Download 2. Abiotic Factors influence natural selection

You have researched the different theories of evolution….
• Scientists view on evolution has changed over the
years. We currently use Darwin’s theory because it is
best supported by current science.
• Evolution is called a theory because our view is
static- it is constantly being modified based on new
information we learn through science.
There are two divisions in the theory of evolution….
•Microevolution is accepted by most- it is based on the
theory of natural selection- where the most fit organisms
survive and pass their traits to their offspring.
•Macroevolution is the more controversial. It involves
organisms evolving into new species.
1.
All organisms have the ability to produce more offspring than can survive.
• Natural Selection is a “check” to control overpopulation, so
organisms that are less fit will not survive.
those
1.
Organisms produce more offspring than can survive:
•
Less fit offspring will not survive
2.
Abiotic Factors affect Natural Selection:
•
Limiting Factors (resources that can run out eventually) affect what
organisms can live in an area…
•
Natural selection is affected by this, more fit organisms
survive those conditions and reproduce while the others die from a lack of
that resource.
•
Competition for the resources affects the number of organisms that can
survive.
1.
Organisms produce more offspring than can survive:
•
2.
Less fit offspring will not survive
Abiotic Factors influence natural selection:
•
Limiting factors determine what organisms can survive.
•
Organisms that can out-compete for resources will survive and
pass on their traits (survival of the fittest)
3.
Individuals differ in their traits genetically.
•
Genetic variations influence natural selection.
•
New variations are caused by genetic mutations.
•
Genetic mutations either positively or negatively influence natural
selection.
•
Changes that cause evolution are ALWAYS inherited…they never occur
within one organisms’ lifetime.
1.
Organisms produce more offspring than can survive:
•
2.
Abiotic Factors influence natural selection:
•
3.
Less fit offspring will not survive
Limiting factors determine what organisms can survive.
Traits vary based on an individual’s genetics
•
Mutations cause variation- if it helps the organism they survive
and pass the trait on to their offspring; variations are always
inherited
4.
Some traits give individuals advantages over their current environment.
•
They help them survive against environmental challenges
•
They allow them to produce more offspring
•
These traits are “naturally selected”
•
They are determined by the SELECTIVE AGENT= the biotic or abiotic
factor that is choosing what type of species survives and what
species dies
Example: peppered moth was selected by birds that could see them
against the trees.
2.
Abiotic Factors influence natural selection:
•
3.
Traits vary based on an individual’s genetics
•
4.
Limiting factors determine what organisms can survive.
Mutations cause variation; variations are always inherited
Organisms with traits that are better adapted to the environment
survive and pass them on to offspring
•
Selective agents determines the traits that are most fit.
example: the limiting resource
5.
Natural selection causes evolution to occur:
•
Offspring with the better adaptations tend to have more offspring, which
in turn have more offspring…
•
Over many generations, the adaptation becomes standard= evolution
4.
Organisms have traits that are better adapted to the environment
•
Selective agents choose the traits that are most fit.
5.
Natural selection causes evolution
•
Better traits are passed along from generation to generation. When most
of the population has that trait the species has evolved.