1. 4-5 What Is Species Diversity and Why Is It Important?
Concept 4-5 Species diversity is a major component of biodiversity and tends to increase the sustainability of ecosystems.

2. Species Diversity: Variety, Abundance of Species in a Particular Place (1)
An important characteristic of a community and the ecosystem to which it belongs is its species diversity, or the ________________ and ________________ of species it contains
Two important components of species diversity
Species _______________: The number of different species in a given area
Species _________________: comparative number of individuals of each species present
number
variety
richness
evenness

3. Variations in Species Richness and Species Evenness
Low
________ Species Richness
High
Figure 4.12: These two types of ecosystems vary greatly in species richness. An example of high species richness is a coral reef (left), with a large number of different species. On the other hand, this grove of aspen trees in Alberta, Canada (right) has a small number of different species, or low species richness.
Coral Reef
Grove of Aspen Trees
Fig. 4-12, p. 93

4. Species Diversity: Variety, Abundance of Species in a Particular Place (2)
Diversity varies with _________________ location
For most terrestrial plants and animals, species diversity is highest in the ______________ and declines as we move towards the ______________
The most species-rich communities
Tropical rain forests
Coral reefs
Ocean bottom zone
Large tropical lakes
geographic
tropics
poles

5. Science Focus: Species Richness on Islands
In the 1960s, Robert _____________ and Edward O. _____________ set out to discover why large islands have more species richness than small islands
They used their findings to propose
the ….
- species equilibrium model
- also called the theory of
__________ _______________
MacArthur
Wilson
island
biogeography
Edward O. Wilson

6. Science Focus: Species Richness on Islands
According to this widely accepted scientific theory, the species richness found on an island is determined by the interaction of two factors:
Rate of new species ____________________
Rate at which species become ________________
Immigration and extinction rates are affected by…
Island ______________
distance from the ___________________
immigration
extinct
size
mainland

7. Science Focus: Species Richness on Islands
Which would serve as a larger target for potential colonizers – a small island or a large island?
Which would have more resources –
a small island or large island?
Would potential colonizers be more
likely to reach an island close to the
mainland or far away?
Large island
Large island
Close to mainland

8. Species-Rich Ecosystems Tend to Be Productive and Sustainable
Species richness seems to increase ______________ and ________________ or sustainability, and provide insurance against catastrophe
How much species richness is needed is debatable
The theory of island biogeography has also been extended to study of _____________________
Areas such as national parks or mountain ecosystems that are surrounded by developed or fragmented land
productivity
stability
habitat islands

9. 4-6 What Roles Do Species Play in an Ecosystem?
Concept 4-6A Each species plays a specific ecological role called its niche.
Concept 4-6B Any given species may play one or more of five important roles—native, nonnative, indicator, keystone, or foundation—in a particular ecosystem.

10. Each Species Plays a Unique Role in Its Ecosystem
An important principle of ecology is that each species has a specific ____________ to play in the ecosystems where it is found
Ecological niche…often pronounced “nitch”
Involves everything that affects _____________ and ______________
Water, space, sunlight, food, temperatures
Not to be confused with a habitat…__________ where an organism lives
role
survival
reproduction
place

11. Each Species Plays a Unique Role in Its Ecosystem
Generalist species – have ____________ niches or a _____________ range of tolerance
They may live in many places, eat a variety of foods, often tolerate a wide range of environmental conditions
Specialist species - occupy ______________ niches
may only be able to live in one type of habitat, use only a few food sources, or tolerate a narrow range of climatic and environmental conditions
broad
wide
narrow

12. Specialist Species and Generalist Species Niches
Specialized
diet of
bamboo
Can eat a wide
variety of food…love
to dig through human garbage!
Endangered
due to
habitat
loss and slow
birth rates
Figure 4.13: Specialist species such as the giant panda have a narrow niche (left) and generalist species such as the raccoon have a broad niche (right).
Fig. 4-13, p. 95

13. Specialized Feeding Niches of Various Bird Species in a Coastal Wetland
Specialized niches ________________ competition, but are more
susceptible to degradation or environmental changes
reduce
Figure 4.14: This diagram illustrates the specialized feeding niches of various bird species in a coastal wetland. This specialization reduces competition and allows sharing of limited resources.
Fig. 4-14, p. 96

