Community Community InteractionsInteractions

• Competition

• Predation

• Symbiosis

Figure Source: http://www.animalintelligence.org/images/deerbunny1.jpg

3 Major Types3 Major Typesof Community of Community InteractionsInteractions

Recall: What is a community?Recall: What is a community? Community = Community = assemblage of populations assemblage of populations

interacting with one another within the same interacting with one another within the same environmentenvironment

Organisms within a community interact with Organisms within a community interact with each other in 3 major ways:each other in 3 major ways:

- Competition- Competition

- Predation- Predation

- Symbiosis - Symbiosis

Let’s look at each of these interactions in Let’s look at each of these interactions in more detail.more detail.

What is What is Competition?Competition? CompetitionCompetition

Occurs when members of different species Occurs when members of different species try to utilize a resource (such as light, try to utilize a resource (such as light, space, or nutrients) that is in limited space, or nutrients) that is in limited supply.supply.

Results in a winner and a loser.Results in a winner and a loser. Think of sports teams when they compete.Think of sports teams when they compete.

Scenario #2 in our opening demonstrationScenario #2 in our opening demonstration

Competitive Exclusion PrincipleCompetitive Exclusion Principle No two species can occupy the same No two species can occupy the same

ecological niche in the same habitat at the ecological niche in the same habitat at the same time.same time.

What is Predation?What is Predation? PredationPredation

Occurs when one living organism Occurs when one living organism feeds on another living organism.feeds on another living organism.

Involves predator and preyInvolves predator and prey Predator = organism that feedsPredator = organism that feeds on another organismon another organism Prey = organism that is the foodPrey = organism that is the food Example: Lynx and bunnyExample: Lynx and bunny

In today’s lab, we’ll examine a In today’s lab, we’ll examine a predator-prey relationship.predator-prey relationship.

Figure Source: http://www.lynescreations.com/images/LynxAttackRabbit2.jpg

Mimicry- An Antipredator Mimicry- An Antipredator DefenseDefense 2 main types– Batesian & Mullerian2 main types– Batesian & Mullerian

Batesian MimicryBatesian Mimicry A harmless species resembles a A harmless species resembles a

poisonous or distasteful speciespoisonous or distasteful species The harmless mimic is protected b/c it The harmless mimic is protected b/c it

is often mistaken to be its dangerous is often mistaken to be its dangerous look-alikelook-alike

Example: A king snake (nonpoisonous) Example: A king snake (nonpoisonous) resembles a coral snake (poisonous)resembles a coral snake (poisonous) King Snake Coral King Snake Coral

SnakeSnake

Mimicry- An Antipredator Mimicry- An Antipredator DefenseDefense Mullerian MimicryMullerian Mimicry

When 2 or more dangerous or distasteful When 2 or more dangerous or distasteful species look similar.species look similar.

Each species involved benefits b/c a Each species involved benefits b/c a predator that encounters an individual predator that encounters an individual of 1 species will avoid similar of 1 species will avoid similar individuals.individuals.

Example: Bees & wasps have similar Example: Bees & wasps have similar patterns of alternating yellow & black patterns of alternating yellow & black stripes.stripes.

What is Symbiosis?What is Symbiosis? SymbiosisSymbiosis

Refers to the close interactions Refers to the close interactions between members of two species.between members of two species.

3 major types3 major types

► ► ParasitismParasitism

► ► CommensalismCommensalism

► ► MutualismMutualism

Let’s look at each type…Let’s look at each type…Figure Source: http://www.camacdonald.com/birding/CattleEgret(JM).jpg

ParasitismParasitism What is it?What is it?

A relationship in which one A relationship in which one organism lives on or in another organism lives on or in another organism and gets its nourishment organism and gets its nourishment from it.from it.

One organism is One organism is harmedharmed (host) and (host) and one organism one organism benefitsbenefits (parasite) (parasite)

Example:Example: Deer ticks on dogsDeer ticks on dogs Can you think of any others?Can you think of any others?

CommensalismCommensalism What is it?What is it?

Relationship in which one organism Relationship in which one organism benefitsbenefits and other organism is and other organism is not hurt or not hurt or helpedhelped..

One organism often provides a home One organism often provides a home and/or transport for the other organism.and/or transport for the other organism.

Example:Example: Barnacles that attach themselves to backs of Barnacles that attach themselves to backs of

whaleswhales The whale is not affected.The whale is not affected. The barnacles benefit from transportation and eat The barnacles benefit from transportation and eat

small food particles in the water.small food particles in the water. Can you think of any others?Can you think of any others?

MutualismMutualism What is it?What is it?

A relationship in which A relationship in which bothboth members members benefitbenefit..

Think of a “mutual agreement” Think of a “mutual agreement” both both parties benefit!parties benefit!

Example:Example: Bees and flowersBees and flowers..

Bee benefits because eatsBee benefits because eats

nectar (food).nectar (food). Flower benefits because the beeFlower benefits because the bee

spreads its pollen (reproduction).spreads its pollen (reproduction). Can you think of any others?Can you think of any others?

SymbiosisSymbiosis You can think of the various types of You can think of the various types of

symbiosis as almost a continuum…symbiosis as almost a continuum…

ParasitismParasitism Commensalism Commensalism MutualismMutualism

( + / - )( + / - ) ( + / 0 ) ( + / 0 ) ( + / + ) ( + / + )

An extreme

Helps one member

Hurts other member

In the middle

Helps one member

No affect on other member

An extreme

Helps both members

Checking your Checking your understanding– Quick understanding– Quick

QuestionsQuestions1.1. What is a community?What is a community?

2.2. What is the Competitive Exclusion Principle?What is the Competitive Exclusion Principle?

3.3. What is predation?What is predation?

4.4. What is the name of the symbiotic What is the name of the symbiotic relationship in which both organisms relationship in which both organisms benefit?benefit?

5.5. What is the name of the symbiotic What is the name of the symbiotic relationship in which one organism benefits relationship in which one organism benefits and other is not helped or harmed?and other is not helped or harmed?

6.6. What is the name of the symbiotic What is the name of the symbiotic relationship in which one organism benefits relationship in which one organism benefits but other is harmed?but other is harmed?

Find an exampleFind an example

Using a computer or a smart phone, Using a computer or a smart phone, please find one example of a please find one example of a predator/prey relationship, a predator/prey relationship, a symbiotic relationship (be able to symbiotic relationship (be able to determine the type: mutualism, determine the type: mutualism, commensalism or parasitism)commensalism or parasitism)

Please find examples that we haven’t Please find examples that we haven’t discussed in class.discussed in class.

Homework for tonight:Homework for tonight:

Read pages 128-147 about biomes.Read pages 128-147 about biomes.

We will be playing biome bingo and We will be playing biome bingo and doing an activity about biomes over doing an activity about biomes over the next two days.the next two days.

Unit 2 Test will be on Friday! 10/5Unit 2 Test will be on Friday! 10/5 In class review on Thurs. 10/4In class review on Thurs. 10/4