20 Phylogeny

Investigating the Evolutionary History of Life Legless lizards and snakes evolved from different lineages of lizards with legs Legless lizards have evolved independently in several different groups through adaptation to similar environments © 2016 Pearson Education, Inc.

Figure 20.1 What kind of organism is this? © 2016 Pearson Education, Inc.

No limbs Eastern glass lizard Monitor lizard Iguanas ANCESTRAL LIZARD Figure 20.2 No limbs Eastern glass lizard Monitor lizard Iguanas ANCESTRAL LIZARD (with limbs) Snakes Figure 20.2 Convergent evolution of limbless bodies No limbs Geckos © 2016 Pearson Education, Inc.

Phylogeny is the evolutionary history of a species or group of related species The discipline of systematics classifies organisms and determines their evolutionary relationships © 2016 Pearson Education, Inc. 5

Concept 20.1: Phylogenies show evolutionary relationships Organisms share many characteristics because of common ancestry Taxonomy is the ordered division and naming of organisms © 2016 Pearson Education, Inc. 6

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 © 2016 Pearson Education, Inc. 7

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) © 2016 Pearson Education, Inc. 8

Hierarchical Classification Linnaeus introduced a system for grouping species in increasingly broad categories The taxonomic groups from narrow to broad are species, genus, family, order, class, phylum, kingdom, and domain © 2016 Pearson Education, Inc. 9

Domain: Bacteria Kingdom: Animalia Domain: Archaea Domain: Eukarya Figure 20.3 Species: Panthera pardus Genus: Panthera Family: Felidae Order: Carnivora Class: Mammalia Figure 20.3 Linnaean classification Phylum: Chordata Domain: Bacteria Kingdom: Animalia Domain: Archaea Domain: Eukarya © 2016 Pearson Education, Inc.

A taxonomic unit at any level of hierarchy is called a taxon The broader taxa are not comparable between lineages For example, an order of snails has less genetic diversity than an order of mammals © 2016 Pearson Education, Inc. 11

Linking Classification and Phylogeny Systematists depict evolutionary relationships in branching phylogenetic trees © 2016 Pearson Education, Inc. 12

Order Family Genus Species Panthera Felidae Panthera pardus (leopard) Figure 20.4 Order Family Genus Species Panthera Felidae Panthera pardus (leopard) Taxidea Carnivora Taxidea taxus (American badger) Mustelidae Lutra Lutra lutra (European otter) Figure 20.4 The connection between classification and phylogeny Canis latrans (coyote) Canidae Canis Canis lupus (gray wolf) © 2016 Pearson Education, Inc.

Linnaean classification and phylogeny can differ from each other Systematists have proposed that classification be based entirely on evolutionary relationships © 2016 Pearson Education, Inc. 14

Sister taxa are groups that share an immediate common ancestor A phylogenetic tree represents a hypothesis about evolutionary relationships Each branch point represents the divergence of two taxa from a common ancestor Sister taxa are groups that share an immediate common ancestor © 2016 Pearson Education, Inc. 15

A polytomy is a branch from which more than two groups emerge A rooted tree includes a branch to represent the most recent common ancestor of all taxa in the tree A basal taxon diverges early in the history of a group and originates near the common ancestor of the group A polytomy is a branch from which more than two groups emerge © 2016 Pearson Education, Inc. 16

where lineages diverge Taxon A Figure 20.5 Branch point: where lineages diverge Taxon A Taxon B Sister taxa Taxon C Taxon D Taxon E ANCESTRAL LINEAGE Taxon F Figure 20.5 How to read a phylogenetic tree Basal taxon Taxon G This branch point represents the common ancestor of taxa A–G. This branch point forms a polytomy: an unresolved pattern of divergence. © 2016 Pearson Education, Inc.

What We Can and Cannot Learn from Phylogenetic Trees Phylogenetic trees show patterns of descent, not phenotypic similarity Phylogenetic trees do not generally indicate when a species evolved or how much change occurred in a lineage It should not be assumed that a taxon evolved from the taxon next to it © 2016 Pearson Education, Inc. 18

Applying Phylogenies Phylogeny provides important information about similar characteristics in closely related species Phylogenetic trees based on DNA sequences can be used to infer species identities For example: A phylogeny was used to identify the species of whale from which “whale meat” originated © 2016 Pearson Education, Inc. 19

Results Minke (Southern Hemisphere) mtDNA Unknown mtDNA #1a, Figure 20.6 Results Minke (Southern Hemisphere) mtDNA Unknown mtDNA #1a, 2, 3, 4, 5, 6, 7, 8 Minke (North Atlantic) mtDNA Unknown mtDNA #9 Humpback mtDNA Unknown mtDNA #1b Figure 20.6 Inquiry: What is the species identity of food being sold as whale meat? Blue mtDNA Unknown mtDNA #10, 11, 12, 13 Fin mtDNA © 2016 Pearson Education, Inc.

