1. Varieties of life forms
Figure 1.4C-F

2. Evolution explains the unity and diversity of life
Charles Darwin synthesized the Theory of Evolution by natural selection
Theory vs hypothesis
Evolution is the core theme of biology
Who was Darwin? Biologist at age 22, taken on 5 yr voyage to explore. Europeans realized the economic potential of natural resources, wanted to “discover” and exploit them worldwide.
1859 published On the Origin of Species. Presented theory of natural selection
Radical change in std western thinking.
religions stated age of earth as 6K, based on Bible
Aristotle held that species are fixed, unchanging
Evolution theory explained lots of different observtns, simplified what appeared to be complex systems Th4, THEORY, not just sgl hypothesis.
Diversity of life explained. A reason for all the types of animals, why some finches have beaks of this shape and others are different.
Unifying theory – many orgs descended from a common ancestor.
Wallace also conceived idea,based on observtn sent his paper to Darwin for his comments. So Darwin hurried to publish his own work and get credit.
Figure 1.6A

3. The voyage of the Beagle
Great Britain
Europe
North America
Pacific Ocean
Atlantic Ocean
Africa
Galápagos Islands
Equator
South America
Australia
Andes
Cape of Good Hope
Tasmania
Cape Horn
New Zealand
Tierra del Fuego
Figure 13.1B

4. Prevalent ideas at Darwin’s time
species are fixed
Earth is about 6,ooo yrs old
Evidence for evolution. Current thought, very solid in western culture: fixed species. Also, literal interp of Bible and religious bks, earth is 6K old.
Fossils indicated this maybe wrong, that earth and life were much older.

5. New ideas proposed
Fossils indicated the earth was very old
Charles Lyell, a geologist, argued that land forms changed constantly.
Jean- Babtist Lamarck proposed that organisms changed and these changes were passed to progeny.

6. Darwin became convinced that the Earth was old and continually changing
Mex. marine snail shells on high mtns
He concluded that living things also change, or evolve over generations
He also stated that living species descended from earlier life-forms: descent with modification

7. Darwin proposed natural selection as the mechanism of evolution
Darwin observed that
organisms produce more offspring than the environment can support
organisms vary in many characteristics
these variations can be inherited
He concluded that living things also change, or evolve over generations
He also stated that living species descended from earlier life-forms: descent with modification

8. natural selection explains the mechanism of evolution
(1) Population with varied inherited traits
Pesticide-resistant insects
Antibiotic-resistant bacteria
(2) Elimination of individuals with certain traits
Figure 1.6B
(3) Reproduction of survivors

9. Natural selection is the editing mechanism
Evolution happens when populations of organisms with inherited variations are exposed to environmental factors that favor the reproductive success of some individuals over others
Natural selection is the editing mechanism
Evolution is based on adaptations
Figure 1.6C

10. Fossils provide strong evidence for evolution
Hominid skull
Petrified trees
Figure 13.2A, B

11. Fossilized organic matter in a leaf
Ammonite casts
Fossilized organic matter in a leaf
Figure 13.2C, D

12. Scorpion in amber
“Ice Man”
acid bogs
Figure 13.2E, F

13. Mammoth tusks
Figure 13.2x4

14. fossils show that organisms have appeared in a historical sequence
Many fossils link early extinct species with species living today
hind leg bones of fossil whales
Figure 13.2G, H

15. Other evidence for evolution
Biogeography
Comparative anatomy
Comparative embryology
Biogeography- where populations are distributed
Comparative anatomy- Same strictures different looks (homologous versus analogous)
Comparative embryology- when eggs are first fertilized they look the same and they take a long time to develop
Human
Cat
Whale
Bat
Figure 13.3A

16. Molecular biology - protein “clocks”
Human
Rhesus monkey
Mouse
Chicken
Frog
Lamprey
Last common ancestor lived 26 million years ago (MYA), based on fossil evidence
80 MYA
275 MYA
Y-Axis (vertical) shows the differences in protein differences between humans. by the protein we are able to tell relatively when this species "showed up" in evolutionary time
330 MYA
450 MYA
Figure 13.3B

17. Populations are the units of evolution
Evolution DOES NOT happen within one generation of one individual organism within a species. It happens over time in a population.
Figure 13.6

18. gene pool, microevolution Four agents of evolution
What is evolving?
gene pool, microevolution
Four agents of evolution
3. Types of natural selection
A. Forces that create new variants 1. Mutation 2. Gene flow (migration) B. Forces that lead to biased transmission of alleles between generations 1. Genetic drift 2. Natural selection
types of natural selection

19. Populations are the units of evolution
A population is a group of interbreeding individuals
A species is a group of populations whose individuals can interbreed and produce fertile offspring
Important definition/concepts
Figure 13.6

20. What is evolving?
gene pool = total collection of genes in a population at any one time
Microevolution is a change in the relative frequencies of alleles in a gene pool

21. Four agents of microevolution
1. Mutation changes alleles
2. Genetic drift = random changes in allele frequency
Bottleneck
Founder effect
In biology, a mutation is a permanent alteration of the nucleotide sequence of the genome of an organism, virus, or extrachromosomal DNA or other genetic elements.

