1. Lesson 8.2 Species Interactions
The zebra mussel has completely displaced 20 native mussel species in Lake St. Clair.

3. Objectives Explain the difference between niche and habitat.
Give examples of parts of a niche.
Describe the five major types of interactions between species.
Explain the difference between parasitism and predation.
Explain how symbiotic relationships may evolve.

4. Lesson 5.2 Species Interactions
The Niche
Describes an organism’s use of resources and functional role in a community. A niche is different from a habitat. An organism’s habitat is a location. However, a niche is an organism’s pattern of use of its habitat.
Often restricted by competition

5. Ways in Which Species Interact
Interactions between species are categorized at the level where one population interacts with another.
The five major types of species interactions are:
Competition
Predation
Parasitism
Mutualism
Commensalism

6. Lesson 5.2 Species Interactions
Competition
Organisms compete when they seek the same limited resource.
In rare cases, one species can entirely exclude another from using resources.
To reduce competition, species often partition resources, which can lead to character displacement.
Intraspecific Competition: among members of same species
Interspecific Competition: among members of two or more different species

7. 4 Types of Competition Competitive Exclusion
Direct competition between species resulting in a winner and loser
One species is very effective competitor by excluding another species from resources entirely
Occurs when two or more species try to occupy the same exact niche

8. Fundamental and Realized Niche
Full niche of species
Realized
Niche restricted by competition

9. Resource Partitioning
Species partition, or divide, the resources they use in common by specializing in different ways

10. Character Displacement
When resource partitioning can lead to the evolution of physical characteristics among the competing species that reflect their specialized role in the environment.

11. Lesson 5.2 Species Interactions
Predation (+/–)
The process by which a predator hunts, kills, and consumes prey
Defensive traits such as camouflage, mimicry, and warning coloration have evolved in response to predator-prey interactions.
Some predator-prey relationships are examples of coevolution, the process by which two species evolve in response to changes in each other.
Rough-Skinned Newt
Did You Know? A single rough-skinned newt contains enough poison to kill 100 people. Unfortunately for the newt, its predator, the common garter snake, has coevolved resistance to the toxin.

12. Predators and Prey
All organisms need food and consumers must eat other organism to get it.
Predators
Consumers that actively hunt other organisms
Prey
Organisms upon which the predators feed on

13. Predator vs Prey
Size of predator and prey populations are closely linked
Large prey population=more predators
Small prey population=less predators
Population Cycles
Time it takes for a population to rise and fall
Some take 10 years, some 4 years
Lifespan of organisms plays a role

14. Parasitism
A relationship in which one organism feeds on the tissues or body fluids of another.
Examples: Ticks, Fleas, lice, variety of worms
Host
Organism in which the parasite feeds
True parasite
Adapted to live on or in the host

15. Parasitism Cont. Population size is related to size of host
Thrive in crowded host populations
Density-dependent limiting factor because parasite is more successful in a dense host population

16. Symbiosis Relationship where two species live together closely
Parasitism is a form of symbiosis
One organism is harmed while one benefits
Commensalism
Relationship that benefits one species and neither helps or harms the other
Barnacles on a whale

17. Symbiosis Cont. Mutualism Relationship where both species benefit
Ants and Acacia Tree
Flowers and Insects
A remarkable 3-way mutualism appears to have evolved between an ant, a butterfly caterpillar, and an acacia in the American southwest. The caterpillars have nectar organs which the ants drink from, and the acacia tolerates the feeding caterpillars. The ants appear to provide some protection for both plant and caterpillar.

18. Videos Predator Vs Prey Video Parasitism Symbiotic Relationships
Parasitism
Symbiotic Relationships

19. 8.2 Quiz 1. Explain how competition can affect an organism’s niche.
3. The human digestive tract is filled with bacteria. The bacteria live in the body and get nutrients while helping to digest food. What kind of species interaction is this-mutualism or commensalism? Is it symbiotic? Explain
4. Copy the chart below and place a (+) or (-) to indicate the species interaction.
Interaction
Effect on Species A
Effect on Species B
Commensalism
Competition
Herbivory
Mutualism
Parasitism
Predation