Chapter 4 H.1.4.11 Ecological Relationship

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Chapter 4 H.1.4.11 Ecological Relationships
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Need to know

• Name factors that can control populations.
• Define and give one example of the following
  factors
• Competition
• Predation
• Parasitism
• Symbiosis

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Factors that control Population

• Competition
• Predation
• Parasitism
• Symbiosis
• These factors help maintain population numbers
  and bring about a balance of nature.

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Population

• A group of individuals of the same species living
  together in a habitat.
• They live in populations for the following
  reasons
• Their habitat provides food and shelter
• Individuals are safer in a group
• The availability of a mate for breeding purposes

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Competition

• When two or more organisms seek a resource that
  is in short supply.

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Competition for resources

• Plants
• compete for light, water, minerals and space
• Animals
• compete for food, water, shelter, territory and
  mates

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Learning check 1

• What is meant by a population?
• Why do groups of individuals of the same species
  living together in a habitat?
• Explain what is meant by competition.
• What do Plants animals compete for?

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Two types of competition

• 1. Contest Competition
• involves an active physical confrontation between
  two organisms, only one wins
• E.g. two stags fighting over mating rights

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• 2. Scramble Competition
• This is where each organism tries to acquire as
  much of the resource as possible, all get some of
  the resource.
• E.g. squirrels gather acorns

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Competition Population Size

• Restricts population size
• Only successful competitors will survive and
  reproduce
• Is a driving force behind evolution i.e. adaptive
  techniques develop in response to the need to
  survive competition.

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How do animals survive competition?

• They adapt to their environment by
• Changing their feeding habits
• Camouflage
• Producing protective coats
• Moving away from over-populated areas

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How do plants survive competition?
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How do plants survive competition?

• Dandelion weeds compete with other plants for
  water, minerals and light and will survive
  because
• They produce large numbers of seeds
• Have long tap roots which can absorb water
  minerals from deeper levels.

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Learning check 2

• Name the Two types of competition
• What effect does Competition have on Population
  Size?
• What are Adaptive techniques?
• How do animals survive competition?
• How do plants survive competition?

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2. Predation

• Predation the act, of some animals (predators),
  of capturing and killing other animals for food.
• Predator animal that hunts, captures and kills
  other animals (prey) for food.

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Adaptations of Predators

• Predators have evolved adaptive techniques to
  survive, e.g.
• keen hearing and eyesight hawks eagles,
• sharp canine teeth claws lions tigers

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Positive Effects of Predation

• Predation stabilises the community
• Predators control the number of e.g. herbivores
  and so prevent overgrazing
• Predators eliminate the less well adapted
  (weaker) prey

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Adaptations of Prey

• Plants may have thorns, spines or stings
• Camouflage greenfly, stick insects
• Ladybirds contain large amounts of Formic acid so
  they are unpalatable to taste

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Adaptations of Prey

• Adaptations of plants animals
• Goldiesroom, Biomes and Adaptations

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Learning check 3

• Explain the terms predation and predator.
• Give examples of Adaptations of Predators.
• Outline the Positive Effects of Predation.
• Give examples of Adaptations of Prey.

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Predator / Prey relationship

• The populations of wolves and deer are
  interconnected. Both have evolved adaptive
  techniques to survive
• e.g. wolves keen hearing and eyesight, strong
  muscles, sharp teeth, camouflage and hunt in
  packs.
• deer keen hearing and eyesight, quick to turn
  and run and camouflage to evade the wolves.
• YouTube - Battle for survival

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Predator / Prey relationship (Wolf / Deer in
Alaska)
Notes 1 2 3 4 5 6 7 8 9
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• Predator-prey relationships between different
  kinds of animals

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Notes on graph

• When the deer population increased, the wolf
  population had more food and increased too.
  graph
• As the wolf population increased, the number of
  deer being killed increased graph resulting in
  a decline in the deer population
• When the deer population declined, there was less
  food for the wolves and they declined in numbers
  too. graph
• This led to an increase in the deer population.
  graph

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Notes on graph

• This cycle continued over years and had obviously
  found a natural balance to do with availability
  of food for both populations. graph
• When the wolf population was drastically reduced
  due to hunting, the resulting explosion of the
  deer population led to overgrazing of the
  vegetation. graph
• This produced huge mortality and emigration in
  the deer population with a collapse of the
  relationship. graph

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Notes on graph

• After the banning of hunting, a balance was
  slowly re-established in the two populations.
  graph
• The populations are controlled by negative
  feedback, where a drop in numbers is generally
  self-correcting.
• Over a long period of time, the deer evolve
  structures and behaviours to survive predation
  better, e.g. quicker reactions, etc.
• The wolves also evolve better predation
  techniques to cope with the evolving prey.

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In Summary

• Predator/Prey relationships
• As Prey Predators .As there are more
• predators the prey will Hence predators
• Eventually numbers of prey will increase,
  starting the cycle once more.

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Graph of predator / prey relationship
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Learning check 4

• Explain what is happening at each of the numbered
  locations on this graph.

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3. Parasitism

• A parasite is an organism thats lives on or in
  another organism, called a host.
• The parasite, gains food from the host, and
  usually harms it. E.g.
• liverfluke in cattle/sheep (endoparasites live
  inside the host).
• fleas on a dog (ectoparasites live outside the
  host)
• .

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4. Symbiosis

• Symbiosis (living together) where two
  organisms of different species have a close,
  specific relationship with each other where at
  least one of them benefits.
• Mutualism both organisms benefit.
• Parasitism is a form of symbiosis

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Examples of Symbiosis

• A lichen is composed of an alga and a fungus
  intertwined. The alga obtains support and a
  mineral supply from the fungus the fungus
  obtains food from the alga.

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• Nitrogen-fixing bacteria in the nodules of
  leguminous plants (legumes) The bacteria make
  nitrogen compounds needed by the plant and the
  plant makes carbohydrates and other food material
  needed by the bacteria
• Bacteria living in the colon produce vitamin B2
  and vitamin K. The body absorbs these vitamins.

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• Community Ecology- Interspecific Interactions

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Learning check 5

• Explain the terms parasite, host, endoparasites
  ectoparasites.
• Give examples of endoparasites ectoparasites.
• Explain the term Symbiosis.
• Give an example of Symbiosis.
• Explain the term Mutualism.

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• Ecosystems Song to Jason E.

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END