Download 8th Grade Science

8th Grade Science
Lecture 6
Environmental Impact Over Time
Ozgur Unal
8th Grade Science
Lesson Objectives:
1)Explain how living and nonliving environmental factors
impact evolution.
2)Describe how natural selection occurs in a species.
3)Compare and contrast selective breeding and natural
selection.
Survival and the Environment
Would you be more likely to see a polar bear or a
monkey where you live?
Living and non-living factors influence the survival of a
species.
Species and the Environment
How come so many species came to exist on Earth?
Charles Darwin and Alfred R Wallace separately
concluded that different, long term, environmental
influences on populations produced the variety of species.
What does this mean?
Natural Selection
According to Darwin and Wallace, changes happen from
generation to generation.
These changes result in adaptation to environment 
evolution
Evolution is the change in the genetics of a species over
time.
How does evolution take place in nature?
Darwin’s theory of evolution explains this
by natural selection.
Natural Selection
Darwin and Wallace proposed that organisms that are
better adapted to an environment survive and reproduce
at a greater rate than organisms that are not.
This is called natural selection.
Check out Figure 14!!
Mutation
A change in genotype might change the phenotype.
Mutation is the process in which DNA changes result in
new alleles.
Not all mutations are good for survival!
Selective Breeding
Certain types of animals and plants are carefully bred by
humans for benefits.
Direction of Evolution
Revisit Figure 14!!
The production of several species from one ancestral
species is called adaptive radiation.
Extinction of Species
Do dinosaurs exist today?
Extinction occurs when the last individual of a species
die.
Not only dinosaurs, millions of species became extinct
throughout the history of Earth.
What are the reasons for extinction?
Check out Figure 16!!