Download Lecture Ch 7

Table of Contents
Chapter
Preview
7.1 Darwin’s
Theory
7.2 Evidence of
Evolution
7.3 Evolution of
Species
7.4 Classifying
Organisms
7.5 Branching
Trees
Chapter 7 Preview Questions
1. Compared to body cells, the cells that
result from meiosis have
a. half the number of chromosomes.
b. the same number of chromosomes.
c. double the number of chromosomes.
d. triple the number of chromosomes.
Chapter 7 Preview Questions
1. Compared to body cells, the cells that
result from meiosis have
a. half the number of chromosomes.
b. the same number of chromosomes.
c. double the number of chromosomes.
d. triple the number of chromosomes.
Chapter 7 Preview Questions
2. Which is true of the alleles for a gene?
a. There are only two alleles for every
gene.
b. The alleles are always identical.
c. The alleles are never identical.
d. One allele may be dominant.
Chapter 7 Preview Questions
2. Which is true of the alleles for a gene?
a. There are only two alleles for every
gene.
b. The alleles are always identical.
c. The alleles are never identical.
d. One allele may be dominant.
Chapter Preview Questions
3. An organism’s traits are determined by its
a. carbohydrates.
b. DNA.
c. mitochondria.
d. chloroplasts.
Chapter Preview Questions
3. An organism’s traits are determined by its
a. carbohydrates.
b. DNA.
c. mitochondria.
d. chloroplasts.
Chapter 7 Preview Questions
4. Where do sexually reproducing organisms
inherit their alleles from?
a. half from each parent
b. mostly from their mother
c. mostly from their father
d. only from their mother
Chapter 7 Preview Questions
4. Where do sexually reproducing organisms
inherit their alleles from?
a. half from each parent
b. mostly from their mother
c. mostly from their father
d. only from their mother
Changes Over Time
Section 7.1:
Darwin’s Theory
What important observations did Darwin
make on his voyage?
How did Darwin account for the
diversity of species and the differences
between similar species?
How does natural selection lead to
evolution?
CHARLES DARWIN
Changes Over Time
Darwin’s Voyage
•Charles Darwin sailed on the HMS
Beagle --1831
•England to the Galápagos Islands.
•He was the ships naturalist
•5 years
Darwin's Discoveries
Finches had beaks
adapted to their diet
Mainland Iguanas had
short claws
Those on the islands had
long claws
The Galapagos cormorant had
lost its ability to fly
The shells of the tortoise
differed between the islands.
The Theory of Natural
Selection
In 1859 ----Darwin proposed his
theory of evolution based on the
idea of natural selection.
Natural Selection= the strongest
or most fit survive
Changes Over Time
Overproduction and Variation
Overproduction is when an organism
produces too many offspring to
increase the chance of survival .
Overproduction and Variation
Variation is when offspring have
differences .
Each individual that is born will
have different characteristics.
These characteristics are heritable
Changes Over Time
Competition and Selection
Variations among animals can give
them traits that can help them survive
and reproduce.
Section 7.2:
Evidence of
Evolution
What evidence supports the theory of
evolution?
How do fossils form?
What do scientists learn from fossils?
Homologous Structures
Homology is when bones are
similar in different organisms.
HOMOLOGOUS STRUCTURES
Homologous structures are
one piece of evidence
scientists use to prove
evolution
FOSSILES
ARCHIOPTERIX- the first bird
TRILOBITES
Index fossils that were
alive a short time
How Do Fossils Form?
Most fossils form when
organisms that die become
buried in sediments.
Changes Over Time
The fossils record
provides evidence
about …
•past live forms
• past environment.
• rate at which
evolution occurred
Section 7.3:
Evolution of
Species
What factors have contributed to the
diversity of species?
How do new species form?
How do scientists infer evolutionary
relationships among species?
What causes the extinction of species?
Kaibab and Albert's
Squirrels
These two kinds of
squirrels have been
isolated from one
another for a long time.
Isolation may
result in two
different
species.
A Branching Tree
This branching tree shows how scientists
now think that raccoons, lesser pandas, giant
pandas, and bears are related.
Extinction of Species
Extinction is
caused by a
change in
species'
environment.
Section 7.4:
Classifying Organisms
Why do biologists organize living things
into groups?
What do the levels of classification
indicate about the relationship between
organisms?
What characteristics are used to
classify organisms into domains and
kingdoms?
Levels of Classification
As you move down the levels of
classification, the number of organisms
decreases. The organisms at lower levels
share more characteristics with each other.
Three Domains of Life
In the three-domain system
of classifications, all known
organisms belong to one of
three domains–Bacteria,
Archaea, or Eukarya.
Bacteria
Archaea
Eukarya
Protists Fungi
Plants
Animals
Bacteria
Single celled
No nucleus
prokaryotes
Archaea
Single celled
No nucleus
Prokaryotes
Ancient
Eukarya.
Have a nucleus
Third domain
The kingdoms
Section 5:
Branching Trees
How does a branching tree
diagram show evolutionary
relationships?
A Branching Tree
Branching trees show
relationships between groups
of organisms.
It also shows the order in
which specific characteristics
may have evolved.
Shared Derived Characteristics
A branching tree diagram shows evolutionary
relationships by grouping organisms
according to shared derived characteristics.
Amphibia
ns
Fishes
Invertebrate
s
Egg with
shell
Four limbs
Backbone
Ancestor of
animals
Reptiles