Transcript Bio 134, Chapter 15 Notes (Evolution)

Ch. 15 Evolution
p. 418 - 441
15.1 Darwin’s Theory of
Natural Selection
p. 418 – 422
Main Idea
Charles Darwin developed a theory of
evolution based on natural selection.
What was the primary mission of
the Beagle?
To survey the coast of South America
What did Darwin make
collections of?
Rocks, fossils, plants and animals
What did Darwin notice as he
made collections of the animals
in the Galapagos Islands?
He noticed that the different islands seemed
to have their own, slightly different varieties
of animals
What are two examples of when
artifical selection occurs?
When breeding dogs
When new strains of crops
What was interesting about
almost every specimen that
Darwin collected in the
Galapagos?
It was new to European scientists
What did Darwin hypothesize?
New species could appear gradually through
small changes in ancestrial species
What did Darwin reason from the
economist Malthus’ ideas?
That some competitors in the struggle for
existence would be better equipped for
survival than others
Those less equipped would die
What are the four basic principles
of Darwin’s theory?
1. Individuals in a population show
differences, or variances
2. Variations can be inherited
3. Organisms have more offspring than can
survive on available resources
4. Variations that increase reproductive
success will have a greater chance of being
passed on
Visualizing Natural Selection:
give an example of how a sunflower population
exhibits the for principles of natural selection
Variation – some sunflowers are taller than others
Heritability – tall sunflowers produce tall
sunflowers; short sunflowers produce short
sunflowers
Overproduction – each sunflower has hundreds of
seeds, most of them will not germinate
Reproductive advantage – shorter sunflowers
reproduce more successfully
Evolution
Cumulative changes in groups of organisms
through time
How does the term evolution
relate to natural selection?
Natural selection is a means of explaining
how evolution works
15.2 Evidence of Evolution
p. 423-430
Main Idea
Multiple lines of evidence support the
theory of evolution
What did On the Origin of
Species demonstrate?
How natural selection might operate
What also did it provide?
Evidence that evolution has occurred on our
planet
What does a theory explain?
How some aspect of the natural world
operates
What does the theory of
evolution state?
It states that all organisms on Earth have
descended from a common ancestor.
What do fossils provide?
A record of species that lived long ago
Why is the fossil record
important?
It is an important source of information for
determining the ancestry of organism and
the patterns of evolution.
What is a transitional fossil?
A fossil that contain features shared by
different species
Derived trait
Newly evolved features, such as feathers,
that do not appear in the fossils of common
ancestors
Ancestral trait
More primitive features, such as teeth and
tails, that do appear in ancestral forms
Homologous structures
Anatomically similar structures inherited
from a common ancestor
Give an example of homologous
structures
Bird wings and reptile limbs
They are similar shape and construction,
indicating that they were inherited from a
common ancestor
Vestigial structures
Structures that are reduced forms of
functional structures in other organisms
Give an example of vestigial
structures:
Snake pelvis – attachment point for legs and
is non functional in animal without legs
Kiwi wings – too small to be of any use in
flight
Human appendix – important in many
mammals, but of limited use in humans and
some apes
Embryo
An early, pre-birth stage of an organism’s
development
Biogeography
Study of the distribution of plants and
animals around the world
What are the 5 topics that offer
evidence for evolution:
1.
2.
3.
4.
5.
Fossil record
Comparative anatomy
Comparative embryology
Comparative biochemistry
Geographical distribution
What is an adaptation?
A trait shaped by natural selection that
increases an organism’s reproductive
success.
Fitness
A measure of the relative contribution an
individual trait makes to the next
generation.
The better an organism is adapted to its
environment, the greater its chances of
survival and reproductive success.
Camouflauge
Morphological (form & structure) adaptations
that allow them to blend in with their
environments
Mimicry
A morphological adaptation where one
species evolves to resemble another species