1. Evidence for Evolution
Biogeography
Fossil Records
Comparative anatomy
Comparative embryology
Molecular biology
Evolution is consistent with all scientific observations!

2. Biogeography Species are most closely related to those near them
Rain forests in different parts of the world have very different species
Species tend to be very similar to the fossils found in there area – but with some changes

3. Fossil Records
The age of different fossils matches what we would expect
I.e. we find that brain size has increased over time

4. Fossils Con.
Oldest vertebrate fossils are fish, then amphibians, reptiles, mammals and birds
Many hypothesized intermediate species have been found, i.e. Artie, Lucy, fish with legs

5. Comparative Anatomy
The anatomies of related species are similar, even if they are used differently
i.e. bones of humans, cats whales and bats are similar
It seems unlikely a designer would make a bat's wing similar to a whale's fin
Homologous Structures

6. Vestigial Organs Leftover body parts that do not help a species
i.e. whales still have pelvises and remnants of leg bones
These structures serve no purpose in the modern animal

7. Comparative Embryology
Similar species develop in very similar ways
Especially early in development, before lots of specialization has occurred

8. Molecular Biology
Closely related species are closely related in their genetic codes
Also supports idea that all species are related- all species share DNA and some proteins

9. The “Theory” of Evolution
The closely related nature of all life is really not debatable
Natural selection is really the theory
Well documented and thoroughly supported- like the “Theory” of Gravity

10. Macroevolution and Speciation
Microevolution explains how populations can change over time
But how do new species or other taxonomic groups arise?

11. Geographic Speciation
The formation of new species usually occurs when 2 populations are separated and evolve differently
Eventually the species have changed so much that they can no longer reproduce

12. Reproductive Isolation
A byproduct of genetic differences
Different:
Mating behaviors
Mating times
Mating locations
Mating “structures”
Gametes
Or offspring that are infertile- no mixing of genes

13. Reproductive Isolation  Speciation
With no gene flow between the population, they become more and more different
This usually takes thousands to millions of years

14. Exception - Polyploidy
Occasionally plants end up combing their full genomes (instead of half) leading to a doubling of the chromosome #
Instantly forms a new species
Extremely significant in plant evolution

15. Biological Definition of Species
2 populations that cannot naturally mix genes
Due to any of the reproductive isolation methods
Not a perfect system

16. Evolution is Always Occurring
Usually just slowly
Bacteria and viruses change over time – we must constantly come up with new antibiotics and new vaccines

18. Changing Environments Accelerate Evolution
New habitats open up opportunities for evolution
Leads to adaptive radiations – where many groups evolve from a single ancestor
i.e. after the fall of dinosaurs- many mammal groups evolved

19. One Major Change leads to many New Adaptive Radiations
Imagine the first species that could breath in air
Many new species would quickly evolve – lots of territories to take over!
Then evolution would slow down once there is competition for space

20. Extinction
Is the norm
Most species go extinct- but new ones survive
There have been at least 5 major mass extinctions

22. Phylogeny and Taxonomy
Tracing Evolutionary History

23. Phylogenetic Trees
Show how each species is related to other closely related species
Shows common ancestors
Use fossils and other evidence to reconstruct an organisms history

25. Monophyletic Taxa
We want to trace species to a single common ancestor for each taxa, and include every species that descended from that ancestor
i.e. all mammals can be traced to a single mammalian ancestor

26. Monophyletic Taxa
Includes a species and every single one of it’s descendents
I.e. Primates – include the primate ancestor and all of it’s descendents (including us!)

27. NOT a Monophyletic Taxa
Plants and Animals (because fungi and other species share the same common ancestor)
Grouping all monkeys/apes together BUT not including humans
Reptiles (birds share the same common ancestor and should be included in reptiles!)

28. Comparing fossils/anatomies/structure/devel opment
How Do We Make Trees?
Comparing DNA
Comparing fossils/anatomies/structure/devel opment

29. Molecular Biology Provides Great Evidence for Classification
Similarities in DNA sequence
Comparison of proteins
The more DNA changes/protein differences, the less closely related the species

30. Molecular Analysis Advantages Disadvantages
Most accurate
Large numbers of traits/proteins to analyze
Allows us to differentiate between closely related species that appear very similar
Individuals of the same species differ in DNA
Can be confusing

31. DNA Base Pair Differences1 2 3 4 5 x 10 20 30 40

33. 1 2 3 4 5 x 10 20 30 40

34. Practice (# of base pair differences in a gene)
Cat
Dog
Wolf
Skunk
Otter x 28 26 15 14 2 10 9 8

35. Phylogenetic Tree
Time

37. Homology/Anatomy Analysis
Find an adaptation that is present in one lineage, but not in another
The phylogenetic tree branches when these new features evolved

38. Cladistic Tables Different Species 1 2 3 4 5 Character A? Character B?
Yes
Character B? No
Character C?
Character D?
Character E?

40. 1 2 3 4 5 Character A? Character B? Character C? Character D?
Yes
Character B? No
Character C?
Character D?
Character E?

41. Practice Reptiles Plants Mammals Bacteria Amphibians Y N DNA
Organelles
Cell Walls
Amnion
Hair
Reptiles Y N
Plants
Mammals
Bacteria
Amphibians

42. Ancestral reptile
Time
Ancestral fish
Ancestral animal

44. Anatomy Analysis Homologous structures show relationships
Advantages
Disadvantages
Homologous structures show relationships
Allows us to determine when changes occurred (using fossils)
Best way to analyze extinct species
Analogous structures do not and can be confused
Not all species leave fossils
The fossils we have collected are incomplete

45. Homology vs. Analogy
Homology means two features are similar due to ancestry
Wings in bats, arms in humans, fins in whales
Called homologous structures
Caused by divergent evolution
Analogy is when two organisms have similar features but are not closely related
Wings in bats and birds
Caused by convergent evolution
Evolved the same solution

46. Embryology Analysis Advantages Disadvantages
Allows us to see similarities even when adults of the species look very different
I.e. reptiles and birds look more closely related
Often similarities are lost later in development
i.e. We have gills early on in development

47. We did not evolve from chimpanzees!