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What Factors Affect Populations in Ecosystems?

What Factors Affect Populations in Ecosystems?. Text 1.3: 36-40. Agenda. Minds On – Activity: Keeping a Balance How Do Organisms Interact? Competition Species Niche Predation Mimicry Symbiosis Inquiry Task – Symbiosis At Its Best! Limiting Factors & Carrying Capacity

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What Factors Affect Populations in Ecosystems?

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  1. What Factors Affect Populations in Ecosystems? Text 1.3: 36-40

  2. Agenda • Minds On – Activity: Keeping a Balance • How Do Organisms Interact? • Competition • Species Niche • Predation • Mimicry • Symbiosis • Inquiry Task – Symbiosis At Its Best! • Limiting Factors & Carrying Capacity • Case Study – Lynx & Hare • Consolidation – Analyze This!

  3. Learning Goal • By the end of the class I can • Describe biotic relationships within an ecosystem • Describe how these interactions effect the populations within the ecosystem

  4. Minds On – Keeping a Balance • Goal – organisms have to find resources in order to survive • Food = hand over stomach • Water = hand over mouth • Shelter = hands over head to make roof • Debrief • What are some factors that affected the survival of animals? • Did you notice any trends? • Did the animal population, rise, fall or stay the same?

  5. How Do Organisms Interact? Competition • The interaction of two or more organisms competingfor the same resources within a given habitat • May compete to mate, for resources, for preferable habitat, etc. • May result in slightly different species having slightly different niches • EX. Warblers

  6. What is a Species Niche? • Niche- organism’s use of the biotic and abiotic resources in an environment. • Competitive Exclusion Principle – two species in direct competition cannot occupy the same niche.

  7. What Are the Effects of Competition?

  8. How Do Organisms Interact? Predation • When an organism eats another as a food source • Both predator and prey have adapted strategies to help them hunt or prevent them from being hunted • Predator: Hawks have fabulous eyesight to aid in hunting • Prey: Porcupines have quills to prevent predators from wanting to attack them

  9. How Do Organisms Prevent Predation? • Mimicry of monarch butterfly by the victory butterfly • Both taste bad and similar marking make predators avoid both

  10. How Do Organisms Prevent Predation? Owl Butterfly Mimics the eyespots of an owl to scare off predators Leaf Butterfly Camouflages in leaf litter on the forest floor

  11. What is Symbiosis? • Many organisms are involved in symbiotic relationships with other organisms • Mutualism • Win- win • EX: Clownfish and sea anemones  • Parasitic • Win- Loose • Tick and Humans • Commensalism • Win- Neutral • Spider and plants

  12. What is Symbiosis? • Many organisms are involved in symbiotic relationships with other organisms

  13. What is Symbiosis?

  14. Inquiry Task – Symbiosis At It’s Best! • Research one example of a unique symbiotic relationship between two species: • Brief description of species involved • Type of symbiotic relationship • Visual information either a picture/video

  15. How Can We Describe Populations? • Equilibrium – number of deaths equals the number of births • How many people can the world sustain? • What limits human population?

  16. How Can We Describe Populations? • As a population grows each individual gets a smaller share of the resources • Organisms become stressed, some die, some are not able to reproduce. • Eventually the number of births is equal to the number of deaths = Equilibrium. • Carrying Capacity = the maximum number of individuals that an ecosystem can support without reducing its ability to support future generations of species. • What would cause a species to reach its carrying capacity?

  17. What Can Limit Population Size? • Limiting Factor – is an environmental factor that prevents an increase in the number of organisms in a population or prevents them from moving into new habitats. • Healthy populations have limiting factors that prevent overpopulation. • In order for population to be stable or sustainable it must never exceed its carrying capacity. What is an example of an abiotic limiting factor? What is an example of a biotic limiting factor?

  18. Case Study – Lynx & Snowshoe Hare • As population of hares (prey) increases the lynx can capture hares more easily. • Lynx = well feed increased offspring population increases. • Increase in Lynx causes a decrease in hare population due to predation. • As lynx food supply runs out lynx population will decrease • Finally fewer lynx causes hare population to begin to rebound or recover and the cycle continues. What Else is Going On? In the perfect world we would see this ideal population cycle, however there is always more to the story. Read the case study and determine what other factors may impact the populations.

  19. Consolidation – Analyze This! • Look at the graph and determine the following: • Carrying capacity • Limiting factors • Trends • Anomalies What is going on in this population of Canadian Cod?

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