organization of all that speciation!...• a cladogram is an evolutionary tree made using...

17.2 Classification Based on Evolutionary Relationships

Organization of all that speciation!

• Patterns of evolution…..

17.2 Classification Based on Evolutionary Relationships

17.2 Classification Based on Evolutionary Relationships

Taxonomy gets an over haul! Using more than

morphology!

3 domains, 6 kingdoms

17.2 Classification Based on Evolutionary Relationships

17.2 Classification Based on Evolutionary Relationships

KEY CONCEPT

Modern classification is based on evolutionary

relationships. Called Systematics/Cladistics

17.2 Classification Based on Evolutionary Relationships

Cladistics is classification based on common ancestry.

• Phylogeny is the evolutionary history for a group of species.

– evidence from living species, fossil record, and

molecular data

– shown with branching tree diagrams

17.2 Classification Based on Evolutionary Relationships

• A cladogram is an evolutionary tree made using cladistics.

– A clade is a group of species that shares a common

ancestor.

– Each species

in a clade

shares some

traits with the

ancestor.

– Each species

in a clade has

traits that have

changed.

17.2 Classification Based on Evolutionary Relationships

Plants?

• Bryophyte

• Tracheophyte

• Gymnosperm

• Angiosperm

17.2 Classification Based on Evolutionary Relationships

• Derived characters are traits shared in different degrees by

clade members (synapomorphies).

– basis of arranging

species in

cladogram

– more closely

related species

share more

derived characters

– represented on

cladogram as hash

marks on the “x”

axisFOUR LIMBS WITH DIGITS

Tetrapoda clade1

Amniota clade2

Reptilia clade3Diapsida clade4

Archosauria clade5

EMBRYO PROTECTED BY AMNIOTIC FLUID

OPENING IN THE SIDE OF

THE SKULL

SKULL OPENINGS IN

FRONT OF THE EYE &

IN THE JAW

FEATHERS &

TOOTHLESS

BEAKS.

SKULL OPENINGS BEHIND THE EYE

DERIVED CHARACTER

17.2 Classification Based on Evolutionary Relationships

FOUR LIMBS WITH DIGITS

• Nodes represent

the most recent

common ancestor

of a clade.

• Clades can be

identified by

snipping a branch

under a node.

Tetrapoda clade1

Amniota clade2

Reptilia clade3Diapsida clade4

Archosauria clade5

EMBRYO PROTECTED BY AMNIOTIC FLUID

OPENING IN THE SIDE OF

THE SKULL

SKULL OPENINGS IN

FRONT OF THE EYE AND

IN THE JAW

FEATHERS AND

TOOTHLESS

BEAKS.

SKULL OPENINGS BEHIND THE EYE

NODE

DERIVED CHARACTER

CLADE

17.2 Classification Based on Evolutionary Relationships

CLADE/MONOPHYLETIC TAXON: A group of organisms, that are derived

from a common ancestor.

EX: Birds and reptiles and the reptilian ancestor

TAXON (TAXA): Group of organisms

PARAPHYLETIC TAXON: A group of organisms that does not include all

possibly related organisms. EX: Looking at just birds and then reptiles separately

Out-group is the least related group on the far left!

17.2 Classification Based on Evolutionary Relationships

Outcomes?

17.2 Classification Based on Evolutionary Relationships

Steps to making a cladogram:

1. Determine the traits to assess in order of evolutionary complexity.

2. Create a table of who has the traits and who does not

3. Arrange the traits along the bottom of the diagram and the

organisms coming off that line .(Most advanced organism will be

on the top right when done)

4. Determine common ancestry along the way to determine if new

branch is needed or if one organism derives but does not have new

ancestry.

17.2 Classification Based on Evolutionary Relationships

17.2 Classification Based on Evolutionary Relationships

17.2 Classification Based on Evolutionary Relationships

17.2 Classification Based on Evolutionary Relationships

17.2 Classification Based on Evolutionary Relationships

Anatomical tools

• Homologous structures (shared homology)-structure has

same ancestry and anatomy, even though immediate

function differs:

17.2 Classification Based on Evolutionary Relationships

• Vestigial- structure has huge function in one group, little

or no function in another

17.2 Classification Based on Evolutionary Relationships

• Analogous structure (analogy)-structure has same

immediate function but not ancestry or anatomy. Ex: bee

wings and bird wings

17.2 Classification Based on Evolutionary Relationships

• Molecular clock- once divergence from a common

ancestor occurs and each species lineage continues to

evolve separately, DNA mutations can be compared to

measure genetic differences between the group.

• Tend to use proteins that have plasticity without losing

function. (Ex: not hemoglobin)

• Cytochrome C is better choice. EX: Species A has a 6%

base pair difference in molecule from B, A and C have a

32% difference, who is more closely related? Why?