Chapter Summary: Chapter 3
Biodiversity and Evolution
3-1 What is biodiversity and why is it important?
Biodiversity involves several levels including genetic, species, ecological, and functional diversity. It is a vital
renewable resource that keeps us alive as long as we live off of the biological natural income it provides.
CONCEPT 3-1 The biodiversity found in genes, species, ecosystems, and ecosystem processes is vital to sustaining
life on the earth.
1. What is biodiversity, and why is it vital to sustaining life on Earth?
2. Summarize the four main facets of biodiversity.
3-2 Where do species come from?
The process of biological evolution by natural selection occurs when genetic changes result in differential
reproduction, selecting those individuals with the adaptive trait. This results in populations that are better able to
survive and reproduce under existing environmental conditions. CONCEPT 3-2 According to the scientific theory
of evolution through natural selection, populations evolve when genes mutate and give some individuals genetic
traits that enhance their abilities to survive and to produce offspring with these traits.
3. Briefly describe the theory of evolution, being sure to include the roles played by variation within the
gene pool and natural selection. What are the limitations to natural selection? Summarize and address
three common misconceptions about evolution through natural selection.
4. What are fossils, and what information can they provide in terms of how life developed on Earth?
5. How can geologic processes, catastrophes, and climate change affect natural selection?
3-3 How do speciation, extinction, and human activities affect biodiversity?
Natural selection can lead to development of an entirely new species; in speciation, two species arise from one
usually as a result of geographic isolation and reproductive isolation. Extinction is normally a low-rate process that
occurs when organisms cannot adapt to some change in their environment. CONCEPT 3-3 As environmental
conditions change, the balance between formation of new species and extinction of existing species determines the
earth’s biodiversity.
6. Define speciation. Explain how geographic isolation and reproductive isolation can result in speciation.
7. Distinguish between background extinction and mass extinction.
8. Explain why we should be concerned about extinction of species.
3-4 What are biomes and how have human activities affected them?
Terrestrial parts of the earth are called biomes. Biomes are influenced by climate, latitude, and altitude. CONCEPT
3-4A Differences in average annual precipitation and temperature lead to the formation of tropical, temperate, and
cold deserts, grasslands, and forests, and largely determine their locations. CONCEPT 3-4B In many areas, human
activities are impairing ecological and economic services provided by the earth’s deserts, grasslands, forests, and
mountains.
9. Describe how climate affects the distribution of plant life on Earth. Compare the climate in deserts,
grasslands, forest, and mountains. Summarize the interactions of altitude, latitude, and biome type.
10. Explain how human activities are negatively impacting terrestrial biomes.
3-5 What are aquatic life zones and how have human activities affected them?
Freshwater life zones and ocean/marine life zones are the two types of aquatic life zones on the earth. Different
types of organisms, plant and animal, evolve in these aquatic zones, according to environmental conditions.
CONCEPT 3-5A The key factors determining biodiversity in aquatic systems are temperature, dissolved oxygen
content, availability of food, and availability of light and nutrients necessary for photosynthesis. CONCEPT 3-5B
Human activities threaten aquatic biodiversity and disrupt ecological and economic services provided by saltwater
and freshwater systems.
11. Evaluate the significance of the ecological contributions of the oceans. Distinguish between coastal
zones and open sea. List and compare the three principal zones of an ocean.
12. Distinguish between coastal and inland wetlands. Describe the ecological functions performed by
wetlands. Describe environmental problems associated with coastal and inland wetlands.
13. List and compare the four zones of a lake. Distinguish between oligotrophic and eutrophic lakes.
Describe stratification and a turnover in a lake.
14. Name three different human activities that are currently threatening aquatic life zones.