Concept 20.2: Phylogenies are inferred from morphological and molecular data To infer phylogeny, systematists gather information about morphologies, genes, and biochemistry of the relevant organisms The similarities used to infer phylogenies must result from shared ancestry © 2016 Pearson Education, Inc. 21

Morphological and Molecular Homologies Phenotypic and genetic similarities due to shared ancestry are called homologies Organisms with similar morphologies or DNA sequences are likely to be more closely related than organisms with different structures or sequences © 2016 Pearson Education, Inc. 22

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 © 2016 Pearson Education, Inc. 23

Convergent evolution occurs when similar environmental pressures and natural selection produce similar (analogous) adaptations in organisms from different evolutionary lineages © 2016 Pearson Education, Inc. 24

Australian marsupial mole Figure 20.7 Australian marsupial mole Figure 20.7 Convergent evolution in burrowers North American eutherian mole © 2016 Pearson Education, Inc.

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 © 2016 Pearson Education, Inc. 26

Evaluating Molecular Homologies Molecular homologies are determined based on the degree of similarity in nucleotide sequence between taxa Systematists use computer programs when analyzing comparable DNA segments from different organisms © 2016 Pearson Education, Inc. 27

Figure 20.8-s1 1 C A T G 2 C A T G Figure 20.8-s1 Aligning segments of DNA (step 1) © 2016 Pearson Education, Inc.

1 2 Deletion 1 2 Insertion C A T G C A T G C A T G C A T G G T A Figure 20.8-s2 1 C A T G 2 C A T G Deletion 1 C A T G 2 C A T G G T A Insertion Figure 20.8-s2 Aligning segments of DNA (step 2) © 2016 Pearson Education, Inc.

1 2 Deletion 1 2 Insertion 1 2 C A T G C A T G C A T G C A T G G T A C Figure 20.8-s3 1 C A T G 2 C A T G Deletion 1 C A T G 2 C A T G G T A Insertion 1 C A T G Figure 20.8-s3 Aligning segments of DNA (step 3) 2 C A T G © 2016 Pearson Education, Inc.

1 2 Deletion 1 2 Insertion 1 2 1 2 C A T G C A T G C A T G C A T G G T Figure 20.8-s4 1 C A T G 2 C A T G Deletion 1 C A T G 2 C A T G G T A Insertion 1 C A T G Figure 20.8-s4 Aligning segments of DNA (step 4) 2 C A T G 1 C A T G 2 C A T G © 2016 Pearson Education, Inc.

Shared bases in nucleotide sequences that are otherwise very dissimilar are called molecular homoplasies © 2016 Pearson Education, Inc. 32

A C G G A T A G T C C A C T A G G C A C T A Figure 20.9 A C G G A T A G T C C A C T A G G C A C T A T C A C C G A C A G G T C T T T G A C T A G Figure 20.9 A molecular homoplasy © 2016 Pearson Education, Inc.

Concept 20.3: Shared characters are used to construct phylogenetic trees Once homologous characters have been identified, they can be used to infer a phylogeny © 2016 Pearson Education, Inc. 34

Cladistics Cladistics classifies organisms by common descent A clade is a group of species that includes an ancestral species and all its descendants Clades can be nested within larger clades, but not all groupings of organisms qualify as clades © 2016 Pearson Education, Inc. 35

A valid clade is monophyletic, signifying that it consists of the ancestor species and all its descendants © 2016 Pearson Education, Inc. 36

(a) Monophyletic group (clade) Figure 20.10-1 (a) Monophyletic group (clade) A B Group I C D E Figure 20.10-1 Monophyletic, paraphyletic, and polyphyletic groups (part 1: monophyletic) F G © 2016 Pearson Education, Inc.

A paraphyletic grouping consists of an ancestral species and some, but not all, of the descendants © 2016 Pearson Education, Inc. 38

(b) Paraphyletic group Figure 20.10-2 (b) Paraphyletic group A B C D E Group II Figure 20.10-2 Monophyletic, paraphyletic, and polyphyletic groups (part 2: paraphyletic) F G © 2016 Pearson Education, Inc.

