2. Fields of Study in Animal Diversity
Phylogeny
The evolutionary history of a species or group of related species.
Systematics
Determining evolutionary relationships of organisms (the study of phylogeny).
Taxonomy
Assigning organisms to different categories based on their evolutionary relationships.
Nomenclature
The science of naming organisms

3. The Kingdoms
How are relationships – evolutionary relationships – determined?
Structure
Breeding behavior
Geographical distribution
Chromosome comparison
Biochemistry
These provide clues to how organism evolved

4. Structure
Many shared physical traits implies species are closely related
Came from a common ancestor:

5. Examples
Lynx and bobcats have similar structure (skeletal) = more similarities than to any other groups
Dandelions and sunflowers = similar flower and fruit structures

6. Conclusion
So what happens if you come across an unknown animal that can retract its claws similar to:
Lions
Tigers
Bobcats
Lynxes?
What family should it belong to?

7. Breeding Behavior
What if two species live in the same area, and are similar in structure?
What else could you do analyze to determine if one species, or two different?
Look at breeding patterns

8. Example 2 species of frog:
Hyla versicolor
Hyla chrysoscelis
During mating season, the males make different sounds to attract females, only mate with females of their own species

9. Geographical distribution
Location of species on Earth helps biologists determine relationships with other species
Similarities between species separated by large distances show common ancestry

10. Example
Many species of finches on the Galapagos Islands off the coast of South America

12. Example How did the birds get there?
Some members of species of finches from South America reached the Galapagos Islands
These finches spread into different habitats and evolved into diverse species…but kept genetic similarities

13. Chromosome Comparison
Number and structure of chromosomes

14. Example
The following all look different, grow in separate climates, however they all have nearly identical chromosomal structure!!
Cauliflower
Cabbage
Kale
Broccoli

15. Example
Humans, gorillas and chimpanzees have chromosomes with similar appearances

16. Chromosomal Comparisons

17. Chromosomes of Unrelated Species
Bacteria
Other Species

18. Conclusion
Chromosomal similarities suggest a common ancestry

19. Biochemistry
Biochemical – DNA – evidence shows closely related species have similar DNA sequences
Similar proteins
Each specie’s DNA has a unique sequence and order:
DNA is located on a small section of the chromosome

21. Example
≠ ║ ║

22. Conclusion
The more similarities two species have between the sequence/order of their DNA molecule, the more closely related

23. Unexpected Family Tree
Currently, systematists use
Structural, biochemical, fossil, and molecular comparisons to infer evolutionary relationships
You
Your Cousin!

24. Morphological and Molecular Homologies
In general, organisms that share very similar structures, breeding patterns or similar DNA sequences
Are likely to be more closely related than organisms with vastly different structures or sequences.
Not always true! Analogy vs. Homology

25. Homology
Homologous Structures – structures in different species that are similar because of common ancestry.

26. Analogy
Analogous Structures – similarity in structures due to adaptations from similar evolutionary pressures (convergent evolution) and not a common ancestor.

27. Australian Mole –marsupial mammal
Convergent evolution occurs when similar environmental pressures and natural selection
Produce similar (analogous) adaptations in organisms from different evolutionary lineages
Australian Mole –marsupial mammal
North American Mole – placental mammal

28. Sorting Homology from Analogy
A potential misconception in constructing a phylogeny
Is similarity due to convergent evolution, called analogy, rather than shared ancestry
Ex: Humans, gorillas, and ravens have the ability to problem-solve, and are highly intelligent. Humans and gorillas share ancestry: homology. Ravens are in a separate phylum (birds), so developed their intelligence separately from humans.

29. Linking Classification and Phylogeny
Systematists depict evolutionary relationships
In branching phylogenetic trees

30. Each branch point
Represents the divergence of two species

31. “Deeper” branch points
Represent progressively greater amounts of divergence

32. “KLADOS” = Greek word meaning “BRANCH” or “SPROUT”
Cladogram - a shows pattern of shared, inherited characteristics; a “graphic organizer” based on measurable traits and not evolutionary relationships.

33. Cladogram for Transportation
Wheels are the most ancestral (oldest).
Wings are the most derived (newest).

34. Construct a Cladogram for Us!

35. Gorilla
Four limbs
Fur
No tail

36. Tiger
Four limbs
Fur
Tail

37. Lizard
Four limbs
Tail

38. Fish
Tail

39. Chimpanzee
Four limbs
Fur
No tail

40. Clade With 4 Limbs

41. Clade With Fur

42. Clade With No Tail

43. Characteristics (Traits) for Constructing this Cladogram
Tail is the most ancestral
Four limbs is the oldest derived trait
Fur is a later derived trait
Loss of tail is the most derived trait

44. One Possible Cladogram
Four Limbs

45. Where’s the Tail?
How do we know the gorilla and chimpanzee have lost their tail?
Sometimes cladists must compare embryological development and internal anatomy to determine relatedness.
May not be exactly the same structures.

46. Coccyx- Primate Vestigial Tails
Human Pelvic Girdle
Gorilla Pelvic Girdle
Vestigial Structure - historical remnants of a structure that has little or no use in a modern organism but had a function in ancestors.

47. A Vertebrate Cladogram
Vertebrae
Lancelet
Outgroup

48. Ans: Birds Mammals Reptile Feathers Amphibian Fur Fish Endothermic
Four Limbs
Amniotic Egg
Endothermic
Fur
Feathers
Vertebrae
Lancelet
Outgroup
What is the shared primitive character for this clade?
Ans:

49. Birds
Mammals
Reptile
Amphibian
Fish
Four Limbs
Amniotic Egg
Endothermic
Fur
Feathers
Vertebrae
Lancelet
Outgroup
What is the shared derived character for amphibians, reptiles, birds & mammals?
Ans: Four Limbs
For reptiles, birds & mammals?
Ans: Amniotic Egg

50. Phylogenetic Trees and Timing
A cladogram is not a phylogenetic tree; may need more information (fossils, molecular systemics, etc.).
Any chronology represented by the branching pattern of a phylogenetic tree
Is relative rather than absolute in terms of representing the timing of divergences.

51. Phylograms
In a phylogram:
The length of a branch reflects the number of genetic changes that have taken place in a particular DNA or RNA sequence in that lineage.
A phylogram of homologous hedgehog genes.
Outgroup

52. Ultrametric Trees
In an ultrametric tree:
The branching pattern is the same as in a phylogram, but all the branches that can be traced from the common ancestor to the present are of equal length.
Outgroup

53. A Rule about Phylogenetic Trees
William of Ockham – 14th Cent. English philosopher, stated that, when all qualities of hypotheses are equal, the simplest explanation for a phenomenon is usually correct; Occam’s Razor: "entities must not be multiplied beyond necessity" (entia non sunt multiplicanda praeter necessitatem).
Parsimony – stingy, economical, fewest complications.