Struggle for Existence

1
Struggle for Existence Natural Selection
2
Struggling to Live

• Thomas Malthus There are limits to the sizes of
  populations
• Going to run out of SOME resource
• Food, water, room, etc
• Struggle for
• More individuals produced than can survive

Existence
3
Struggle for Existence

• Not everyone gets to live reproduce
• Natural Selection
• Instead of humans selecting (artificial
  selection) which animals will breed, NATURE will
  select
• Weakest (least fit to survive) do not survive
  and cannot reproduce

Survival of the fittest
4
Fitness and Adaptations

• Adaptations any inherited characteristics that
  increase an organisms chance for survival.
• Can be
• Anatomical (structural) ex a porcupines quills
• Physiological processes ex plants can do
  photosynthesis
• Behavioral this is the most complex. Ex
  animals hunting in groups.

5
Natural Selection

• Nature does the same thing as artificial
  selection
• Individuals are allowed to breed by surviving
• (As you can see here, not all competition is
  between predator vs. prey)

6
Facts About Natural Selection

• It is a type of evolution that cannot be seen in
  short periods of time but over LONG periods of
  time.
• Called microevolution

7
Descent with Modification

• Proposed by Darwin
• What does it mean?
• First off it implies all living organisms are
  related
• Example tigers, panthers, and cheetahs all share
  a common ancestor WAY back in the day.
• It means that every species is a result of
  descending with changes from another species over
  time

8
Its a Jungle Out There!

• How species are adapted to survive in the jungle
• In your notes, make a chart similar to this one.
  Take GOOD NOTES you will want to know these for
  the test!!

Species or animal that uses this adaptation What is this adaptation used for? Adaptations
Boa Constrictor
Ants
Tiger
9

• It's A Jungle Out There! PBS Clips