A polyphyletic grouping consists of various taxa with different ancestors © 2016 Pearson Education, Inc. 40

(c) Polyphyletic group Figure 20.10-3 (c) Polyphyletic group A B Group III C D E Figure 20.10-3 Monophyletic, paraphyletic, and polyphyletic groups (part 3: polyphyletic) F G © 2016 Pearson Education, Inc.

(a) Monophyletic group (clade) (b) Paraphyletic group Figure 20.10 (a) Monophyletic group (clade) (b) Paraphyletic group (c) Polyphyletic group A A A B Group I B B Group III C C C D D D E E Group II E Figure 20.10 Monophyletic, paraphyletic, and polyphyletic groups F F F G G G © 2016 Pearson Education, Inc.

In a paraphyletic group, the most recent common ancestor of all members of the group is part of the group In a polyphyletic group, the most recent common ancestor is not part of the group © 2016 Pearson Education, Inc. 43

Paraphyletic group Common ancestor of even-toed Other even-toed Figure 20.11 Paraphyletic group Common ancestor of even-toed ungulates Other even-toed ungulates Hippopotamuses Cetaceans Seals Figure 20.11 Paraphyletic vs. polyphyletic groups Bears Other carnivores Polyphyletic group © 2016 Pearson Education, Inc.

Shared Ancestral and Shared Derived Characters In comparison with its ancestor, an organism has both shared and different characteristics © 2016 Pearson Education, Inc. 45

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 © 2016 Pearson Education, Inc. 46

Inferring Phylogenies Using Derived Characters When inferring evolutionary relationships, it is useful to know in which clade a shared derived character first appeared © 2016 Pearson Education, Inc. 47

TAXA Lancelet (outgroup) (outgroup) Lancelet Lamprey Leopard Bass Figure 20.12 TAXA Lancelet (outgroup) (outgroup) Lancelet Lamprey Leopard Bass Turtle Frog Lamprey Vertebral column (backbone) 1 1 1 1 1 Bass Vertebral column CHARACTERS Hinged jaws 1 1 1 1 Frog Hinged jaws Four limbs 1 1 1 Turtle Amnion 1 1 Four limbs Figure 20.12 Using derived characters to infer phylogeny Hair 1 Amnion Leopard Hair (a) Character table (b) Phylogenetic tree © 2016 Pearson Education, Inc.

TAXA (outgroup) Lancelet Lamprey Leopard Turtle Bass Frog Figure 20.12-1 TAXA (outgroup) Lancelet Lamprey Leopard Turtle Bass Frog Vertebral column (backbone) 1 1 1 1 1 CHARACTERS Hinged jaws 1 1 1 1 Four limbs 1 1 1 Figure 20.12-1 Using derived characters to infer phylogeny (part 1: character table) Amnion 1 1 Hair 1 (a) Character table © 2016 Pearson Education, Inc.

Lancelet (outgroup) Lamprey Bass Vertebral column Frog Hinged jaws Figure 20.12-2 Lancelet (outgroup) Lamprey Bass Vertebral column Frog Hinged jaws Figure 20.12-2 Using derived characters to infer phylogeny (part 2: phylogenetic tree) Turtle Four limbs Amnion Leopard Hair (b) Phylogenetic tree © 2016 Pearson Education, Inc.

The outgroup is a group that has diverged before the ingroup An outgroup is a species or group of species that is closely related to the ingroup, the various species being studied The outgroup is a group that has diverged before the ingroup Systematists compare each ingroup species with the outgroup to differentiate between shared derived and shared ancestral characteristics © 2016 Pearson Education, Inc. 51

Characters shared by the outgroup and ingroup are ancestral characters that predate the divergence of both groups from a common ancestor © 2016 Pearson Education, Inc. 52

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 © 2016 Pearson Education, Inc. 53

Drosophila Lancelet Zebrafish Frog Chicken Human Mouse Figure 20.13 Figure 20.13 Branch lengths can represent genetic change. Human Mouse © 2016 Pearson Education, Inc.

In other trees, branch length can represent chronological time, and branching points can be determined from the fossil record © 2016 Pearson Education, Inc. 55

Drosophila Lancelet Zebrafish Frog Chicken Human Mouse 500 400 300 200 Figure 20.14 Drosophila Lancelet Zebrafish Frog Chicken Figure 20.14 Branch lengths can indicate time. Human Mouse 500 400 300 200 100 Present Millions of years ago © 2016 Pearson Education, Inc.

