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Niches and Community Interactions Section 4.2 THINK ABOUT IT – If you ask someone where an organism lives, that person might answer “on a coral reef” or “in the desert.” – These answers give the environment or location, but ecologists need more information to understand fully why an organism lives where it does and how it fits into its surroundings. – What else do they need to know? The Niche – What is a niche? – A niche is: • the range of physical and biological conditions in which a species lives & the way the species obtains what it needs to survive and reproduce Tolerance – Every species has its own range of tolerance, the ability to survive and reproduce under a range of environmental circumstances. Tolerance – Environmental condition goes outside an organism’s optimum range--organism experiences stress • Ex: temperature – Organism uses more energy to maintain homeostasis --has less energy left for growth & reproduction – Organisms have an upper and lower limit of tolerance for every environmental factor – A species’ tolerance helps determine its habitat—the general place where an organism lives Defining the Niche – An organism’s niche describes • the environment where it lives • how it interacts with biotic and abiotic factors – Physical and biological aspects of its environment AND how the organism uses them to survive and reproduce Resources and the Niche – The term resource refers to any necessity of life • such as water, nutrients, light, food, or space. Resources Plants Animals - Sunlight - Nesting space - Water -Shelter - Soil nutrients - Types of food - Places to feed Physical Aspects of the Niche – Part of an organism’s niche includes: the abiotic factors it requires for survival • Ex: Most amphibians lose and absorb water through their skin so they must live in moist places • If an area is too hot and dry, or too cold for too long, most amphibians cannot survive Biological Aspects of the Niche – Part of an organism’s niche involves: the biotic factors it requires for survival, such as: • when and how it reproduces • the food it eats • the way in which it obtains that food – Ex: Birds on Christmas Island in the Indian Ocean all live in the same habitat but they prey on fish of different sizes and feed in different places. • each species occupies a distinct niche. WAYS ORGANISMS INTERACT Ways organisms interact COMPETITION ______________________ -Between SAME and DIFFERENT kinds of organisms -Compete with each other for available resources PREDATION __________________________ -Between DIFFERENT kinds of organisms -Hunt and kill other organisms to supply their energy needs COOPERATION __________________________ -Between SAME kind of organisms -Live together and help each other SYMBIOSIS __________________________ -Between DIFFERENT kinds of organisms -live in close association with another kind of organism COMPETITION Organisms in the same ecosystem try to compete with each other for the same available resources at the same time. FOOD Battle at Kruger http://www.youtube.com/watch?v=LU8DDYz68kM COMPETITION Organisms in an ecosystem have to compete with each other for available resources: shelter COMPETITION Organisms in an ecosystem have to compete with each other for available resources mates COMPETITION Organisms in an ecosystem have to compete with each other for available resources: space/territory Prairie dogs - 5 to 35 per acre Mountain lion- 1 male per 50-300 sq. mi COMPETITION Organisms in an ecosystem have to compete with each other for available resources: LIGHT The Competitive Exclusion Principle • Experiment shown in the graph – two species of paramecia (P. aurelia and P. caudatum) – first grown in separate cultures (dashed lines) with same conditions • both populations grew. – Then, both species were grown together in the same culture (solid line) • one species outcompeted the other • less competitive species did not survive. The Competitive Exclusion Principle – States that no 2 species can occupy exactly the same niche in exactly the same habitat at exactly the same time – One species will be better at competing for limited resources eventually exclude the other species – As a result, natural communities rarely have niches that overlap Dividing Resources – Instead of competing for similar resources, species usually divide them – Example: • 3 species of North American warblers shown all live in the same trees and feed on insects • But 1 species feeds on high branches; another feeds on low branches, and another feeds in the middle – The resources used are similar yet different – Each species has its own niche and competition is decreased COMPETITION If resources are scarce, some organisms will starve and populations will decrease. If resources become more plentiful, populations will increase. Competition in nature often results in a winner and a loser . . . with the loser failing to survive! SHORT