Download Evolutionary Classification Notes (17.2)

Evolutionary Classification (17.2)
State Standard
SB3C. Examine the evolutionary basis of
modern classification systems.
Chapter 17
Organizing Life’s Diversity
17.2 Modern Classification
Phylogenetic Species Concept
 Phylogeny is the evolutionary history of a
species.
 The phylogenetic species concept defines a
species as a cluster of organisms that is
distinct from other clusters and shows
evidence of a pattern of ancestry and
descent.
 It also takes into account DNA similarities.
Chapter 17
Organizing Life’s Diversity
17.2 Modern Classification
Characters
 To classify a species, scientists construct
patterns of descent by using characters.
 Characters can be morphological or
biochemical.
Chapter 17
Organizing Life’s Diversity
17.2 Modern Classification
Morphological Characters
 Shared morphological characters suggest that
species are related closely and evolved from a
recent common ancestor. Ex. Hawks & Eagles
 Analogous characters are those that have the
same function but different underlying
construction. No indication of common ancestry
 Homologous characters might perform different
functions, but show an anatomical similarity
inherited from a common ancestor.
Chapter 17
Organizing Life’s Diversity
17.2 Modern Classification
Homologous Structures
Between
Birds and Dinosaurs
 Hollow bones
Haliaeetus leucocephalus
 Theropods have leg,
wrist, hip, and shoulder
structures similar to birds.
 Some theropods may
have had feathers.
Oviraptor philoceratops
Chapter 17
Organizing Life’s Diversity
17.2 Modern Classification
Biochemical Characters
 Scientists use biochemical characters, such
as amino acids and nucleotides, to help
them determine evolutionary relationships
among species.
 Chromosome structure & number is a
powerful clue for determining species
similarities.
 DNA and RNA analyses are powerful tools for
reconstructing phylogenies.
Chapter 17
Organizing Life’s Diversity
17.2 Modern Classification
 The similar appearance of chromosomes among
chimpanzees,
gorillas, and
orangutans
suggests a
shared
ancestry.
Chapter 17
Organizing Life’s Diversity
17.2 Modern Classification
Molecular Clocks
 Scientists use molecular
clocks to compare the DNA
sequences or amino acid
sequences of genes that
are shared by different
species.
Chapter 17
Organizing Life’s Diversity
17.2 Modern Classification
 The differences between
the genes indicate the
presence of mutations.
 The more mutations that
have accumulated, the
more time that has
passed since divergence
of the species from the
common ancestor.
Chapter 17
Organizing Life’s Diversity
Chapter Assessment
Questions
What does this image represent?
A. phylogeny of species
B. molecular clock
C. cladogram
D. tree of life
0%
D
0%
C
0%
B
A
0%
1.
2.
3.
4.
A
B
C
D
Chapter 17
Organizing Life’s Diversity
Chapter Assessment
Questions
What do the colored bands in the
figure represent?
A. mutations
B. molecular clock
C. time
D. gene
1.
2.
3.
4.
0%
D
0%
C
0%
B
A
0%
A
B
C
D
Chapter 17
Organizing Life’s Diversity
Standardized Test
Practice
Which pair of organisms is more closely
related?
1.
2.
3.
A
0%
0%
B
A. 1 and 2
B. 2 and 3
C. 1 and 3
A
B
C
0%
C
1. Quercus alba
2. Cornus alba
3. Quercus rubra
Chapter 17
Organizing Life’s Diversity
Standardized Test
Practice
How do systematists use this model
to determine the degree of relationship
among species?
A
B
C
D
0%
0%
D
0%
C
0%
B
1.
2.
3.
4.
A
A. It shows the chromosomal
structure of different species.
B. It shows the genetic makeup
of a common ancestor.
C. It shows the rate of mutation
for different species.
D. It shows the relative time of
divergence of a species.
Chapter 17
Organizing Life’s Diversity
Vocabulary
Section 2
phylogeny
character
molecular clock
cladistics
cladogram