1. Warm-Up
Contrast adaptive radiation vs. convergent evolution? Give an example of each.
What is the correct sequence from the most comprehensive to least comprehensive taxon?
In a population of 500 rabbits, 320 are homozygous dominant for brown coat color (BB), 160 are heterozygous (Bb), and 20 are homozygous white (bb).
What are the frequencies of the alleles (B and b)?
What are the frequencies of the different genotypes (BB, Bb, and bb)?

2. Phylogeny and the Tree of Life
Chapter 26
Phylogeny and the Tree of Life

3. What you need to know:
The taxonomic categories and how they indicate relatedness.
How systematics is used to develop phylogenetic trees.
The three domains of life including their similarities and their differences.

4. (evolutionary history)
Systematics: classifying organisms and determining their evolutionary relationships
Taxonomy
(classification)
Systematics
Phylogenetics
(evolutionary history)

5. Tools used to determine evolutionary relationships: Fossils
Morphology (homologous structures)
Molecular evidence (DNA, amino acids)
Who is more closely related?
Animals and fungi are more closely related than either is to plants.

6. Taxonomy: science of classifying and naming organisms
Binomial nomenclature (Genus species)
Naming system developed by Carolus Linnaeus.

7. REMEMBER!!
Dear King Philip Came Over For Good Spaghetti
Dear King Philip Crossed Over Five Great Seas
Dear King Philip Came Over From Germany Stoned
Your own???

8. Phylogenetic Tree
Branching diagram that shows evolutionary history of a group of organisms

10. Simple trees European wildcat Domestic cat South China Tiger
IMAGES FROM: Wikimedia Commons

11. Ancestor of domestic cat and wildcat
European wildcat
Ancestor of all three cats
Tiger

12. Human Gorilla Chimpanzee
IMAGES FROM: Wellcome Images / Wikimedia Commons

13. Extant species
Hypothetical ancestors
Human
Chimpanzee
Root
(common ancestor)
Outgroup
Branch
Gorilla

14. Cladogram
Phylogram
Branch length shows evolutionary change or time (or both)
Branch length does not indicate evolutionary change or time

15. Rooted tree
Unrooted tree
Relationships and the order of events are shown
Only relationships are shown

16. Three possible layouts
Circular (rooted) tree
Unrooted tree
Rooted tree

17. Constructing a phylogenetic tree
A 0 indicates a character is absent; a 1 indicates that a character is present.

18. Branch lengths can represent genetic change

19. Branch lengths can indicate time

20. Build your own tree

21. Living (extant) species
Common ancestor
(fossil)

22. Extant species
Common
ancestor

23. Possible answers

24. Tree 1

25. Tree 2

26. Tree 3

27. Problems

28. Convergent evolution Vertebrate eye Octopus eye Nerve fibres Retina
Blind spot
Optic nerve
Optic nerve
Vertebrate eye
Octopus eye
IMAGE FROM: Caerbannog. Wikimedia Commons

29. different trees are possible
Rhesus monkey
Squid
Bacterium
Tiger
Herring
Snail
Dog
Octopus
Baboon
Coelacanth
Fox
Turbot
Lemur
Chimpanzee
Oak tree
Cat
Redwood tree
Gibbon
Pine tree
Human
With 20 species
8, 200, 794, 532, 637, 891, 559, 375
different trees are possible
Only one is right

30. Human
Bacterium
Coelacanth
Cat
Tiger
Dog
Fox
Baboon
Rhesus monkey
Chimpanzee
Gibbon
Lemur
Herring
Turbot
Snail
Octopus
Squid
Redwood tree
Pine tree
Oak tree

31. Draw a phylogenetic tree based on the data below
Draw a phylogenetic tree based on the data below. Draw hatch marks on the tree to indicate the origin(s) of each of the 6 characters.

32. Answer:

33. Cladogram: diagram that depicts patterns of shared characteristics among taxa
Clade = group of species that includes an ancestral species + all descendents
Shared derived characteristics are used to construct cladograms
Turtle
Leopard
Hair
Amniotic egg
Four walking legs
Hinged jaws
Vertebral column
Salamander
Tuna
Lamprey
Lancelet (outgroup)
Cladogram

34. Monophyletic, paraphyletic, and polyphyletic groups

35. Monophyletic
A valid clade is monophyletic, signifying that it consists of the ancestor species and all its descendants

36. Paraphyletic
A paraphyletic grouping consists of an ancestral species and some, but not all, of the descendants

37. Polyphyletic
A polyphyletic grouping consists of various species that lack a common ancestor

38. Outgroups
An outgroup is a species or group of species that is closely related to the ingroup, the various species being studied
Systematists compare each ingroup species with the outgroup to differentiate between shared derived and shared primitive characteristics
Outgroup comparison assumes that homologies shared by the outgroup and ingroup must be primitive characters that predate the divergence of both groups from a common ancestor
It enables us to focus on characters derived at various branch points in the evolution of a clade

39. Practice
Use the four cladograms below to answer the following questions: (5)
a. Which cladograms have identical topologies (show the same pattern of relationships)?
b. On tree 1, circle two different monophyletic groups.
c. On tree 2, can you circle those same monophyletic groups. If so, do it!
d. On tree 3 circle a paraphyletic group.
E. On tree 4, which organisms are more closely related B and C or C and D. How can you tell?

40. More Practice Answer the questions associated with the following tree:
a. Circle the monophyletic group that includes Mimes & Carnies.
b. Which group(s) are most closely related to Carnies?
c. Are Clowns, Jugglers & Comedians a monophyletic group? If not, who else would need to be included?
d. Who is more closely related to Jugglers: Mimes or Clowns, or are they equally related?
e. What type of trait is “uses face paint” (e.g. shared ancestral, derived, etc.)?

41. Principle of maximum parsimony: use simplest explanation (fewest DNA changes) for tree – “keep it simple”
Molecular clocks: some regions of DNA appear to evolve at constant rates
Estimate date of past evolutionary events
Eg. Origin of HIV infection in humans= 1930’s

42. Tree of Life
3 Domains: Bacteria, Archaea, Eukarya

43. Identification of species
SYSTEMATICS
focuses on
phylogeny
Biological diversity
taxonomy
cladistics
classification
Identification of species D K P C O F G S
Homologous
similarities
fossils
binomial
molecular
Genus, species
morphology