Ch 26 Phylogenetics

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

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

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

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

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

6. 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

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

8. 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

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

10. 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)

11. 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!!!

12. Mushroom Human Tulip 40% 0 30% Human 40% Fig. 26-14 0 Mushroom 0 Tulip (a) Percentage differences between sequences 5% 15% 5% 15% 15% 10% 25% 20% Tree 1: More likely Tree 2: Less likely (b) Comparison of possible trees

13. 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

14. 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

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

16. 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

17. Fig. 26-22 Bacteria Eukarya Archaea 4 3 2 1 0 Billions of years ago

18. Eukarya Fig. 26-23 Bacteria Archaea