SUPPLY If a nutrient is in _____________ CYCLES SLOWLY OR __________________ it will LIMIT the growth of the population LIMITING FACTOR = _____________ During this drought, there was not enough food available and many kangaroos starved. http://www.wspa-international.org/exhibition/gallery/large_DeadKenyan%20droughtSPANA.jpg Ways organisms interact PREDATION ___________________ Between DIFFERENT kinds of organisms Hunt and kill other organisms to supply their energy needs http://www.epa.gov/region5/superfund/ecology/images/fishcartoon.gif PREDATION Organisms in an ecosystem that capture and eat other organisms (prey) to supply their energy needs INTERDEPENDENCE All living and non-living things in an ecosystem are interconnected and changing even one thing impacts the whole ecosystem. 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 REMEMBER: EVERYTHING IS CONNECTED ! BIOLOGY; MIller and Levine; Prentice Hall; 2006 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. Ways organisms interact COOPERATION _____________ Between SAME kind of organisms Live together and help each other COOPERATION Same species live together in groups EX: herds, packs, colonies, families, etc Share food & childcare responsibilities Groom each other Take care of sick COOPERATION Same species live together in groups EX: herds, packs, colonies, families, etc Hunt in packs Provide protection Ways organisms interact SYMBIOSIS __________________________ Between DIFFERENT kinds of organisms Live in close association with another kind of organism http://www.zahnersatz.com/english/library/symbiosis.jpg 3 KINDS of SYMBIOSIS ______________________ MUTUALISM Both organisms benefit COMMENSALISM ______________________ One organism benefits; Other is neither harmed nor helped PARASITISM _____________________ One organism benefits; Other is harmed in some way 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” Insects transfer pollen between plants as they gather nectar for food. MUTUALISM “Good for me - Good for you” Clown fish get 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 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 COMMENSALISM “Good for me – Doesn’t bother you” http://www.geology.wmich.edu/gillespie/g322/Chapters/C16parasitism.whale.gif Barnacles are crustaceans that attach to the surface of whales and feed on the waters that pass by as the whale swims; the whale is not harmed PARASITISM “Good for me - Hurts you” Tick feeds on dog’s blood; Dog has discomfort, can get diseases/infection from bite Ecological Application: Wolves vs. deer Farmers Killed Wolves. What was the ramifications of this? Answer: Deer Population increased, Deer Ticks increased, ticks bite wild mice, Mice contain the disease Lyme, then if ticks bite humans they can infect humans. PARASITISM “Good for me - Hurts you” Tapeworms absorb food by living inside host intestine; host is harmed Species Interaction Video Clips: use with worksheet • • • • • • • • • Example 1: acacia tree ants: http://video.nationalgeographic.com/video/player/kids/animals-petskids/bugs-kids/ant-acacia-kids.html Example 2: Cordyceps: http://www.youtube.com/watch?v=XuKjBIBBAL8 Example 3: snail vs. parasitic worm: http://www.youtube.com/watch?v=EWB_COSUXMw Example 4: anaconda vs. mammal: http://www.youtube.com/watch?v=FDw0NdhK6QU&feature=channel Example 5: Whaleshark & Remora: http://www.youtube.com/watch?v=48eKFw7DDbY&feature=related Example 6: daddy long legs vs. aphid: http://video.nationalgeographic.com/video/player/kids/animals-petskids/bugs-kids/ant-acacia-kids.html example 7: polar bears: http://www.youtube.com/watch?v=hK8TQQp1qAA example 8: lions vs. hyenas: http://www.kewego.co.uk/video/iLyROoaftMFx.html example 9: meerkats: http://www.youtube.com/watch?v=X_eVEW_Y02o&feature=related Keystone Species – Sometimes changes in the population of a single species, often called a keystone species, can cause dramatic changes in the structure of a community. – In the cold waters off the Pacific coast of North America, for example, sea otters devour large quantities of sea urchins. – Urchins are herbivores whose favorite food is kelp, giant algae that grow in undersea “forests.” • For more explanation: http://lair2000.net/Mermaid_Lyrics6/lyrics/Sea_Otter_Rap.html Keystone Species – A century ago, sea otters were nearly eliminated by hunting. Unexpectedly, the kelp forest nearly vanished. – Without otters as predators, the sea urchin population skyrocketed, and armies of urchins devoured kelp down to bare rock. – Without kelp to provide habitat, many other animals, including seabirds, disappeared. – Otters were a keystone species in this community. Keystone Species – After otters were protected as an endangered species, their population began to recover. – As otters returned, the urchin populations dropped, and kelp forests began to thrive again. – Recently, however, the otter population has been falling again, and no one knows why.