Darwin’s Theory of
Evolution
Chapter 16
Section 16.1 Darwin’s Voyage
Objectives:
State Darwin’s contribution to science
Describe the biodiversity Darwin
observed
Video clip
Evolution:
Evolution: change in species over time
Charles Darwin
Born in England on Feb. 12, 1809
Naturalist who studied diversity of life
Took 5 year trip on HMS Beagle (1831-36)
Darwin’s Observations
Species vary globally
Rhea
S. America
Ostrich
Africa
Emu
Australia
Darwin’s Observations
Species vary locally
Hood
Island
Tortoise
Isabela
Island
Tortoise
Darwin’s Observations
Species vary over time
Fossil: preserved remains or traces of
ancient organisms
Related??
Check-in
What is evolution?
Change in species over time
Contrast the pattern Darwin observed
among the large, flightless birds and
the pattern he observed among the
tortoises.
Similar environments seem to result in
similarities among organisms. Different
environments result in differences among
organisms.
Section 16.3 Darwin’s Ideas
Objectives:
Describe conditions under which natural
selection occurs.
Explain common descent.
Evolution by Natural Selection
Struggle for Existence
Not all young survive
Some killed by disease, predators
Only some reproduce
Evolution by Natural Selection
Variation and Adaptation
Natural differences among same species
Adaptation: heritable variation that
increases change of surviving and
reproducing
Evolution by Natural Selection
Survival of the fittest
Fitness: how well an organism can
survive and reproduce
Organisms with favorable traits survive
and reproduce
Offspring inherit
those traits/genes
Evolution by Natural Selection
Natural Selection occurs when
More individuals are born than can survive
There is natural heritable variation
There is variable fitness among individuals
Principle of Common Descent
Descent with
modification
“All species – living and
extinct – descended
from ancient common
ancestors”
Check-in
Describe the expected evolutionary
change of these rabbits over time.
Include the conditions under which
natural selection occurs.
Section 16.4
Evidence of Evolution
Objectives:
Describe various types of evidence to
support evolution.
Evidence of Evolution
Biogeography
Closely related but
different
Distantly related but similar
Evidence of Evolution
Age of Earth
Radioactive dating indicates Earth is
about 4.5 billion years old
Fossils
Trace evolution of
modern species from
extinct ancestors
Evidence of Evolution
Anatomical Structures
Homologous: similar structures inherited
from common ancestor
EX. Similar arm and hand bones in human,
cat, whale, bat
Evidence of Evolution
Anatomical Structures
Analogous: similar function, but different
structure (and different ancestor)
EX. Wings of bird vs. wings of butterfly
Evidence of Evolution
Anatomical Structures
Vestigal: reduced in size and function
EX. Pelvic bones in whale; appendix in
humans
Evidence of Evolution
Embryology
Similarities in fetal development
Evidence of Evolution
Biochemistry / DNA
Similar DNA patterns
98% similarity between humans and chimps
90% similarity between human and mouse
Similarities in the chemical compounds
that make up organisms
Ex. Cytochrome C used in cellular
respiration is similar in almost all living cells
Check-in
List some things that provide
evidence to support the theory of
evolution.
Biogeography, age of Earth, fossils,
anatomical structures, embryology,
biochemistry/DNA
Give an example of biogeography in
which species are closely related but
different. Finches, tortoises
Check-in
What type of structure is each of the
following an example of:
Wings of bird and wings of bee
Analogous structure
Human appendix Vestigal structure
Wing of chicken and foreleg of alligator
Homologous structure