The evolutionary history of a species or a group of species Ch 26 Phylogenetics The evolutionary history of a species or a group of species

Binomial Nomenclature Linnaeus Taxonomy: classification Domains>kingdoms>phyla>classes>orders> families: Genera>Species

Canis lupus Order Family Genus Species Felidae Panthera Pantherapardus Fig. 26-4 Order Family Genus Species Felidae Panthera Pantherapardus Taxidea Taxidea taxus Carnivora Mustelidae Lutra lutra Lutra Canis latrans Canidae Canis Canis lupus

Branch point (node) Taxon A Taxon B Sister taxa Taxon C ANCESTRAL Fig. 26-5 Branch point (node) Taxon A Taxon B Sister taxa Taxon C ANCESTRAL LINEAGE Taxon D Taxon E Taxon F Common ancestor of taxa A–F Polytomy

Phylogeny Nodes are ancestors Polytomy: a branch point from which more than two groups emerge and evolutionary relationships are not clear Based on DNA

What we can and cannot learn 1. no indicator of absolute age 2. can show most recent common ancestor 3. time is proportional to lengths of branches 4. cannot assume how much evolutionary change has occurred in a branch 5. Simply pattern of descent

Sorting Homology from Analogy 6. are inferred from morphological and molecular data Convergent evolution: analogy Moles: marsupial and placental Birds and Bats

cladistics Common ancestry is the primary classification system Monophyletic: a taxon is =a clad if it consists of an ancestral species and all its descendents Paraphyletic: a group of ancestral species and some of its descendents Polyphyletic: group which includes taxa with different ancestors

(a) Monophyletic group (clade) (b) Paraphyletic group Fig. 26-10 A A A B Group I B B C C C D D D E E Group II E Group III F F F G G G (a) Monophyletic group (clade) (b) Paraphyletic group (c) Polyphyletic group

Shared ancestral vs derived characters Shared ancestral characteristic: originated in the ancestor of the taxon (vertebrates) Shared derived character: evolutionary novelty unique to a particular clade (hair)

Maximum parsimony and Maximum Likelihood Parsimony: investigate the simplest explanation that is consistent with the facts Morphologically means a parsimonious tree has the fewest events (shared derived) Based on DNA: the fewest base changes Likelihood: assume rates of evolution.complex!!!

(a) Percentage differences between sequences Fig. 26-14 Human Mushroom Tulip Human 30% 40% Mushroom 40% Tulip (a) Percentage differences between sequences 15% 5% 5% 15% 15% 10% 20% 25% Tree 1: More likely Tree 2: Less likely (b) Comparison of possible trees

Molecular Clocks Depends on species Depends on generation time Accumulated mutations Assume certain rate of evolution: neutral theory If most mutations are not harmful then they are not a part of natural selection and have no effect on fitness = a clock

3 Domains Bacteria: prokaryotes related to chloroplasts and mitochondria Archaea: diverse group of bacteria that occupy diverse,unlikely environments Eukarya: true nuclei Much of lifeon Earth has been single celled

EUKARYA BACTERIA ARCHAEA Fig. 26-21 Land plants Dinoflagellates Green algae Forams Ciliates Diatoms Red algae Amoebas Cellular slime molds Euglena Trypanosomes Animals Leishmania Fungi Sulfolobus Green nonsulfur bacteria Thermophiles (Mitochondrion) Spirochetes Halophiles Chlamydia COMMON ANCESTOR OF ALL LIFE Green sulfur bacteria BACTERIA Methanobacterium Cyanobacteria ARCHAEA (Plastids, including chloroplasts)

Horizontal Gene transfer Eukaryotes arose from an endosymbiosis between an early bacterium and archaean Meaning eukaryotes are simultaneously most closely related to both Ring would be better than a tree Try to do 9 on p 555

Fig. 26-22 Bacteria Eukarya Archaea 4 3 2 1 Billions of years ago

Fig. 26-23 Eukarya Bacteria Archaea