Maximum Parsimony Systematists can never be sure of finding the best tree in a large data set They narrow possibilities by applying the principle of maximum parsimony © 2016 Pearson Education, Inc. 57

Computer programs are used to search for trees that are parsimonious Maximum parsimony assumes that the tree that requires the fewest evolutionary events (appearances of shared derived characters) is the most likely Computer programs are used to search for trees that are parsimonious © 2016 Pearson Education, Inc. 58

Three phylogenetic hypotheses: Figure 20.15 Technique 1/C 1/C I I III II III II 1/C III II I Species I Species II Species III 1/C 1/C Three phylogenetic hypotheses: 3/A 2/T 3/A I I III I I III 2/T 3/A 4/C II III II II III II 4/C 4/C 2/T III II I III II I 3/A 4/C 2/T 4/C 2/T 3/A Site Figure 20.15 Research method: applying parsimony to a problem in molecular systematics 1 2 3 4 Results Species I C T A T I I III Species II C T T C II III II Species III A G A C III II I Ancestral sequence A G T T 6 events 7 events 7 events © 2016 Pearson Education, Inc.

Technique Species I Species II Species III Figure 20.15-1 Technique Species I Species II Species III Three phylogenetic hypotheses: Figure 20.15-1 Research method: applying parsimony to a problem in molecular systematics (part 1: hypotheses) I I III II III II III II I © 2016 Pearson Education, Inc.

Technique Site 1 2 3 4 Species I C T A T Species II C T T C Figure 20.15-2 Technique Site 1 2 3 4 Species I C T A T Species II C T T C Species III A G A C Figure 20.15-2 Research method: applying parsimony to a problem in molecular systematics (part 2: table) Ancestral sequence A G T T © 2016 Pearson Education, Inc.

Technique 1/C I I III 1/C II III II 1/C III II I 1/C 1/C 3/A 2/T 3/A I Figure 20.15-3 Technique 1/C I I III 1/C II III II 1/C III II I 1/C 1/C 3/A 2/T 3/A I I III Figure 20.15-3 Research method: applying parsimony to a problem in molecular systematics (part 3: comparison) 2/T 3/A 4/C II III II 4/C 4/C 2/T III II I 3/A 4/C 2/T 4/C 2/T 3/A © 2016 Pearson Education, Inc.

Results I I III II III II III II I 6 events 7 events 7 events Figure 20.15-4 Results I I III II III II III II I Figure 20.15-4 Research method: applying parsimony to a problem in molecular systematics (part 4: results) 6 events 7 events 7 events © 2016 Pearson Education, Inc.

Phylogenetic Trees as Hypotheses The best hypothesized phylogenetic tree fits the most data: morphological, molecular, and fossil Phylogenetic hypotheses are modified when new evidence arises © 2016 Pearson Education, Inc. 64

Phylogenetic bracketing allows us to predict features of ancestors and their extinct descendants based on the features of closely related living descendants For example, phylogenetic bracketing allows us to infer characteristics of dinosaurs based on shared characters in modern birds and crocodiles © 2016 Pearson Education, Inc. 65

†Saurischian dinosaurs other than birds Figure 20.16 Lizards and snakes Crocodilians †Ornithischian dinosaurs Common ancestor of crocodilians, dinosaurs, and birds †Saurischian dinosaurs other than birds Figure 20.16 A phylogenetic tree of birds and their close relatives Birds © 2016 Pearson Education, Inc.

Birds and crocodiles share several features: four-chambered hearts, song, nest building, and egg brooding These characteristics likely evolved in a common ancestor and were shared by all of its descendants, including dinosaurs © 2016 Pearson Education, Inc. 67

Figure 20.17 A crocodile guards its nest. © 2016 Pearson Education, Inc.

The fossil record supports nest building and brooding in dinosaurs © 2016 Pearson Education, Inc. 69

(a) Fossil remains of Oviraptor and eggs Figure 20.18 Front limb Hind limb Eggs Figure 20.18 Fossil support for a phylogenetic prediction: Dinosaurs built nests and brooded their eggs. (a) Fossil remains of Oviraptor and eggs (b) Artist’s reconstruction of the dinosaur’s posture based on the fossil findings © 2016 Pearson Education, Inc.

(a) Fossil remains of Oviraptor and eggs Figure 20.18-1 Front limb Hind limb Figure 20.18-1 Fossil support for a phylogenetic prediction: Dinosaurs built nests and brooded their eggs. (part 1: fossil) Eggs (a) Fossil remains of Oviraptor and eggs © 2016 Pearson Education, Inc.

