

use old gator nests for incubating their eggs. These alligators eat large numbers of gar, a predatory fish. This helps maintain ...

78 Links: refers to the Core Case Study. refers to the book’s sustainability theme. indicates links to key concepts in earlier c ...

CONCEPT 4-1 79 Species diversity is the most obvious, but not the only, component of biodiversity. Another important compo- nent ...

80 CHAPTER 4 Biodiversity and Evolution The earth’s biodiversity is a vital part of the natu- ral capital that keeps us alive. I ...

CONCEPTS 4-2A AND 4-2B 81 The Fossil Record Tells Much of the Story of Evolution Most of what we know of the earth’s life histor ...

82 CHAPTER 4 Biodiversity and Evolution The first step in this process is the development of genetic variability in a population ...

CONCEPTS 4-2A AND 4-2B 83 Note that natural selection acts on individuals, but evolution occurs in populations. In other words, ...

84 CHAPTER 4 Biodiversity and Evolution traits already present in a population’s gene pool or for traits resulting from mutation ...

CONCEPT 4-3 85 These long-term climate changes have a major ef- fect on biological evolution by determining where different type ...

86 CHAPTER 4 Biodiversity and Evolution How Do New Species Evolve? Under certain circumstances, natural selection can lead to an ...

CONCEPTS 4-4A AND 4-4B 87 of years—making it difficult to observe and document the appearance of a new species. Learn more about ...

88 CHAPTER 4 Biodiversity and Evolution SCIENCE FOCUS We Have Developed Two Ways to Change the Genetic Traits of Populations wha ...

CONCEPT 4-5 89 Some biologists argue that a mass extinction should be distinguished by a low speciation rate as well as by a hig ...

90 CHAPTER 4 Biodiversity and Evolution species (low species evenness). Biologist Terry Erwin found an estimated 1,700 different ...

CONCEPTS 4-6A AND 4-6B 91 Each Species Plays a Unique Role in Its Ecosystem An important principle of ecology is that each spe- ...

92 CHAPTER 4 Biodiversity and Evolution often tolerate a wide range of environmental conditions. Flies, cockroaches (see Case St ...

CONCEPTS 4-6A AND 4-6B 93 Some people tend to think of nonnative species as villains. In fact, most introduced and domesticated ...

94 CHAPTER 4 Biodiversity and Evolution Amphibians were the first vertebrates to set foot on the earth. Historically, they have ...

CONCEPTS 4-6A AND 4-6B 95 Viral and fungal diseases, especially the chytrid fun- gus, which attacks the skin of frogs, apparen ...