big idea #1 – part b descent from common ancestry section 2:
DESCRIPTION
Big Idea #1 – part B Descent from Common Ancestry section 2:. Phylogenetic Trees and Cladograms (26.1-26.3). Overview: Investigating the Tree of Life. Phylogeny is the evolutionary history of a species or group of related species - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/1.jpg)
Big Idea #1 – part B Descent from Common
Ancestry section 2:
Phylogenetic Trees and Cladograms (26.1-26.3)
![Page 2: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/2.jpg)
Overview: Investigating the Tree of LifePhylogeny is the evolutionary history of
a species or group of related speciesThe discipline of systematics classifies
organisms and determines their evolutionary relationships
Systematists use fossil, molecular, and genetic data to infer evolutionary relationships
![Page 3: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/3.jpg)
Fig. 26-2
![Page 4: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/4.jpg)
Concept 26.1: Phylogenies show evolutionary relationships
Taxonomy is the ordered division and naming of organisms
![Page 5: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/5.jpg)
Binomial Nomenclature
In the 18th century, Carolus Linnaeus published a system of taxonomy based on resemblances
Two key features of his system remain useful today: two-part names for species and hierarchical classification
![Page 6: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/6.jpg)
The two-part scientific name of a species is called a binomial
The first part of the name is the genus The second part, called the specific
epithet, is unique for each species within the genus
The first letter of the genus is capitalized, and the entire species name is italicized
Both parts together name the species (not the specific epithet alone)
![Page 7: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/7.jpg)
Hierarchical Classification
Linnaeus introduced a system for grouping species in increasingly broad categories
The taxonomic groups from broad to narrow are domain, kingdom, phylum, class, order, family, genus, and species
A taxonomic unit at any level of hierarchy is called a taxon
![Page 8: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/8.jpg)
Fig. 26-3Species:Pantherapardus
Genus: Panthera
Family: Felidae
Order: Carnivora
Class: Mammalia
Phylum: Chordata
Kingdom: Animalia
Archaea
Domain: Eukarya
Bacteria
![Page 9: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/9.jpg)
Fig. 26-3a
Class: Mammalia
Phylum: Chordata
Kingdom: Animalia
ArchaeaDomain: Eukarya
Bacteria
![Page 10: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/10.jpg)
Fig. 26-3b
Species:Pantherapardus
Genus: Panthera
Family: Felidae
Order: Carnivora
![Page 11: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/11.jpg)
Linking Classification and Phylogeny
Systematists depict evolutionary relationships in branching phylogenetic trees
![Page 12: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/12.jpg)
Fig. 26-4 Species
Canislupus
Pantherapardus
Taxideataxus
Lutra lutra
Canislatrans
Order
Family
Genus
Carnivora
Felidae
Mustelida
eCanidae Canis
Lutra
Taxidea
Panthera
![Page 13: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/13.jpg)
Linnaean classification and phylogeny can differ from each other
Systematists have proposed the PhyloCode, which recognizes only groups that include a common ancestor and all its descendents
![Page 14: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/14.jpg)
A phylogenetic tree represents a hypothesis about evolutionary relationships
Each branch point represents the divergence of two species
Sister taxa are groups that share an immediate common ancestor
![Page 15: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/15.jpg)
A rooted tree includes a branch to represent the last common ancestor of all taxa in the tree
A polytomy is a branch from which more than two groups emerge
![Page 16: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/16.jpg)
Fig. 26-5
Sistertaxa
ANCESTRALLINEAGE
Taxon A
Polytomy
Common ancestor oftaxa A–F
Branch point(node)
Taxon BTaxon CTaxon DTaxon E
Taxon F
![Page 17: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/17.jpg)
What We Can and Cannot Learn from Phylogenetic
TreesPhylogenetic trees do show patterns of
