SYSTEMATICS
AND
PHYLOGENY
Upon first glance, one would probably classify
this as a…________, but…
Organizing Life
• ____________________ is the branch of biology
concerned with identifying, naming, and classifying
organisms.
What are taxa?
Remember?...
Gray Wolf:
________________Eukarya,
_______________-Animalia,
_______________Chordata, ______________Mammalia,
_______________Carnivora,
_______________-Canidae,
_______________-Canus,
Some describe the groups as being “_____________________” because one group
_______________-lupus
exists within another group.
3
Species:
Panthera
pardus
Genus: Panthera
Family: Felidae
Think of your
“global” address
Order: Carnivora
Class: Mammalia
Phylum: Chordata
Kingdom: Animalia
Bacteria
Domain: Eukarya
Archaea
Taxonomy’s Binomial System
In the mid-eighteenth
century, Carolus
Linnaeus developed
the binomial system
of nomenclature to
classify organisms
First word is the __________________
The second word is the _______________
___________________: This refers to one
species (of potentially many) within its genus
A species is referred to by the full binomial name
(Genus + species)
Genus name can be used alone to refer to a group of related
species
What do the Genus and species actually specify?
5
IMPORTANT-
Why are scientific names
needed?
Lilium canadense
Lilium bulbiferum
What is the difference in
these fish?
Jellyfish
Crawfish
Silverfish
-Common names vary
both locally and
globally
-Languages vary
-Similar to the need
for the metric system
of measurements
7
Classification lists the
unique characters of
each taxon and is
intended to reflect
phylogeny, but…
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
_____________
is an analytical
branch of biology
that relies on
_____________
_____________
_____________
_____________
to determine
evolutionary
history and
relationships
–also known as
_____________
(All): © Sylvia S. Mader
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Deciphering evolutionary
history
It is often represented as a
___________________________:
A diagram indicating lines of descent
Each branching point
is a divergence from
a ______________
______________
It represents an
organism that gives
rise to two new
groups. It is also
called a ________
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Two types of
characters
used to
construct a
tree are:
_________________
characters:
Present in all members of
a group and present in the
common ancestor
(ancestral traits)
__________________characters:
Present in some members of a group,
but absent in the common ancestor
These traits “were not seen
previously”
Lancelet
Lamprey
Tuna
Salamander
Turtle
Leopard
When
inferring
evolutionary
relationships
, it is useful
to know in
which clade
a shared
derived
character
first
appeared
Order
Panthera
Felidae
ALL THESE
SPECIES
ARE
Family Genus
Species
Pantherapardus
HERE
Taxidea
Lutra
Mustelidae
Carnivora
Taxidea
taxus
Lutra lutra
THIS IS THE
Canis
Canidae
OF ALL
SPECIES
PICTURED
HERE
Canis
latrans
TAXA
Canis
lupus
Order
Family Genus
Panthera
pardus
Taxidea
Taxidea
taxus
Lutra
Mustelidae
Panthera
Felidae
Carnivora
Weakness of
basic
phylogenetic
tree:
Species
Lutra lutra
Canis
Canidae
Canis
latrans
Can’t be sure otter evolved before wolf
Canis
lupus
Also, sister taxa do not mean one came from another!
How do we know that the construction of a phylogenetic tree is
the best hypothesis of phylogeny?
studied.
Your groups will be called a
_____________________________ and
they represent a common ancestor and all
of its descendant lineages.
We’ll always need to select an
__________________________: a
species from an evolutionary heritage
that diverged before the lineage we are
studying – called the
_______________________________
___
hair
gizzard
epidermal scales
Traits
Biologists can construct
_______________________________ to
visually represent the derived
characteristics of your clade.
mammary glands
amniotic egg
four limbs
vertebrae
notochord in
embryo
lancelet (outgroup)
tuna
frog
lizard
crocodile
finch
dog
ingroup
chimpanzee
One way is through ___________________. This is a method
that uses shared and derived traits to hypothesize
evolutionary history. This will usually consider the simplest
solution, __________________________________, in the
evolutionary history of your groups of organisms being
Species
Fig. 19.6
common ancestor
enlarged brain
hair, mammary glands
Amniotic
egg
chimpanzee
long canine teeth
terrier
feathers
gizzard
four limbs
finch
crocodile
epidermal
scales
lizard
vertebrae
frog
common
ancestor
tuna
lancelet (outgroup)
1. A __________ is a
_______________
group. It consists of
an ancestral species
and ALL of its
descendants.
