Natural Selection and Adaptation

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Natural Selection and Adaptation
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Survival of the Fittest

• Natural Selection is the process by which
  individuals that are better suited to their
  environment survive and reproduce the most
  successfully

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• Natural Selection is the mechanism by which
  evolution takes place.
• Even though natural selection can work on
  individuals, evolution examines how a population
  or species changes.

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Example of Natural Selection Pesticide Resistant
Bugs

• Imagine that in a population of insects some
  are resistant to pesticide and others are not.
  After pesticide is used, the resistant insects
  survive and are able to reproduce. Their
  offspring will be resistant to the pesticide from
  birth. Those that are not immune will die. By the
  time a few generations have passed, the
  population is likely to be resistant to the
  pesticide.

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The 5 principles of Natural Selection

1. There is genetic variation in a population
2. Some variations are more beneficial than others
   (they are adaptations)
3. More offspring are produced in a generation than
   can survive
4. Organisms that survive in their population can
   reproduce and pass on their adaptations
5. Small changes can occur within a population over
   a long period of time

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• Natural Selection takes place because genetic
  diversity exists in populations. Causes of
  genetic diversity are
• Mutations
• Crossing Over
• Independent Assortment
• Random Fertilization
• Only mutations create new traits in a population

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• An adaptation is an inherited characteristic that
  increases an organisms chance of survival.
• It is something beneficial that a species has
  evolved.
• Adaptations can come in many forms.

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Camouflage is a form of adaptation

• It is defined as concealment by some means that
  alters of obscures the appearance.

• Leopard laying the grass

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Other Examples of camouflage

• Giraffes Zebra

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Mimicry is a form of adaptation

• The close external resemblance of another
  organism or object, such that the mimic benefits
  from the mistaken identity by seeming harmful or
  hidden

• Below a planthopper mimics a leaf

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There are three main categories of adaptations

• Functional
• Structural
• Behavioral

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Structural Adaptations

• Cheetahs adapt by having muscular legs and a
  streamline body

• Modification of a body part or feature -
  describes only how the structure or form has
  changed

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Functional Adaptations

• The western clawed frog has temperature sensors
  (structural adaptation) that they use to adapt to
  their environment (functional)

• Modification of the USE of a particular body part
  or feature - describes only how a structure is
  USED.

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Behavioral Adaptations

• Modification of the inborn or instinctive
  behavior (as apposed to a learned response).

• Examples include
• Breathing
• Newborns nursing