A.P. Biology Mr. Tesoro

1. A.P. Biology Mr. Tesoro • Homework Reminder: • Lab Report on Population Genetics and Evolution is due Wed., April 2, 2014 • Test on Evolution Thurs., Apr. 3, 3014 Do Now: What is the best evidence a scientist can use to classify a newly-found species?

2. Aim: What is Phylogeny? 0

3. Phylogeny is the evolutionary history of a species or group of related species Taxonomy is the ordered division and naming of organisms

4. 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 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

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

6. A taxonomic unit at any level of hierarchy is called a taxon

7. Linking Classification and Phylogeny Systematists depict evolutionary relationships in branching phylogenetic trees

8. Figure 20.4 1 2 Order Family Genus Species Panthera pardus (leopard) Felidae Panthera Taxidea taxus (American badger) Taxidea Carnivora Mustelidae Lutra lutra (European otter) Lutra Canis latrans (coyote) Canidae Canis Canis lupus (gray wolf)

9. A phylogenetic tree represents a hypothesis about evolutionary relationships Each branch point represents the divergence of two taxa from a common ancestor Sister taxaare groups that share an immediate common ancestor

10. 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 polytomyis a branch from which more than two groups emerge

11. Figure 20.5 1 2 3 4 5 Branch point: where lineages diverge Taxon A Taxon B Sister taxa Taxon C Taxon D Taxon E ANCESTRAL LINEAGE Taxon F 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.

12. 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

13. Cladistics Cladisticsclassifies organisms by common descent A cladeis 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 clades A valid clade is monophyletic, signifying that it consists of the ancestor species and all its descendants

14. Figure 20.10a 1 (a) Monophyletic group (clade) A B Group I C D E F G

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

16. Inferring Phylogenies Using Derived Characters When inferring evolutionary relationships, it is useful to know in which clade a shared derived character first appeared 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

17. Figure 20.11 TAXA Lancelet (outgroup) Lancelet (outgroup) Lamprey Leopard Lamprey Turtle Bass Frog Vertebral column (backbone) Bass 0 1 1 1 1 1 Vertebral column 1 1 Hinged jaws 0 1 0 1 Frog Hinged jaws Four walking legs CHARACTERS 0 1 1 0 0 1 Turtle Four walking legs Amnion 0 0 0 0 1 1 Amnion Leopard 1 0 0 0 Hair 0 0 Hair (a) Character table (b) Phylogenetic tree

18. Figure 20.11a TAXA Lancelet (outgroup) Lamprey Leopard Turtle Bass Frog Vertebral column (backbone) 0 1 1 1 1 1 Hinged jaws 1 1 0 1 0 1 Four walking legs 0 0 1 0 1 1 CHARACTERS 0 1 1 0 0 0 Amnion 0 0 1 0 0 0 Hair (a) Character table

19. Figure 20.11b Lancelet (outgroup) Lamprey Bass Vertebral column Frog Hinged jaws Turtle Four walking legs Amnion Leopard Hair (b) Phylogenetic tree

20. An outgroupis 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

21. 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 In other trees, branch length can represent chronological time, and branching points can be determined from the fossil record

22. Figure 20.12 Drosophila Lancelet Zebrafish Frog Chicken Human Mouse

23. Figure 20.13 Drosophila Lancelet Zebrafish Frog Chicken Human Mouse PALEOZOIC MESOZOIC CENOZOIC 251 542 65.5 Present Millions of years ago

24. Phylogenetic Trees as Hypotheses The best hypotheses for phylogenetic trees fit the most data: morphological, molecular, and fossil Phylogenetic hypotheses are modified when new evidence arises

25. 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

26. Animation: Class Schemes Right click slide / Select play