Struggle for Existence&Natural SelectionStruggle for Existence&Natural Selection
Struggling to LiveStruggling to Live
Thomas Malthus – There are limits to the sizes ofpopulations
Going to run out of SOME resource
Food, water, room, etc…
“Struggle for”
More individuals produced than can survive
Struggle for ExistenceStruggle for Existence
Not
everyone
gets
to
live
&
reproduce
Natural Natural
SelectionSelection
Instead
of
humans
selecting
(artificial
selection)
which
animals
will
breed,
NATURE
will
select
Weakest
(least
“fit”
to
survive)
do
not
survive
and
cannot
reproduce
Adaptations – any inherited characteristics thatincrease 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.
Natural SelectionNatural Selection
Nature does the same thing as artificialselection
Individuals are “allowed” to breed bysurviving
(As you can seehere, not allcompetition isbetweenpredator vs. prey)
This is theonly onethat will getto survive &breed!This is theonly onethat will getto survive &breed!
This is theonly onethat will getto survive &breed!This is theonly onethat will getto survive &breed!
It is a type of evolution that cannot be seen inshort periods of time but over LONG periods oftime.
Called “microevolution”
Proposed by Darwin
What does it mean?
First off it implies all living organisms are related
Example: tigers, panthers, and cheetahs all share a commonancestor WAY back in the day.
It means that every species is a result of descending withchanges from another species over time
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 forthe test!!
Species or animalthat uses thisadaptation
What is thisadaptation usedfor?
Adaptations
Boa Constrictor
Ants
Tiger