1. Evolution
Species change over time, in part because of how they interact with their environment (ecology).

2. A. Evolution and Common Ancestry
Darwin
A. Evolution and Common Ancestry
Concludes that species change over time, diverging from one another and their common ancestors as they adapt to new environments
Plate from The Origin of Species, 1859
1837 notebook

3. Darwin
A. Evolution and Common Ancestry
As a consequence of:
- stratigraphic patterns in the fossil record

4. A. Evolution and Common Ancestry As a consequence of:
Darwin
A. Evolution and Common Ancestry
As a consequence of:
- stratigraphic patterns in the fossil record
- evidence from morphology
Homologous Structures:
Same parts, but different uses in different environments
(correlated pattern)

5. A. Evolution and Common Ancestry As a consequence of:
Darwin
A. Evolution and Common Ancestry
As a consequence of:
- stratigraphic patterns in the fossil record
- evidence from morphology
Analogous Structures:
Different parts, but same uses in same environment
(correlated pattern)

6. A. Evolution and Common Ancestry As a consequence of:
Darwin
A. Evolution and Common Ancestry
As a consequence of:
- stratigraphic patterns in the fossil record
- evidence from morphology
Whale embryo
w/leg buds
Vestigial and embryonic Structures:
No used in one species but functional in others
Haeckel (after Darwin)

7. A. Evolution and Common Ancestry As a consequence of:
Darwin
A. Evolution and Common Ancestry
As a consequence of:
- stratigraphic patterns in the fossil record
- evidence from morphology
- evidence from biogeography
Community Convergence:
In similar environments, unrelated organisms play parallel roles and converge morphologically and ecologically

8. A. Evolution and Common Ancestry As a consequence of:
Darwin
A. Evolution and Common Ancestry
As a consequence of:
- stratigraphic patterns in the fossil record
- evidence from morphology
- evidence from biogeography
Island Communities:
In isolated environments, colonists change in response to new conditions

9. Darwin
A. Evolution and Common Ancestry
B. Mechanism of Change: Natural Selection
P1: All populations have the capacity to ‘over-reproduce’
P2: Resources are finite
C: There will be a “struggle for existence”… most offspring born will die before reaching reproductive age.

10. Darwin
A. Evolution and Common Ancestry
B. Mechanism of Change: Natural Selection
P1: All populations have the capacity to ‘over-reproduce’
P2: Resources are finite
C: There will be a “struggle for existence”… most offspring born will die before reaching reproductive age.
P3: Organisms in a population vary, and some of this variation is heritable

11. Darwin
A. Evolution and Common Ancestry
B. Mechanism of Change: Natural Selection
P1: All populations have the capacity to ‘over-reproduce’
P2: Resources are finite
C: There will be a “struggle for existence”… most offspring born will die before reaching reproductive age.
P3: Organisms in a population vary, and some of this variation is heritable
C2: As a result of this variation, some organisms will be more likely to survive and reproduce than others – there will be differential reproductive success.
P3: Organisms in a population vary, and some of this variation is heritable

12. Darwin
A. Evolution and Common Ancestry
B. Mechanism of Change: Natural Selection
P1: All populations have the capacity to ‘over-reproduce’
P2: Resources are finite
C: There will be a “struggle for existence”… most offspring born will die before reaching reproductive age.
P3: Organisms in a population vary, and some of this variation is heritable
C2: As a result of this variation, some organisms will be more likely to survive and reproduce than others – there will be differential reproductive success.
C3: The population changes through time, as adaptive traits accumulate in the population.
P3: Organisms in a population vary, and some of this variation is heritable

13. Darwin
A. Evolution and Common Ancestry
B. Mechanism of Change: Natural Selection
P1: All populations have the capacity to ‘over-reproduce’
P2: Resources are finite
C: There will be a “struggle for existence”… most offspring born will die before reaching reproductive age.
P3: Organisms in a population vary, and some of this variation is heritable
C2: As a result of this variation, some organisms will be more likely to survive and reproduce than others – there will be differential reproductive success.
C3: The population changes through time, as adaptive traits accumulate in the population.
Corollary: Two populations, isolated in different environments, will diverge from one another as they adapt to their own environments. Eventually, these populations may become so different from one another that they are different species.
P3: Organisms in a population vary, and some of this variation is heritable

14. ? I. Darwin Sources of Variation Agents of Change Natural Selection

15. Sources of Variation Agents of Change Mutation Natural Selection
Darwin
Genetics
Sources of Variation Agents of Change
Mutation Natural Selection
Recombination Mutation
- crossing over
- independent assortment
VARIATION
Units of heredity (genes) don’t blend together; they are ‘particulate’ and are passed in new combinations to offspring.
In a diploid species, each parent makes 2n combinations of chromosomes in their gametes, without accounting for crossing-over!

16. Population Genetics and The Modern Synthesis A. Model
Darwin
Genetics
Population Genetics and The Modern Synthesis
A. Model
Sources of Variation Agents of Change
Mutation Natural Selection
Recombination Mutation
- crossing over Drift
- independent assortment Migration Non-Random Mating
VARIATION
Rates of mutation are low; mutation is important as a source of new genes, but doesn’t change frequencies much. Selection and drift are major agents of change.

