1. Biodiversity
Chapter 4 Part I

2. 4-1 What Is Biodiversity and Why Is It Important?
Concept 4-1 The biodiversity found in genes, species, ecosystems, and ecosystem processes is vital to sustaining life on earth.
Concept 4-5 Species diversity is a major component of biodiversity and tends to increase the sustainability of ecosystems.
Identified ~1.8 million species

4. Species Diversity: Variety, Abundance of Species in a Particular Place
Species richness- # of different species
Species evenness- abundance of individuals within each of those species
Diversity varies with geographical location
Most species-rich communities
Tropical rain forests
Coral reefs
Ocean bottom zone
Large tropical lakes

5. Variations in Species Richness and Species Evenness
 High species evenness
High species richness 

6. Science Focus: Species Richness on Islands
Species equilibrium model, theory of island biogeography
Rate of new species immigrating should balance with the rate of species extinction
Island size
Smaller islands have less space, less resources, and less habitat diversity
Distance from the mainland
The farther a species travels, the less likely it is to make it to the island

7. How do we use this?
Habitat fragmentation
National Parks

8. 4-6 What Roles Do Species Play in Ecosystems?
Concept 4-6A Each species plays a specific ecological role called its niche.
Ecological niche, niche
Pattern of living
Concept 4-6B Any given species may play one or more of five important roles—native, nonnative, indicator, keystone, or foundation roles—in a particular ecosystem.

9. Niche separation Niche breadth
Specialist species
with a narrow niche
Generalist species
with a broad niche
Niche
separation
Number of individuals
Figure 4.11
Specialist species such as the giant panda have a narrow niche (left) and generalist species such as a raccoon have a broad niche (right).
Niche
breadth
Region of
niche overlap
Resource use
Fig. 4-11, p. 91

10. Specialized Feeding Niches of Various Bird Species in a Coastal Wetland

11. Niches Can Be Occupied by Native and Nonnative Species
Nonnative species; invasive, alien, or exotic species
May spread rapidly
Not all are villains

12. Indicator Species Serve as Biological Smoke Alarms
Can monitor environmental quality
Trout
Birds
Butterflies
Frogs

13. Viral & fungal diseases Climate change Overhunting
Adult frog
(3 years)
Viral & fungal diseases Climate change Overhunting
Young frog
Drought Habitat loss Nonnatives Pollution
Sperm
Tadpole develops
into frog
Sexual
reproduction
Tadpole
Figure 4.14
Life cycle of a frog. Populations of various frog species can decline because of the effects of harmful factors at different points in their life cycle. Such factors include habitat loss, drought, pollution, increased ultraviolet radiation, parasitism, disease, overhunting by humans, and nonnative predators and competitors.
UV radiation
Eggs
Fertilized egg
development
Egg hatches
Organ formation
Fig. 4-14, p. 94

14. Keystone, Foundation Species Determine Structure, Function of Their Ecosystems
Keystone species
Pollinators
Top predator
Foundation species
Create or enhance their habitats, which benefit others
Elephants
Beavers

15. Evolution
Chapter 4 Part II

16. 4-2 Where Do Species Come From?
Concept 4-2A The scientific theory of evolution explains how life on earth changes over time through changes in the genes of populations.
Concept 4-2B Populations evolve when genes mutate and give some individuals genetic traits that enhance their abilities to survive and to produce offspring with these traits (natural selection).

17. The Fossil Record Tells Much of the Story of Evolution
Fossils
Physical evidence of ancient organisms
Reveal what their internal structures looked like
Fossil record is incomplete: why?

18. Fossilized Skeleton of an Herbivore that Lived during the Cenozoic Era

19. Evolution If it happens & works, it keeps happening…
If it happens = mutation
It works = beneficial mutation
It keeps happening = reproduction
Allows it to continue in the population through natural selection

20. Individuals in Populations with Beneficial Genetic Traits Can Leave More Offspring
Natural selection: acts on individuals
Second step in biological evolution
Adaptation may lead to differential reproduction
Genetic resistance
When environmental conditions change, populations
Adapt
Migrate
Become extinct

21. Peppered moth

22. Three Common Myths about Evolution through Natural Selection
“Survival of the fittest” is not “survival of the strongest”
Strong, opposable thumbs
Walk upright
Complex brains
Organisms do not develop traits out of need or want
No grand plan of nature for perfect adaptation

23. Geologic Processes Affect Natural Selection
Tectonic plates affect evolution and the location of life on earth
Location of continents and oceans
Species physically move, or adapt, or form new species through natural selection
Earthquakes
Volcanic eruptions

24. 225 million years ago 135 million years ago 65 million years ago
Present
Figure 4.6
Over millions of years, the earth’s continents have moved very slowly on several gigantic tectonic plates. This process plays a role in the extinction of species, as land areas split apart, and also in the rise of new species when isolated land areas combine. Rock and fossil evidence indicates that 200–250 million years ago, all of the earth’s present-day continents were locked together in a supercontinent called Pangaea (top left). About 180 million years ago, Pangaea began splitting apart as the earth’s tectonic plates separated, eventually resulting in today’s locations of the continents (bottom right). Question: How might an area of land splitting apart cause the extinction of a species?
Stepped Art
Fig. 4-6, p. 85

25. Changes in Ice Coverage in the Northern Hemisphere During the last 18,000 Years

26. 4-4 How Do Speciation, Extinction, and Human Activities Affect Biodiversity?
Concept 4-4A As environmental conditions change, the balance between formation of new species and extinction of existing species determines the earth’s biodiversity.
Concept 4-4B Human activities can decrease biodiversity by causing the premature extinction of species and by destroying or degrading habitats needed for the development of new species.

27. How Do New Species Evolve?
Geographic Reproductive isolation isolation

28. Golden Toad of Costa Rica, Extinct