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Published byLee Joseph Modified over 9 years ago
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Natural Selection
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Natural Selection: A process by which characteristics that make an individual better suited to it's environment become more common in the species. Sometimes referred to as “survival of the fittest”
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How Does Natural Selection work? 1. Those with the unique characteristics best suited for their environment will survive and produce offspring. 2. End result = ADAPTATIONS
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English Peppered Moth –Natural selection in action camouflaged moth dark moth - random mutation not as common Soot covered tree England 1800’s
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Shell for protection Adaptations Behaviors or physical characteristics that allow organisms to live successfully in their environment Long neck to reach leaves Long shallow roots, needles to protect from animals
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Niche An organisms’ role in an ecosystem = niche. Niche and Habitat are different ◦Address of an organism = Habitat ◦“Job” or “Profession” = Niche Habitat = Forest Niche = produce oxygen provide home for birds Organism = tree
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Explain why two organisms cannot occupy the same niche: If two species occupy the exact same niche in nature, one will die off due to competition for limited resources.
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http://www.youtube.com/watch?v=D1aRSeT-mQE Video Link – Niche, Competition, Predation, and Symbiosis
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Three major types of interactions among organisms: Competition Predation Symbiosis
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Competition: The struggle between organisms to survive as they attempt to use the same limited resources.
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Predation: An interaction in which one organism kills another for food.
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Predator or Prey: Predator - organism that does the killing Prey – organism that is killed.
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Effect of predation on population size: What variable is plotted on the x-axis? ______ What two variables are plotted on the y-axis? ________ and __________ years # of moose # of wolves
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Effect of predation on population size: How did the moose population change between 1965 and 1972 ___________ How did the wolf population change between 1973 and 1976? __________ It increased
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Effect of predation on population size: How might the change in moose population have lead to the change in wolf population? – The wolf preys on the moose so more moose meant more food for the wolf.
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Effect of predation on population size: How might disease in the wolf population one year affect the moose population the next year? – Disease in the wolf population might cause some to die. With less predators, the moose population would most likely increase.
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Examples of Predator Adaptations Cheetah speed Owl eyes Jelly fish venom
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Defense Strategies of Prey Mimicry Protective Covering False Coloring Warning color Camouflage
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Video Link on Predator and Prey Interactions http://www.youtube.com/watch?v=vZynrBA91fY
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Interactions – Three Types
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Symbiosis – a close relationship in nature that benefits at least one species Termites Bacteria from gut of termite
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Symbiosis
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Mutualism Both species benefit
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Commensalism One species benefits, but the other isn’t harmed or helped.
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Parasitism One species benefits and the other is harmed. The one benefiting is the parasite The one being harmed is a host
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