Tues. 2/25
• Collect: Guided Reading-Ch 17
• Today: Quiz-Ch 17, Notes-ch 19, What if
Anything Reading.
• Homework: Guided Reading-ch 19
• Next class: Essay-Ch 17-19
Pg. 136
Guided Reading-Ch 19
Pg. 137
EK Paragraph-Ch 19
EK 1B2
In: pg 138
Watch Bozeman video on Phylogenetics
and write down 5 facts.
Pg 139
Chapter 19-Taxonomy,
Systematics and Phylogeny
The naming of species
Linneas-developed classification system based on
morphology.
• Binomial nomenclature (genus species)
– Homo sapien
• H. sapien
– Homo neanderthalensis
• H. neanderthalensis
Subspecies concept:
Homo sapien sapien
Homo sapien neanderthalensis
• There are 1.4 million identified and named species—it is
estimated that there are 5-10 million species on earth
Systems of Classification
6 kingdom system
• Hierarchal
classificationgroups organisms
at different levelstaxa.
Evolution of taxonomic systems
Linnaeus-animalia and
vegetabilia
1960’s-5 kingdom system
Monera (bacteria), protista,
fungi, plantae and
animalia
1980’s-6 kingdom systemeubacteria,
archeabacteria, protista,
fungi, plantae and
animalia
An emphasis in genetics led
to the 3 domain system.
• Currently, many
textbooks from the United
States use a system of
six kingdoms (Animalia,
Plantae, Fungi, Protista,
Archaea, and
Eubacteria), while British
and Australian textbooks
describe five kingdoms
(Animalia, Plantae, Fungi,
Protista, and Prokaryota
or Monera).
The domain system
Phylogeny
Phylogeny is the evolutionary
history of a species
• Common ancestor is base of
tree.
• Each lineage(branch)
represents a descendent that
diverged.
How to determine phylogenies
1. Ancestral traits-traits that all
members of the ―tree‖ share
with the common ancestor.
2. Derived traits-traits not
found in the common
ancestor.
– Shared derived traits-when 2
descendent species share a trait
not found in the ancestror
– Helps to group organisms in the
phylogeny.
Cladistics
• Cladistics-uses shared,derived traits to
show evolutionary relationships.
• Cladogram shows these relationships and
consists of clades(ancestor and all its
descendant lineages).
• Uses out groups (the one group that
doesn’t possess the trait) to determine in
groups(the organisms that do possess the
trait)
Parsimony
• Simplest solution is the best solution.
• Cladogram with the fewest evolutionary
changes is the most acceptable.
– Hypothesis about evolutionary relationships
A Cladogram
Methods for Establishing
Phylogenic relationships
•
•
•
•
Fossils-morphological
DNA-nucleotide comparison
Behavioral traits-mating calls, care for young.
Protein comparisons-the more similar organisms are, the
more similar their proteins.
• Molecular clock-genes evolve at a similar rate.
– The number of differences is a measure of time since
common ancestor.
Analogy vs. Homology
Sorting homology vs.
analogy...
• Homology-likenesses
attributed to common
ancestry
– Results from
divergent evolution
• Analogy-likenesses
attributed to similar
ecological roles and
natural selection.
– Results from
convergent
evolution
Pg. 140
Model of a Molecular
Clock
Pg. 141
What if Anything Is a
Zebra Questions.
Out
Write a paragraph briefly decribing how
molecular traits can be used to develop
phylogenies. How do you think computers
help with this?
Thurs. 2/27
• Collect: Guided Reading-Ch 19, Tape in-What if Anything is a Zebra?
Questions(not collected).
• Today: Essay, Making Cladograms
• Homework: Finish Making Cladograms, ,
Making a Model of a Molecular Clock
• Next class: Quiz-Ch 19, Cladogram Lab.
Phylogenetic tree
based on
Cytochrome-C
differences
A
• Cytochrome c is an ancient molecule, and it has evolved very
slowly. Even after more than 2 billion years, one-third of its
amino acids are unchanged. This conservatism is a great help
in working out the evolutionary relationships between distantlyrelated creatures like fish and humans.
• But what of humans and the great apes? Their cytochrome c
molecules are identical and can tell us nothing about
evolutionary relationships.
• However, some proteins have evolved much more rapidly than
cytochrome c, and these can be used to decipher recent
evolutionary events. During blood clotting, short peptides are
cut from fibrinogen converting it into insoluble fibrin. Once
removed, these fibrinopeptides have no further function. They
have been pretty much free from the rigors of natural selection
and have, consequently, diverged rapidly during evolution. So
they provide data useful in sorting out the twigs of phylogenetic
trees of mammals, for example.
Sequence of amino acids in
cytochrome c
1
6
10
14
17 18
20
Human Gly Asp Val Glu Lys Gly Lys Lys Ile Phe Ile Met Lys Cys Ser Gln Cys His Thr Val Glu Lys
Pig
-
-
-
-
-
-
-
-
-
- Val Gln -
- Ala -
-
-
-
-
-
-
Chicken
-
-
Ile
-
-
-
-
-
-
- Val Gln -
-
-
-
-
-
-
-
-
Dogfish
-
-
-
-
-
-
-
- Val - Val Gln -
- Ala -
-
-
-
-
- Asn
Drosophil
a
-
-
-
-
-
-
- Leu
Ala -
-
-
-
-
- Ala
- Ala -
-
-
-
- Asp Ala
- Ala Thr Leu - Lys Thr Arg - Glu Leu -
-
-
-
Wheat
- Asn Pro Asp Ala - Ala -
Yeast
- Ser Ala Lys -
-
Val Gln Arg
- Lys Thr -
-
-
-
In: pg. 142
Cytochrome-c Tree Questions- use the diagram to
answer the questions.
1. What type of molecule is Cytochrome C?
2. What is represented by ―A‖ on the tree?
3. Which group of organisms shares the least
similarities in Cytochrome C with humans?
4. Which species is most closely related to the
penguin?
5. In what situation is Cytochrome-c useless to
determine phylogenies?
6. In what situation would a faster evolving protein be
more useful?
Pg 143
Making a Cladogram Activity
• Tape in after you get it back corrected.
Out
What are the benefits and drawbacks of a
cladogram based on morphological
similarities? Defend your answer.
Mon. 3/2
• Collect: Making a Cladogram
• Today: Quiz-Ch 19, Grade Essays,
Cladogram Lab-Due next class and put
into Lab Binder when returned.
• Homework: Finish Cladogram Lab.
• Next class: Test and INB Check