Concept 20.4: Molecular clocks help track evolutionary time To extend molecular phylogenies beyond the fossil record, we must make an assumption about how molecular change occurs over time © 2016 Pearson Education, Inc. 72

Molecular Clocks A molecular clock uses constant rates of evolution in some genes to estimate the absolute time of evolutionary change The number of nucleotide substitutions in related genes is assumed to be proportional to the time since they last shared a common ancestor © 2016 Pearson Education, Inc. 73

Individual genes vary in how clocklike they are Molecular clocks are calibrated by plotting the number of genetic changes against the dates of branch points known from the fossil record Individual genes vary in how clocklike they are © 2016 Pearson Education, Inc. 74

Divergence time (millions of years) Figure 20.19 90 Number of mutations 60 30 Figure 20.19 A molecular clock for mammals 30 60 90 120 Divergence time (millions of years) © 2016 Pearson Education, Inc.

Differences in Clock Speed Some mutations are selectively neutral and have little or no effect on fitness Neutral mutations should be regular like a clock The mutation rate is dependent on how critical a gene’s amino acid sequence is to survival © 2016 Pearson Education, Inc. 76

Potential Problems with Molecular Clocks Molecular clocks do not run as smoothly as expected if mutations were selectively neutral Irregularities result from natural selection in which some DNA changes are favored over others Estimates of evolutionary divergences older than the fossil record have a high degree of uncertainty The use of multiple genes may improve estimates © 2016 Pearson Education, Inc. 77

Applying a Molecular Clock: Dating the Origin of HIV Phylogenetic analysis shows that HIV is descended from viruses that infect chimpanzees and other primates HIV spread to humans more than once Comparison of HIV samples shows that the virus evolved in a very clocklike way © 2016 Pearson Education, Inc. 78

Animation: Class Schemes © 2016 Pearson Education, Inc.

Index of base changes between HIV Figure 20.20 Index of base changes between HIV gene sequences 0.15 HIV 0.10 Range Adjusted best-fit line (accounts for uncertain dates of HIV sequences) 0.05 Figure 20.20 Dating the origin of HIV-1 M 1900 1920 1940 1960 1980 2000 Year © 2000 AAAS © 2016 Pearson Education, Inc.

Application of a molecular clock to one strain of HIV suggests that that strain spread to humans during the 1930s A more advanced molecular clock approach has dated the origin of that strain to about 1910 © 2016 Pearson Education, Inc. 81

Concept 20.5: New information continues to revise our understanding of evolutionary history Recently, systematists have gained insight into the very deepest branches of the tree of life through analysis of DNA sequence data © 2016 Pearson Education, Inc. 82

From Two Kingdoms to Three Domains Early taxonomists classified all species as either plants or animals Later, five kingdoms were recognized: Monera (prokaryotes), Protista, Plantae, Fungi, and Animalia More recently, the three-domain system has been adopted: Bacteria, Archaea, and Eukarya The three-domain system is supported by data from many sequenced genomes © 2016 Pearson Education, Inc. 83

Euglenozoans Forams Diatoms Domain Eukarya Ciliates Red algae Figure 20.21 Euglenozoans Forams Diatoms Domain Eukarya Ciliates Red algae Green algae Plants Amoebas Fungi Animals Nanoarchaeotes Archaea Domain Euryarcheotes Crenarcheotes COMMON ANCESTOR OF ALL LIFE Figure 20.21 The three domains of life Proteobacteria (Mitochondria)* Domain Bacteria Chlamydias Spirochetes Gram-positive bacteria Cyanobacteria (Chloroplasts)* © 2016 Pearson Education, Inc.

Euglenozoans Forams Diatoms Domain Eukarya Ciliates Red algae Figure 20.21-1 Euglenozoans Forams Diatoms Domain Eukarya Ciliates Red algae Green algae Plants Figure 20.21-1 The three domains of life (part 1: eukarya) Amoebas Fungi Animals © 2016 Pearson Education, Inc.

Nanoarchaeotes Archaea Domain Euryarcheotes Crenarcheotes Figure 20.21-2 Nanoarchaeotes Archaea Domain Euryarcheotes Crenarcheotes Figure 20.21-2 The three domains of life (part 2: archaea) © 2016 Pearson Education, Inc.

Proteobacteria (Mitochondria)* Domain Bacteria Chlamydias Spirochetes Figure 20.21-3 Proteobacteria (Mitochondria)* Domain Bacteria Chlamydias Spirochetes Gram-positive bacteria Figure 20.21-3 The three domains of life (part 3: bacteria) Cyanobacteria (Chloroplasts)* © 2016 Pearson Education, Inc.

