TAXONOMY 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 1

Euglenozoans Forams Diatoms Ciliates Domain Eukarya Red algae Green algae Land plants Amoebas Fungi Animals Nanoarchaeotes Archaea Domain Methanogens COMMON ANCESTOR OF ALL LIFE Thermophiles Figure 20.20 The three domains of life Proteobacteria (Mitochondria)* Chlamydias Spirochetes Domain Bacteria Gram-positive bacteria Cyanobacteria (Chloroplasts)* 2

Classification systems Six-Kingdom Scheme Classification systems 3

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 4

Comparative Morphology Study of similarities and differences in body plans of major groups Puzzling patterns: Animals as different as whales and bats have similar bones in forelimbs Some parts seem to have no function Guiding principle: When it comes to introducing change in morphology, evolution tends to follow the path of least resistance

Morphological Divergence Change from body form of a common ancestor Produces homologous structures

Comparative pelvic anatomy Comparative Morphology Comparative pelvic anatomy

Morphological Convergence Individuals of different lineages evolve in similar ways under similar environmental pressures Produces analogous structures that serve similar functions

Morphological Convergence

Comparative Development Each animal or plant proceeds through a series of changes in form Similarities in these stages may be clues to evolutionary relationships Mutations that disrupt a key stage of development are selected against

Similar Vertebrate Embryos Alterations that disrupted early development have been selected against FISH REPTILE BIRD MAMMAL

Comparative Biochemistry Kinds and numbers of biochemical traits that species share is a clue to how closely they are related Can compare DNA, RNA, or proteins More similarity means species are more closely related

Comparing Proteins Compare amino acid sequence of proteins produced by the same gene Human cytochrome c (a protein) Identical amino acids in chimpanzee protein Chicken protein differs by 18 amino acids Yeast protein differs by 56

Taxonomy Field of biology concerned with identifying, naming, and classifying species Somewhat subjective Information about species can be interpreted differently 14

Binomial System Devised by Carl von Linneas Each species has a two-part Latin name First part is generic Second part is specific name 15

Higher Taxa Kingdom Phylum Class Order Family Genus Species 16

Kingdom: Animalia Domain: Bacteria Domain: Archaea Domain: Eukarya Species: Panthera pardus Genus: Panthera Family: Felidae Order: Carnivora Class: Mammalia Figure 20.3 Linnaean classification Phylum: Chordata Kingdom: Animalia Domain: Bacteria Domain: Archaea Domain: Eukarya 17

Examples of Classification 18

Cladistics Cladistics classifies organisms by common descent A clade is a group of species that includes an ancestral species and all its descendants 19

A valid clade is monophyletic, signifying that it consists of the ancestor species and all its descendants A 1 B Group I C D Figure 20.10a Monophyletic, paraphyletic, and polyphyletic groups (part 1: monophyletic) E F G 20

A paraphyletic grouping consists of an ancestral species and some, but not all, of the descendants A B C D Figure 20.10b Monophyletic, paraphyletic, and polyphyletic groups (part 2: paraphyletic) E Group II 2 F G 21

A polyphyletic grouping consists of various taxa with different ancestors A 1 B Group III C D Figure 20.10c Monophyletic, paraphyletic, and polyphyletic groups (part 3: polyphyletic) E 2 F G 22

(a) Monophyletic group (clade) (b) Paraphyletic group (c) Polyphyletic group A A A 1 1 B Group I B B Group III C C C D D D E E Group II E 2 2 F F F G G G 23

Shared Ancestral and Shared Derived Characters In comparison with its ancestor, an organism has both shared and different characteristics 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 24

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 Drosophila Lancelet Zebrafish Frog Chicken Human Mouse 25

In other trees, branch length can represent chronological time, and branching points can be determined from the fossil record Drosophila Lancelet Zebrafish Frog Figure 20.13 Branch lengths can indicate time Chicken Human Mouse PALEOZOIC MESOZOIC CENOZOIC 251 65.5 Present 542 Millions of years ago 26

Evolutionary tree diagram Evolutionary Trees Evolutionary tree diagram

Evolutionary Trees extinction (branch ended before present) new species branch point (a time of divergence, speciation) a single lineage a new species extinction (branch ended before present) dashed line (only sketchy evidence of presumed evolutionary relationship)

Evolutionary Trees species 2 species 3 species 1 suspected branching a single lineage; ancestral stock branch point (time of genetic divergence, speciation under way)

A Cladogram shark mammal crocodile bird feathers fur lungs heart

Interpreting a Cladogram

Fig. 19-18a,b, p.312

Constructing a Cladogram

Constructing a Cladogram

Constructing a Cladogram

Constructing a Cladogram

Constructing a Cladogram