descentPhylogenetic trees do not indicate when
species evolved or how much genetic change occurred in a lineage
It shouldn’t be assumed that a taxon evolved from the taxon next to it
![Page 18: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/18.jpg)
Applying PhylogeniesPhylogeny provides important
information about similar characteristics in closely related species
A phylogeny was used to identify the species of whale from which “whale meat” originated
![Page 19: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/19.jpg)
Fig. 26-6
Fin(Mediterranean)Fin (Iceland)
RESULTS
Unknown #10,11, 12Unknown #13
Blue(North Pacific)
Blue(North Atlantic)
Gray
Unknown #1b
Humpback(North Atlantic)Humpback(North Pacific)
Unknown #9
Minke(North Atlantic)
Minke(Antarctica)Minke(Australia)Unknown #1a,2, 3, 4, 5, 6, 7, 8
![Page 20: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/20.jpg)
Fig. 26-6a
Unknown #9
Minke(North Atlantic)
Minke(Antarctica)Minke(Australia)Unknown #1a,2, 3, 4, 5, 6, 7, 8
RESULTS
![Page 21: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/21.jpg)
Fig. 26-6b
Blue(North Pacific)
Blue(North Atlantic)
Gray
Unknown #1b
Humpback(North Atlantic)Humpback(North Pacific)
![Page 22: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/22.jpg)
Fig. 26-6c
Fin(Mediterranean)Fin (Iceland)
Unknown #13
Unknown #10,11, 12
![Page 23: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/23.jpg)
Phylogenies of anthrax bacteria helped researchers identify the source of a particular strain of anthrax
![Page 24: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/24.jpg)
Fig. 26-UN1
A
B
A A
B
B
C
CC
D
D
D
(a) (b) (c)
![Page 25: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/25.jpg)
Concept 26.2: Phylogenies are inferred from morphological and
molecular dataTo infer phylogenies, systematists
gather information about morphologies, genes, and biochemistry of living organisms
![Page 26: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/26.jpg)
Morphological and Molecular Homologies
Organisms with similar morphologies or DNA sequences are likely to be more closely related than organisms with different structures or sequences
![Page 27: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/27.jpg)
Sorting Homology from Analogy
When constructing a phylogeny, systematists need to distinguish whether a similarity is the result of homology or analogy
Homology is similarity due to shared ancestry
Analogy is similarity due to convergent evolution
![Page 28: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/28.jpg)
Fig. 26-7
![Page 29: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/29.jpg)
Convergent evolution occurs when similar environmental pressures and natural selection produce similar (analogous) adaptations in organisms from different evolutionary lineages
![Page 30: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/30.jpg)
Bat and bird wings are homologous as forelimbs, but analogous as functional wings
Analogous structures or molecular sequences that evolved independently are also called homoplasies
Homology can be distinguished from analogy by comparing fossil evidence and the degree of complexity
The more complex two similar structures are, the more likely it is that they are homologous
![Page 31: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/31.jpg)
Evaluating Molecular Homologies
Systematists use computer programs and mathematical tools when analyzing comparable DNA segments from different organisms
![Page 32: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/32.jpg)
Fig. 26-8
Deletion
Insertion
1
2
3
4
![Page 33: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/33.jpg)
Fig. 26-8a
Deletion
Insertion
1
2
![Page 34: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/34.jpg)
Fig. 26-8b
3
4
![Page 35: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/35.jpg)
It is also important to distinguish homology from analogy in molecular similarities
Mathematical tools help to identify molecular homoplasies, or coincidences
Molecular systematics uses DNA and other molecular data to determine evolutionary relationships
![Page 36: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/36.jpg)
Fig. 26-9
![Page 37: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/37.jpg)