17. Darwin
Genetics
Population Genetics and The Modern Synthesis
A. Model
B. Drift
- two patterns related to population size

18. Darwin
Genetics
Population Genetics and The Modern Synthesis
A. Model
B. Drift
- two patterns related to population size

19. - “Genetic Bottleneck”
If a population crashes (perhaps as the result of a plague) there will be both selection and drift. There will be selection for those resistant to the disease (and correlated selection for genes close to the genes conferring resistance), but there will also be drift at other loci simply by reducing the size of the breeding population.
Cheetah have very low genetic diversity, suggesting a severe bottleneck in the past. They can even exchange skin grafts without rejection…
European Bison, hunted to 12 individuals, now number over 1000.
Fell to 100’s in the 1800s, now in the 100,000’s

20. - “Founder Effect” and Huntington’s Chorea
HC is a neurodegenerative disorder caused by an autosomal lethal dominant allele.
The fishing villages around Lake Maracaibo in Venezuela have the highest incidence of Huntington’s Chorea in the world, approaching 50% in some communities.
By comparing pedigrees, she traced the incidence to a single woman who arrived 200 years ago. When the population was small, she had 10 children who survived and reproduced. Folks with HC now trace their ancestry to this lineage.

21. Darwin
Genetics
Population Genetics and The Modern Synthesis
Modern Evolutionary Theory
A. Peripatric Speciation

22. Population Genetics and The Modern Synthesis
Darwin
Genetics
Population Genetics and The Modern Synthesis
Modern Evolutionary Theory
A. Peripatric Speciation
B. Punctuated Equilibrium
Niles Eldridge
Stephen J. Gould

23. B. Punctuated Equilibrium – Eldridge and Gould
1. Consider a large, well-adapted population
VARIATION
TIME

24. B. Punctuated Equilibrium – Eldridge and Gould
1. Consider a large, well-adapted population
Effects of Selection and Drift are small - little change over time
VARIATION
TIME

25. B. Punctuated Equilibrium – Eldridge and Gould
2. There are always small sub-populations "budding off" along the periphery of a species range...
VARIATION
TIME

26. X X X B. Punctuated Equilibrium – Eldridge and Gould
2. Most will go extinct, but some may survive...
VARIATION X X X
TIME

27. X X X B. Punctuated Equilibrium – Eldridge and Gould
2. These surviving populations will initially be small, and in a new environment...so the effects of Selection and Drift should be strong...
VARIATION X X X
TIME

28. X X X B. Punctuated Equilibrium – Eldridge and Gould
3. These populations will change rapidly in response...
VARIATION X X X
TIME

29. X X X B. Punctuated Equilibrium – Eldridge and Gould
3. These populations will change rapidly in response... and as they adapt (in response to selection), their populations should increase in size (because of increasing reproductive success, by definition).
VARIATION X X X
TIME

30. X X X B. Punctuated Equilibrium – Eldridge and Gould
3. As population increases in size, effects of drift decline... and as a population becomes better adapted, the effects of selection decline... so the rate of evolutionary change declines...
VARIATION X X X
TIME

31. X X X B. Punctuated Equilibrium – Eldridge and Gould
4. And we have large, well-adapted populations that will remain static as long as the environment is stable...
VARIATION X X X
TIME

32. X X X B. Punctuated Equilibrium – Eldridge and Gould
5. Since small, short-lived populations are less likely to leave a fossil, the fossil record can appear 'discontinuous' or 'imperfect'
VARIATION X X X
TIME

33. X X X B. Punctuated Equilibrium – Eldridge and Gould
5. Large pop's may leave a fossil....
VARIATION X X X
TIME

34. X X X B. Punctuated Equilibrium – Eldridge and Gould
5. Small, short-lived populations probably won't...
VARIATION X X X
TIME

35. X X X B. Punctuated Equilibrium – Eldridge and Gould
6. So, the discontinuity in the fossil record is an expected result of our modern understanding of how evolution and speciation occur...
VARIATION X X X
TIME

36. X X X B. Punctuated Equilibrium – Eldridge and Gould
6. both in time (as we see), and in SPACE (as changing populations are probably NOT in same place as ancestral species).
VARIATION X X X
TIME

37. Population Genetics and The Modern Synthesis
Darwin
Genetics
Population Genetics and The Modern Synthesis
Modern Evolutionary Theory
A. Peripatric Speciation
B. Punctuated Equilibrium
C. Genes and Development: “Evo-Devo”
…explain changes like this?
Can changes like this….

38. C. Genes and Development: "Evo-Devo"
…explain changes like this?
Can changes like this….
Differences correlate with what they make (different proteins make them different colors)
Differences don’t correlate with what they make; they are pretty much the same stuff, just in a different shape.

39. C. Genes and Development: "Evo-Devo"

40. C. Evo-Devo – the influence of regulatory genes

41. Without Fish
With Fish
Antennules detect chemicals secreted by predatory fish
Stimulate release of dopamine in the brain
Brain releases juvenile hormone (growth hormone in inverts)
Growth of particular body parts continues, creating a sharp “helmet” and longer “spine” that reduce predation.
Selection for an inducible developmental pathway

42. Modern Evolutionary Theory A. Peripatric Speciation
B. Punctuated Equilibrium
C. Genes and Development: “Evo-Devo”
D. Model
Sources of Variation Agents of Change
Mutation Natural Selection
Recombination Drift
- crossing over Mutation
- independent assortment Migration
Non-random Mating
VARIATION D E V L O P M N T