Download The Theory of Evolution

The Theory of Evolution
What is the Theory of
Evolution?

Theory: well-supported testable
explanation of phenomena that have
occurred in the natural world

Evolution: change over time; process by
which modern organisms have descended
from ancient organisms
Who is Darwin?

Charles Darwin is
considered the father of
modern evolutionary theory

Darwin’s 5 year voyage as
the naturalist on the HMS
Beagle helped him develop
the theory of how evolution
occurs
Figure 15–1 Darwin’s Voyage
Section 15-1
Darwin Presents His Case
Through his observations on the
Galapagos Islands, he concluded that
natural variation or differences occur
among individuals of a population
 Scientists later found out that these
variations among individuals were caused
by mutations

Natural Selection
(Darwin’s main point)

Organisms with more favorable traits or
variations tend to survive and reproduce;
organisms with less favorable traits are
less likely to survive
2 Main Points of Natural Selection
1.
Struggle for existence: competition for
territory, food, water, and mates
2.
Survival of the fittest: some organisms
are better suited to survive in an
environment as a result of adaptations
(mimicry or camouflage)
Evidence for Evolution
1.
Fossils: by using fossils,
scientists can show the
sequence of evolution in
an organism
Beaver
Muskrat
Beaver and
Muskrat
Coypu
Capybara
2.
Geography: organisms
that are similar but live
in different parts of the
world
Coypu and
Capybara
Evidence for Evolution
3.
Homologous
Structures:
structures that are
similar and seen in
different species
•
Ex: forelimbs of
humans/bats
Evidence for Evolution
4.
Embryology: by studying unborn
organisms, we can see structures in
common during development in different
organisms
Embryology
5.
Genetic Relationships: DNA comparisons
help establish evolutionary relationships
between different species