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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”