8/14/2019 Ch. 5, Sec 2: Interactions in Communities p109-111 Section

1/12

Ch. 5, Sec 2: Interactions in Communities p109-111

Section 2: Interactions In Communities

How do predator-prey interactions influence bothpredators and prey?

How are plants protected from herbivores?

How does symbiosis work?

What are examples of all these relationship?

8/14/2019 Ch. 5, Sec 2: Interactions in Communities p109-111 Section

2/12

Ch. 5, Sec 2: Interactions in Communities p109-111

1) Predator-Prey Interactions

Predationis the act of one organism killinganother for food.

The predator is often bigger or more powerfulthan the prey (not always)

The prey population is larger than the predatorpopulation

The predator population usually follows the prey

8/14/2019 Ch. 5, Sec 2: Interactions in Communities p109-111 Section

3/12

Ch. 5, Sec 2: Interactions in Communities p109-111

Predator-Prey Interactions, cont.

See Visual Concept 60350: PREDATION

8/14/2019 Ch. 5, Sec 2: Interactions in Communities p109-111 Section

4/12

Ch. 5, Sec 2: Interactions in Communities p109-111

2) Herbivory

Herbivores are animals that eat plants.

Unlike predators, herbivores do not often kill the plants.But plants do try to defend themselves.

Plants defend themselves from herbivores with thornsand spines or with bad tasting chemical compounds.These chemical compounds may even cause sicknessor death.

See Visual Concept 60352: HERBIVORY

8/14/2019 Ch. 5, Sec 2: Interactions in Communities p109-111 Section

5/12

Ch. 5, Sec 2: Interactions in Communities p109-111

3) Other Interactions: Symbiosis

Not all interactions between organisms result in awinner and a loser.

Symbiosis is a relationship in which two species live in

close association with each other. One species benefits,and the other might or might not.

Three types of symbiosis:

1) Parasitism

Mutualism

Commensalism

8/14/2019 Ch. 5, Sec 2: Interactions in Communities p109-111 Section

6/12

Ch. 5, Sec 2: Interactions in Communities p109-111

Parasitism

In parasitism, a parasite feeds on another organismcalled a host.

The host is almost always larger than the parasite, and is

usually harmed but not intentionally killed.

Parasites often live on or in their host. Therefore, theparasite depends on its host not only for food but for aplace to live as well.

Examples: fleas, tapeworms, mosquitoes, ticks, leeches

8/14/2019 Ch. 5, Sec 2: Interactions in Communities p109-111 Section

7/12

Ch. 5, Sec 2: Interactions in Communities p109-111

Parasites, continued

Hosts try to keep parasites from infecting them. Hostscan defend themselves with their immune systems orbehaviors such as scratching.

In response, parasites may evolve ways to overcome thehosts defenses (immunity to drugs, for example)

See Protists and Humans (p.507-509) for more onparasites and disease.

8/14/2019 Ch. 5, Sec 2: Interactions in Communities p109-111 Section

8/12

Ch. 5, Sec 2: Interactions in Communities p109-111

QuickTime and a

mpeg4 decompressorare needed to see this picture.

8/14/2019 Ch. 5, Sec 2: Interactions in Communities p109-111 Section

9/12

Ch. 5, Sec 2: Interactions in Communities p109-111

Symbiosis, continued

A relationship between two species in which both

species benefit is called mutualism.

Cleaner fish & larger fish; sea anenome & clown fish

bees & flowers, fungi & algae

In commensalism, two species have a relationship in

which one species Is helped, but the other is neutral..

Orchids growing on forest trees to reach the sun

8/14/2019 Ch. 5, Sec 2: Interactions in Communities p109-111 Section

10/12

Ch. 5, Sec 2: Interactions in Communities p109-111

Summary of Symbiosis

QuickTime and ampeg4 decompressorare needed to see this picture.

8/14/2019 Ch. 5, Sec 2: Interactions in Communities p109-111 Section

11/12

Ch. 5, Sec 2: Interactions in Communities p109-111

Summary

1. Predators kill prey for food; populations are related

3. Herbivores eat plants, but plants can defend throughthorns, taste, or toxins

5. Symbiosis is close connection between two species; atleast one benefits

Relationship Species A Species BParasitism Helps Hurts

Mutualism Helps HelpsCommensalism Helps Neutral

8/14/2019 Ch. 5, Sec 2: Interactions in Communities p109-111 Section

12/12

Ch. 5, Sec 2: Interactions in Communities p109-111

Vocabulary List

Predation (predator, prey)

Herbivory

Symbiosis

Parasitism (parasite, host)

Mutualism

Commensalism