Concept 26.3: Shared characters are used to construct phylogenetic
trees
Once homologous characters have been identified, they can be used to infer a phylogeny
![Page 38: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/38.jpg)
CladisticsCladistics groups organisms by
common descentA clade is a group of species that
includes an ancestral species and all its descendants
Clades can be nested in larger clades, but not all groupings of organisms qualify as cladesA valid clade is monophyletic, signifying
that it consists of the ancestor species and all its descendants
![Page 39: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/39.jpg)
A valid clade is monophyletic, signifying that it consists of the ancestor species and all its descendants
![Page 40: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/40.jpg)
Fig. 26-10
A A ABBB
C C CDDD
E E EFFF
G G G
Group III
Group II
Group I
(a) Monophyletic group (clade)
(b) Paraphyletic group
(c) Polyphyletic group
![Page 41: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/41.jpg)
Fig. 26-10a
AB
CD
EF
G
Group I
(a) Monophyletic group (clade)
![Page 42: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/42.jpg)
A paraphyletic grouping consists of an ancestral species and some, but not all, of the descendants
![Page 43: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/43.jpg)
Fig. 26-10b
AB
CD
EF
G
Group II
(b) Paraphyletic group
![Page 44: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/44.jpg)
A polyphyletic grouping consists of various species that lack a common ancestor
![Page 45: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/45.jpg)
Fig. 26-10c
AB
CD
EF
G
Group III
(c) Polyphyletic group
![Page 46: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/46.jpg)
Shared Ancestral and Shared Derived Characters
In comparison with its ancestor, an organism has both shared and different characteristics
![Page 47: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/47.jpg)
A shared ancestral character is a character that originated in an ancestor of the taxon
A shared derived character is an evolutionary novelty unique to a particular clade
A character can be both ancestral and derived, depending on the context
![Page 48: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/48.jpg)
Inferring Phylogenies Using Derived Characters
When inferring evolutionary relationships, it is useful to know in which clade a shared derived character first appeared
![Page 49: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/49.jpg)
Fig. 26-11
TAXA
Lanc
elet
(out
grou
p) Lam
prey
Sal a
ma n
d er Le
opar
dTurt
leTu
naVertebral column
(backbone)
Hinged jaws
Four walking legs
Amniotic (shelled) egg
CHAR
ACT E
RS
Hair
(a) Character table
Hair
Hinged jaws
Vertebral
column
Four walking legs
Amniotic egg
(b) Phylogenetic tree
Salamander
Leopard
Turtle
Lamprey
Tuna
Lancelet(outgroup)
0
0 0
0
0
0
0 0
0
0
0 0
0 0 0 1
11
111
1
11
1
1
11
11
![Page 50: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/50.jpg)
Fig. 26-11aTAXA
Lanc
elet
(out
grou
p) Lam
prey
Sala
ma n
der Le
opar
d
Turt
leTu
na
Vertebral column
(backbone)Hinged
jawsFour walking legs
Amniotic (shelled) egg
CHAR
ACTE
RS
Hair
(a) Character table
0
0 0
0
0
0
0 0
0
0
0 0
0 0 0 1
11
111
1
11
1
1
11
11
![Page 51: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/51.jpg)
Fig. 26-11b
Hair
Hinged jaws
Vertebral
column
Four walking legs
Amniotic egg
(b) Phylogenetic tree
Salamander
Leopard
Turtle
Lamprey
Tuna
Lancelet(outgroup)
![Page 52: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/52.jpg)
An outgroup is a species or group of species that is closely related to the ingroup, the various species being studied
Systematists compare each ingroup species with the outgroup to differentiate between shared derived and shared ancestral characteristics
![Page 53: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/53.jpg)
Homologies shared by the outgroup and ingroup are ancestral characters that predate the divergence of both groups from a common ancestor
![Page 54: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/54.jpg)
Phylogenetic Trees with Proportional Branch Lengths
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
![Page 55: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/55.jpg)
Fig. 26-12
Drosophila
Lancelet
Zebrafish
Frog
Human
Chicken
