Download Notes: Chapter 15 Darwin`s Theory of Evolution

Chapter 15 Notes: Darwin’s Theory of Evolution
Section 15-1 Darwin’s Journey
I. Theory of Evolution – change in living things over time;
process by which modern organisms have descended from
ancient organisms
A. Theory – a well-supported and testable explanation
II. Darwin’s Voyage
A. Charles Darwin – contributed more to our understanding of
evolution than anyone else
a. born in England 1809
b. Darwin traveled around the world and collected
evidence that led him theory of evolution
B. Darwin’s observations
a. Darwin’s thoughts:
1. an enormous amount of species populate the
Earth
2. each organism is suited to their environment
3. found fossils of some organisms that do not
exist any more and wondered why
b. Darwin’s studies at the Galapagos Islands
1. small group of islands; close together, but
have different climates
2. found that animals on different islands had
slightly different characteristics, but seemed to
be related
3. Darwin wondered if the different animals
once belonged to the same species
Section 15-2 Ideas that Shaped Darwin’s Thinking
I. Scientists that contributed to Darwin’s theory:
A. 1785 Hutton: Earth is shaped by geological forces over a long
period of time
B. 1798 Malthus: if the human population continues to grow, there
will not be enough space and food
C. 1809 Lamarck: first to propose an explanation of how things
change over time; was not correct!!
D. 1831 Darwin: sets sail on the “H.M.S.Beagle” and collected
evidence
E. 1833 Lyell: processes occuring now have shaped the Earth
F. 1858 Wallace: Writes to Darwin about Natural Selection
G. 1859 Darwin publishes his book “On The Origin of the
Species”
Section 15-3 Darwin’s Book
I. Inherited Variation – members of a species are all different
II. Artificial Selection – humans can select the variations of organisms
that are useful and breed these individuals
A. example: breeding cows that produce the most milk
III. Natural Selection – traits that allow an organism to survive will
increase over time, and traits that do not allow an organism to survive
will decrease over time
A. All organisms struggle to survive
B. Fitness - the ability of an organism to survive and reproduce
C. Adaptation – an inherited trait that increases an organism’s
chance of
survival ex: an insect that looks like a leaf can’t be seen by predators
D. “Survival of the fittest”
E. Natural selection is how evolution occurs
F. Natural selection results in changes in the inherited
traits of a population
G. Cannot be seen directly – takes place over many generations
over a long period of time
IV. Descent with modification – natural selection produces organisms
that have different structures or live in different places
As a result, species today look different from their ancestors
V. Common Descent – all species – living and extinct – came from one
common ancestor; “tree of life”
VI. Evidence of Evolution
A. Fossil record – shows gradual changes over time
B. Geographic distribution – different locations (environments)
may cause a variety of changes in organisms over time; similarlooking animals in different locations may or may not be from a
common ancestor
C. Homologous structures – organisms with similar body
structures share a common ancestor
ex: limbs of vertebrates
D. Vestigial structures – a structure with no function
ex: human appendix (no function in digestion)
E. Similar embryo stages – development of vertebrates is very
similar