Domains Bacteria and Archaea are single-celled prokaryotes The three-domain system highlights the importance of single-celled organisms in the history of life Domains Bacteria and Archaea are single-celled prokaryotes Only three lineages in the domain Eukarya are dominated by multicellular organisms, kingdoms Plantae, Fungi, and Animalia © 2016 Pearson Education, Inc. 88

The Important Role of Horizontal Gene Transfer The tree of life suggests that eukaryotes and archaea are more closely related to each other than to bacteria The tree of life is based largely on rRNA genes, which have evolved slowly, allowing detection of homologies between distantly related organisms Other genes indicate different evolutionary relationships © 2016 Pearson Education, Inc. 89

Horizontal gene transfer complicates efforts to build a tree of life There have been substantial interchanges of genes between organisms in different domains Horizontal gene transfer is the movement of genes from one genome to another Horizontal gene transfer occurs by exchange of transposable elements and plasmids, viral infection, and fusion of organisms Horizontal gene transfer complicates efforts to build a tree of life © 2016 Pearson Education, Inc. 90

Horizontal gene transfer may have been common enough that the early history of life is better depicted by a tangled web than a branching tree © 2016 Pearson Education, Inc. 91

Domain Eukarya Archaea Domain Ancestral cell populations Figure 20.22 Domain Eukarya Ani malia Fungi Plantae Chloropl asts Archaea Domain Mitochondria Methanogens Ancestral cell populations Thermophiles Figure 20.22 A tangled web of life Cyanobacteria Domain Bacteria Proteobacteria © 2016 Pearson Education, Inc.

alia Anim Domain Eukarya Fungi Plantae Mito Chlo ch Ancestral cell Figure 20.22-1 Anim alia Domain Eukarya Fungi Plantae Mito ondria ch Chlo asts ropl Ancestral cell populations Figure 20.22-1 A tangled web of life (part 1: eukarya) © 2016 Pearson Education, Inc.

Methanogens Archaea Domain M it o c h ndri a Chlo asts ropl Figure 20.22-2 Methanogens Archaea Domain M it o c h ndri a Chlo asts ropl Thermophiles Ancestral cell populations Cyanobacteria Domain Bacteria Proteobacteria Figure 20.22-2 A tangled web of life (part 2: archaea and bacteria) © 2016 Pearson Education, Inc.

A B D B D C C C B D A A (a) (b) (c) Figure 20.UN01 Figure 20.UN01 Concept check 20.1, p. 399 (a) (b) (c) © 2016 Pearson Education, Inc.

Reptiles (including birds) OTHER TETRAPODS †Dimetrodon †Cynodonts Figure 20.UN02 Reptiles (including birds) OTHER TETRAPODS †Dimetrodon †Cynodonts Figure 20.UN02 Concept check 20.3, p. 406 Mammals © 2016 Pearson Education, Inc.

Figure 20.UN03-1 Figure 20.UN03-1 Skills exercise: using protein sequence data to test an evolutionary hypothesis (part 1) © 2016 Pearson Education, Inc.

Figure 20.UN03-2 Figure 20.UN03-2 Skills exercise: using protein sequence data to test an evolutionary hypothesis (part 2) © 2016 Pearson Education, Inc.

Branch point Taxon A Most recent common ancestor Taxon B Sister taxa Figure 20.UN04 Branch point Taxon A Most recent common ancestor Taxon B Sister taxa Taxon C Taxon D Taxon E Figure 20.UN04 Summary of key concepts: evolutionary relationships Polytomy Taxon F Taxon G Basal taxon © 2016 Pearson Education, Inc.

Monophyletic group Polyphyletic group A A A B B B C C C D D D E E E F Figure 20.UN05 Monophyletic group Polyphyletic group A A A B B B C C C D D D E E E Figure 20.UN05 Summary of key concepts: shared characters F F F G G G Paraphyletic group © 2016 Pearson Education, Inc.

Salamander Lizard Goat Human Figure 20.UN06 Figure 20.UN06 Test your understanding, question 5 (interpreting a tree) Human © 2016 Pearson Education, Inc.

Figure 20.UN07 Test your understanding, question 8 (drawing a tree) © 2016 Pearson Education, Inc.

Figure 20.UN08 Figure 20.UN08 Test your understanding, question 11 (West Indian manatee) © 2016 Pearson Education, Inc.