Ecological Interactions

“When one tugs at a single thing in nature, he finds it attached to the rest of the world.” 

~John Muir, naturalist, Sierra Club founder

What is a Niche?• A niche is a species way of

life, or the role the species plays in its environment.

• It includes: feeding relationships , reproduction, habitat and interactions with other organisms.

What is the Competitive Exclusion

Principle?• No 2 SPECIES occupy exactly the

SAME niche! Why?

• Competition!!

How do organisms interact in a community?

• Predation• Competition• Symbioses:

– Parasitism– Mutualism– Commensalism

What is Predation?• The predator captures, kills

and consumes another organism, the prey.

• Predators have evolved adaptations to increase their efficiency at capturing prey, ex. Sharp teeth, camouflage, spider web

• Prey have also evolved defenses against predators, ex. Sharp thorns, Poisons, Mimicry-resemble a poisonous species

•A decrease in the prey population means some predators will starve. Fewer predators mean prey population will increase.•Increase in prey means more food for predators. Predator population will increase until there is not enough food and the cycle repeats itself.

What is Competition?

• Competition results from a niche overlap between 2 or more species.

• Competition for food, shelter, mates, space or light.

• Only one organism will use the resources more efficiently (and win) that will eventually eliminate the other species.

COMPETITION

FOOD

Organisms in an ecosystem have to compete with each other for available resources.

http://www.harcourtschool.com/glossary/science/images/gr3/community3.jpg

http://www.knology.net/~sgoswald/Eating.jpg

COMPETITIONOrganisms in an ecosystem have to compete

with each other for available resources:

http://www.dpiw.tas.gov.au/inter.nsf/Images/LBUN-5K538R/$File/fox_adultandcub.jpghttp://www.gdccc.org/Records/EOY2004/NSEOY.htm

shelter

COMPETITIONOrganisms in an ecosystem have tocompete with each other for availableresources

mates

http://www.wasatchcomputers.net/gallery/elk_fight.jpg

http://www.biocrawler.com/w/images/thumb/3/34/200px-Peacock_courting_peahen.jpg

COMPETITIONOrganisms in an ecosystem have tocompete with each other for availableresources:

space/territory

http://www.rilanationalpark.org/gr.phtml?dir=../../pictures/in_text&img=/65_1180.jpg

http://www.elise.com/weblog/photos/prairie-dogs.jpg

Prairie dogs - 5 to 35 per acreMountain lion- 1 male per 50-300 sq. mi

COMPETITIONOrganisms in an ecosystem have to compete

with each other for available resources:

LIGHT

http://vilenski.org/science/safari/cellstructure/chloroplasts.htmlhttp://www.csjbacau.ro/gallery/images/Beech%20Tree%20Forest%20in%20Slanic%20Moldova.jpg

What are symbioses?

• Symbiosis= “living together”

• Close interaction (relationship) between 2 species living together–Parasitism–Mutualism–Commensalism

What is Parasitism?

• Involves a parasite that feeds off another organism, the host.

• Ex. Ticks, fleas, lice, leeches, tapeworms, malaria parasite, disease bacteria

• Parasites have evolved adaptations to exploit their host more efficiently

PARASITISM“Good for me - Hurts you”

Tick feeds on dog’s blood; Dog has discomfort, can get diseases/infection from bite

http://www.dogbreedinfo.com/guineafowltickphotos.htm

PARASITISM“Good for me - Hurts you”

Tapeworms absorb food by living inside host intestine; host is harmed

http://www.biology.ucok.edu/AnimalBiology/Platyhelminthes/tapeworms.jpg

PARASITISM“Good for me - Hurts you”

Barnacles are crustaceans that attach to the surface of whales and feed on their skin and fluids; Whale is harmed.

http://www.geology.wmich.edu/gillespie/g322/Chapters/C16parasitism.whale.gif

What is Mutualism?

• Mutualism is a cooperative relationship between 2 species in which both benefit.

• Neither can survive without the other.

• Ex. – Pollinators & Flowers– Birds & Rhinos– Clown fish & sea anemones

MUTUALISM “Good for me - Good for you”

Insects transfer pollen between plants as theygather nectar for food.

http://www.yksd.com/DistanceEdCourses/YKSDbiology/lessons/SecondQuarterLessons/Chapter5/5-5/images/3-way-mutualism.jpg

http://www.providence.edu/bio/faculty/adams/LECTUREProvCollegeMutualism.html

MUTUALISM“Good for me - Good for you”

Birds eat parasites living on the hides of giraffes and rhinos while enjoying protection from predators. Groomed animals lose their pests.

http://www.imbt.org/science.htm

http://www.hugheshome.net/jon/africa02/images/rhino_bird_JPG.jpg

MUTUALISM “Good for me - Good for you”

Clown fish gets protection from enemies by hiding out in poisonous sea anemones

http://www.zahnersatz.com/english/library/symbiosis.jpg

Sea anemone gets scraps of leftover food dropped by fish

What is Commensalism?

• Commensalism is an interaction in which one species benefits and the other is not affected.

• Ex.

–Hermit crabs & snail shells

–Pilot fish & sharks

COMMENSALISM“Good for me - Doesn’t bother you”

http://www.geology.wmich.edu/gillespie/g322/Chapters/C16shark.gif

Pilot fish receive scraps of food dropped by shark;Shark is neither harmed nor helped

COMMENSALISM“Good for me - Doesn’t bother

you”

http://www.abyssal.com/meeks/images/hermit_crab.jpg

Hermit crabs make homes in shells abandoned by snails;Snail is not harmed by crab

How do Organisms interact?

Predation +predator

-prey

Competition -Competitor 1

-Competitor 2

Parasitism +parasite

-host

Mutualism +Organism 1

+Organism 2

Commensalism

+Organism 1

0Organism 2

+ means “benefits” - means “harmed” 0 means “no affect”

ANY QUESTIONS?

Ecological Interactions Clock ?

• Clock ? #5: Create a VISUAL ILLUSTRATION explaining this information on p. 25– Ex. Diagram, flow chart, concept

map, etc.– Use the WHOLE page

• OR Clock ? #6: WRITE A LETTER/SHORT STORY explaining this information on p. 25– Use the WHOLE page