Mouse
![Page 56: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/56.jpg)
In other trees, branch length can represent chronological time, and branching points can be determined from the fossil record
![Page 57: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/57.jpg)
Fig. 26-13
Drosophila
Lancelet
Zebrafish
Frog
Human
Chicken
Mouse
CENOZOICPresent
65.5
MESOZOIC25
1Millions of years ago
PALEOZOIC54
2
![Page 58: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/58.jpg)
Maximum Parsimony and Maximum Likelihood
Systematists can never be sure of finding the best tree in a large data set
They narrow possibilities by applying the principles of maximum parsimony and maximum likelihood
![Page 59: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/59.jpg)
Maximum parsimony assumes that the tree that requires the fewest evolutionary events (appearances of shared derived characters) is the most likely
The principle of maximum likelihood states that, given certain rules about how DNA changes over time, a tree can be found that reflects the most likely sequence of evolutionary events
![Page 60: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/60.jpg)
Fig. 26-14
Human
15%
Tree 1: More likely
Tree 2: Less likely(b) Comparison of possible
trees
15% 15%5%
5%
10%25%20%
40%
40%
30%0
0
0
(a) Percentage differences between sequences
Human Mushroom
MushroomTulip
Tulip
![Page 61: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/61.jpg)
Fig. 26-14a
Human
40%
40%
30%0
0
0
(a) Percentage differences between sequences
Human Mushroom
MushroomTulip
Tulip
![Page 62: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/62.jpg)
Fig. 26-14b
15%
Tree 1: More likely
Tree 2: Less likely(b) Comparison of possible
trees
15%
15%
5%
5%
10%
25%
20%
![Page 63: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/63.jpg)
Computer programs are used to search for trees that are parsimonious and likely
![Page 64: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/64.jpg)
Fig. 26-15-1
Species I
Three phylogenetic hypotheses:
Species II Species III
I
II
III
I
III
IIIII
III
![Page 65: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/65.jpg)
Fig. 26-15-2
Species I
Site
Species II
Species III
I
II
III
I
III
IIIII
III
Ancestral
sequence
1/C1/C
1/C
1/C
1/C
4321
C
C C
C
T
T
T
T
T
T A
AA
A G
G
![Page 66: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/66.jpg)
Fig. 26-15-3
Species I
Site
Species II
Species III
I
II
III
I
III
IIIII
III
Ancestral
sequence
1/C1/C
1/C
1/C
1/C
4321
C
C C
C
T
T
T
T
T
T A
AA
A G
G
I I
I
II
II
II
III
III
III3/A
3/A
3/A3/A
3/A
2/T2/T
2/T 2/T
2/T4/C
4/C
4/C
4/C
4/C
![Page 67: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/67.jpg)
Fig. 26-15-4
Species I
Site
Species II
Species III
I
II
III
I
III
IIIII
III
Ancestral
sequence
1/C1/C
1/C
1/C
1/C
4321
C
C C
C
T
T
T
T
T
T A
AA
A G
G
I I
I
II
II
II
III
III
III3/A
3/A
3/A3/A
3/A
2/T2/T
2/T 2/T
2/T4/C
4/C
4/C
4/C
4/C
I I
I
II
II
II
III
III
III
7 events
7 events
6 events
![Page 68: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/68.jpg)
Phylogenetic Trees as Hypotheses
The best hypotheses for phylogenetic trees fit the most data: morphological, molecular, and fossil
Phylogenetic bracketing allows us to predict features of an ancestor from features of its descendents
![Page 69: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/69.jpg)
Fig. 26-16
Commonancestor ofcrocodilians,dinosaurs,and birds
Birds
Lizardsand snakesCrocodilians
OrnithischiandinosaursSaurischiandinosaurs
![Page 70: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/70.jpg)
This has been applied to infer features of dinosaurs from their descendents: birds and crocodiles
Animation: The Geologic Record
![Page 71: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/71.jpg)
Fig. 26-17
Eggs
Front limb
Hind limb
(a) Fossil remains of Oviraptor and eggs
(b) Artist’s reconstruction of the dinosaur’s posture
![Page 72: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/72.jpg)
Fig. 26-17a
Eggs
Front limb
Hind limb
(a) Fossil remains of Oviraptor
and eggs
![Page 73: Big Idea #1 – part B Descent from Common Ancestry section 2:](https://reader035.vdocuments.site/reader035/viewer/2022062410/56816585550346895dd833c0/html5/thumbnails/73.jpg)
Fig. 26-17b
(b) Artist’s reconstruction of the dinosaur’s posture