2. A
________________
group consists of an
ancestral species and
some, but not all of its
descendants
3. A
________________
__ group includes
taxa with different
ancestors.
CLADES
VS.
GROUPS
A
A
A
B
B
C
C
C
D
D
D
E
E
F
F
F
G
G
G
B
Group I
Group II
E
Group III
CLADE OR NOT?
D
D
B
B
B
E
E
C
A
E
C
F
G
common ancestor
D
H
I
A
C
F
G
H
I
A
F
G
H
I
In some trees, the length of a branch can
reflect the number of genetic changes
that have taken place in a particular DNA
sequence in that lineage
Drosophila
Lancelet
Zebrafish
542 mya
Frog
Which species
has gone
through the
most genetic
change?
Chicken
251 mya
Human
Mouse
Human
Mushroom
Tulip
0
30%
40%
0
40%
Human
Mushroom
0
Tulip
What is
maximum
parsimony?
What is
maximum
likelyhood?
Comparison of possible trees
15%
5%
5%
15%
15%
10%
25%
20%
Tree 1:
Percentage
differences
between
sequences
Tree 2:
Remember that phylogenetic tree are
. As new information is found,
these hypotheses can be
. The best hypotheses for
phylogenetic trees fit the most data: morphological,
molecular, and fossil. This has been applied to infer
features of dinosaurs from birds like me.
What kind of data allows
us to infer phylogenic
information?
_______________
_________________
•
_______________ structures:
Bones in the forelimbs of
mammals
•
Genes or other DNA sequences
are also homologous if they are
descended from a common
ancestor
Beware the
analogous
________________
__ evolution results
in this
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______________: Good, but incomplete. It is
often difficult to determine the phylogeny of a
fossil. Typically, hard parts are mineralized. Soft
tissued organisms tend to decay before they are
buried.
Watch TED-ed:
How to fossilize yourself
22
Analagous
scenarios can
also exist in
molecular data:
Coincidences:
Molecular
homoplasies
Molecular Data
• ___________________ Comparisons
– Systematics assumes:
• Two species with similar base-pair sequences are assumed to be
closely related
• Two species with differing base-pair sequences are assumed to be only
distantly related
• Mitochondrial DNA (mtDNA) often looked at as well because mutation
rate is 10x that of DNA
• ______________ Comparisons
– Immunological techniques
• Degree of cross reaction used to judge relationship
– Amino acid sequencing
• Similar sequence in same protein indicates close relationship
(cytochrome C)
• Molecular _____________
– We use non-adaptive nucleotide sequence
mutations (neutral)
– Assumed constant rate of mutation over time
– Fossil record + matching mutation rate = increased
strength in hypothesis
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Embryology and Development can reveals
homologies
Both organisms
end up
developing an
anus form from
the blastopore.
anus
Vertebrate
(modern bony fish)
blastopore
Anus develops from
blastopore in both
Echinoderm
(sea star)
Similar embryos
anus
Later the echinoderm becomes
radially symmetrical
Adult
sea star
A Three Domain System
Historically, scientists (after Aristotle’s time) grouped organisms into
two kingdoms, plants and animals
In the late 1800’s a third kingdom, the protists, was added.
In 1969, the five kingdom idea was brought forth.
Basis for placement into a
kingdom:
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Tree of Life
Showing The
Three Domains
In the 1970’s
the idea of
domains
based on
__________
became the
prominent
idea on how
to classify
organisms
fungi
animals
plants
protists
heterotrophic
cyanobacteria
bacteria
common ancestor
protists
Three-Domain System
 Sequencing of rRNA suggests all organisms
evolved along three distinct lineages:
Domain Bacteria Traits:
Domain Eukarya
Domain Archaea
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How these domains differ from one another
29