From Darwin

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From Darwins collection of evidence he created
his theory of evolution by NATURAL SELECTION
(sometimes referred to as the survival of the
fittest).
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This theory is based on six points

• 1. Overproduction
• More offspring are produced than can survive.
• Examples Fish that lay millions of eggs, Sea
  turtles.
• Based this belief on Thomas Malthus s writings
  on population survival.

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Example of overproduction
Sea Turtles - lay from 70 to 190 eggs (depending
on the species). Only about 1 out of 100 survive.
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• 2. Competition
• Because of overpopulation, organisms of the same
  species, as well as those of different species,
  must compete for limited resources such as food,
  water, and a place to live.
• Interspecific competition between different
  species
• Intraspecific competition between the same
  species

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• 3. Variation
• Differences occur among members of the same
  species. No two individuals are exactly alike.
• These variations are passed onto the next
  generation.

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• 4. Survival of the Fittest
• Natural selection.
• Individuals in a species with traits that give
  them an advantage are better able to compete,
  survive and reproduce. Others die off without
  leaving offspring.

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• 5. Speciation
• Origin of new species.
• Over numerous generations, new species arise by
  the accumulation of inherited variations.
• When a type is produced that is significantly
  different from the original, it becomes a
  species.
• A species can reproduce successfully with its own
  kind.

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• 6. Adaptation
• The accumulation of characteristics that improve
  a species ability to survive over long periods
  of time.
• Allows organisms to become better suited to their
  environment.

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Adaptations

• There are 3 broad categories of adaptations
• Physiological
• Behavioural
• Structural

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1. Physiological

• Physiological adaptations involve what is going
  on inside the body.
• Example - hibernation of bears.
• - cows ruminant digestive system.
• - pesticide-resistant insects.
• - antibiotic resistant bacteria.

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2. Behavioural

• An organisms behaviour may provide it with a
  better chance of surviving and reproducing.
• Example - Storage of nuts by squirrels.
• - Plants bending towards light.
• - Animals playing dead.
• - migration of Canada geese.

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• Staying in the shade is a behavioural adaptation
  common in nature.

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3. Structural

• Structural adaptations involve an organisms
  anatomy.
• Examples - Webbed feet of ducks for
  swimming.
• - talons on eagles for grasping.
• - Camouflage. This can be used to benefit both
  predator and prey.
• - Mimicry.

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Angler Fish
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• Example of camouflage - Phasmatodea (walking
  stick insect)

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• Example of mimicry - moth resembles owl
• to scare off predators.

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• Adaptations do not always fit neatly into just
  one of these categories. They may be in
  combination.
• Example
• Elephants ear.

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• Advantageous adaptations give an organism a
  competitive edge in the struggle for food, space,
  ability to reproduce and the ability to avoid
  predators.
• Habitats also change, so what was once an
  advantage may one day become a disadvantage.
• Successful (the fittest) organisms are the ones
  with adaptations that allow them to survive and
  to reproduce.

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Do not confuse adaptation with

• Acclimatization when an organism becomes
  accustomed to changing environmental conditions.
  It is not the product of natural selection.
  There is no change in the gene pool of the
  species.
• Example getting used to cold weather in winter.