14. Case Study: Cockroaches: Nature’s Ultimate Survivors
Have been around for 350 million years, outliving the dinosaurs
3500 species
They have thrived because they are
_______________
Eat almost anything
Live in almost any climate (except the polar regions)
Antennae and sensors that allow ____________ responses
High reproductive rates – allows them to pass on beneficial traits like genetic ________________ to poisons
generalists
quick
resistance

15. Species Can Play Five Major Roles within Ecosystems
Native species - species that _________________ live and thrive in a particular ecosystem
Nonnative species – _______________ into or are ________________ to an ecosystem…also called invasive, alien, or exotic species
Indicator species – provide early _______________ of damage to a community or ecosystem
Keystone species – have a large ___________ on the types and abundance of other species
Foundation species – help to create or _______________ their habitats in ways that benefit other species
normally
migrate
introduced
warning
effect
enhance

16. Wild African Honey Bees “Killer Bees”
Nonnative species…imported into ____________ intentionally to help increase honey production
Ended up displacing
native bees and reduced
the honey supply
Have since moved through
Central America and the
Southern U.S.
Not gruesome killers, but they are ____________________ and unpredictable
Brazil
aggressive

17. Poison Dart Frog Indicator Species
Amphibians were the first __________________ to set foot on land and historically
have been good at adapting
to environmental changes
But since the 1980s, __________ amphibian species have been vanishing or declining worldwide
vertebrates
Figure 4.17: The well-known red-eyed tree frog (left) found in tropical rain forests in Mexico and Central America is currently not threatened with extinction. However, some species of the poison dart frog (right) found in the tropical forests of Brazil and southern Suriname are threatened with extinction, mostly because of an infectious fungus and habitat loss from logging and farming. This frog’s bright blue color warns predators that it is poisonous to eat. The toxic secretions of at least three of these species are used to poison the tips of blow darts that native peoples in the frog’s tropical habitat use for hunting.
many
Why are amphibians vanishing?
Fig. 4-17a, p. 98

18. Case Study: Why Are Amphibians Vanishing? (1)
Habitat loss and fragmentation
Prolonged drought
Pollution…exposure to _____________________ in ponds
Increase in UV radiation
Parasites…feed on amphibian ___________
Viral and fungal __________________…damages their skin and ability to take in water
Climate change…correlation to atmospheric ______________
Overhunting…____________________
Nonnative predators and competitors
pesticides
eggs
diseases
warming
frog legs

19. Case Study: Why Are Amphibians Vanishing? (2)
Importance of amphibians
Sensitive biological indicators of environmental ________________
Adult amphibians
Important ecological roles in biological communities
Eat ___________________
Serve as food in the __________________ of other aquatic organisms
Genetic storehouse of pharmaceutical products waiting to be discovered
Secretions have been used as __________________ and ___________________
changes
Insects (mosquitoes)
food webs
painkillers
antibiotics

20. Keystone Species Play Critical Roles in Their Ecosystems
Keystone species: roles have a large effect on the types and abundances of other species
____________________
pollinators
top predators
American Alligator

21. Case Study: Why Should We Care about the American Alligator?
1930s-1960s: Hunters and poachers – killed off alligators to near extinction in the U.S.
Importance of gator holes and nesting mounds
the depressions they form hold ____________________ during dry spells
Their nesting mounds are important _____________ and _________________ for other organisms
Without the American alligator, dozens of other species would __________________ from coastal wetland ecosystems
water
feeding sites
nesting grounds
disappear

22. Foundation Species Help to Form the Bases of Ecosystems
Foundation species - create or enhance their habitats, which benefit others
Elephants – push over, break, and uproot trees…creating __________ patches where new ___________ may grow
Benefits ______________ grazing animals
Accelerates nutrient _________________
Beavers – ecological ___________________....build dams which create ponds and wetlands
open
plants
small
cycling
engineers

23. Three Big Ideas
____________________ evolve when genes mutate and give some individuals genetic traits that enhance their abilities to survive and to produce offspring with these traits (also called natural selection.)
Human activities are ________________ earth’s vital biodiversity by causing the extinction of species and by disrupting habitats.
Each species plays a specific ecological role or _____________ in the ecosystem where it is found.
Populations
decreasing
niche

24. Review Questions
What is the difference between generalists and specialists?
Identify the vocab term associated with the role of each species…
killer bee certain amphibians
elephant American alligator
3. What effect does species richness have on an ecosystem?
(broad niche)
(narrow niche)
Nonnative (Brazil)
Indicator sp.
Foundation sp.
Keystone sp.
Increases productivity and stability