22. Genetic drift - effects of population size:
LARGE POPULATION = 10,000
SMALL POPULATION = 10
1,000
10,000 1 10
allele frequency =
= 10%
allele frequency =
= 10%
50% of population survives,
including 450 allele carriers
50% of population survives,
with no allele carrier among
them
Figure: FG17-05
Title:
Genetic drift.
Caption:
a. In a hypothetical population of 10,000 individuals, 1 in 10 carries a given allele. The population loses half its members to a disease, including 550 individuals who carried the allele. The frequency of the allele in the population thus drops from 10 percent to 9 percent. b. A population of 10 with the same allele frequency likewise loses half its members to a disease. Because the one member of the population who carried the allele is not a survivor, the frequency of the allele in the population drops from 10 percent to zero. 5
450
5,000
allele frequency =
= 0%
allele frequency =
= 9%
little change in allele frequency
(no alleles lost)
dramatic change in allele frequency
(potential to lose one allele)

23. Bottleneck effect Founder effect
Bottleneck effect- sharp lowering of a population's genepool due to environmental or human caused change
Founder effects A founder effect occurs when a new colony is started by a few members of the original population. This small population size means that the colony may have:
reduced genetic variation from the original population.
a non-random sample of the genes in the original population.
Figure 13.11B, C

24. Natural selection leads to differential reproductive success
Gene flow can change a gene pool due to the movement of genes into or out of a population
ex. Migration
Natural selection leads to differential reproductive success
Nonrandom mating changes genotype frequency
but not allele frequency.

25. Natural selection
- results in the accumulation of traits that adapt a population to its environment
- the only agent of evolution that results in adaptation.

26. What is an organism’s evolutionary fitness?
Darwinian fitness is an individual’s contribution to the gene pool of the next generation compared to other individuals; i.e., number of progeny
Production of fertile offspring is the only score that counts in natural selection

27. There are three general outcomes of natural selection
Original population
Frequency of individuals
Phenotypes (fur color)
Original population
Evolved population
Stabilizing selection
Directional selection
Diversifying selection
Figure 13.19

28. 80 beak depth 1976 60 40 Number of individuals Average beak depth,20
Average
beak depth,
1978
Figure: FG17-09
Title:
Who survives in a drought?
Caption:
sharp focus in 1977, when a tiny Galapagos is-land, Daphne Major, suffered a severe drought. Rain that normally begins in January and lasts through July scarcely came at all that year. This was a disaster for the island's two species of finches; in January 1977 there were 1,300 of them, but by December the number had plunged to fewer than 300. Daphne's medium-sized ground finch, Geospiza fortis, lost 85 percent of its population in this calamity. The staple of this bird's diet is plant A large percentage of the population of Geospiza fortis died on a Galapagos Island, Daphne Major, during a drought in Peter Grant observed in 1978 that individuals who survived the drought had a greater average beak depth than average individuals surveyed before the drought, in 1976.Individuals with larger beaks were better able to crack open the large, tough seeds that were available during the drought. The offspring of the survivors likewise had larger average beak size than did the population before the drought. Thus, evolution through natural selection was observed in just a few years on the island.
1978 5 6 7 8 9 10 11 12 13 14
Beak depth (mm)
Shift of average beak
depth during drought

29. Natural selection tends to reduce variability in populations.20 70
Infant
deaths
Infant
births 60 15 50
Percent
of infant
deaths
Percent of
births in
population 40 10 30 20 5
Figure: FG17-11
Title:
Stabilizing selection: human birth weights and infant mortality.
Caption:
Note that infant deaths are more prevalent at the upper and lower extremes of infant birth weights. 10 2 3 4 5 6 7 8 8 8 9 10 11
Birth weight in pounds
Natural selection tends to reduce variability in populations.

30. Why doesn’t natural selection eliminate all genetic variation in populations?
The diploid condition preserves variation by “hiding” recessive alleles (Bb)
Balanced polymorphism (2+ phenotypes stable in population) may result from:
a. heterozygote advantage Aa > aa and AA
b. frequency-dependent selection
c. variation of environment for a population

31. Many populations exhibit polymorphism and geographic variation
Figure 13.13

32. Not all genetic variation may be subject to natural selection
3. Some variations may be neutral, providing no apparent advantage or disadvantage
Example: human fingerprint patterns
Figure 13.16

33. Endangered species often have reduced variation
Low genetic variability may reduce their capacity to survive as humans continue to alter the environment
cheetah populations have extreme genetic uniformity
Figure 13.17

34. Why do male and female animals differ in appearance?
Sexual selection leads to the evolution of secondary sexual characteristics
Sexual selection may produce sexual dimorphism
Figure 13.20A, B

35. Natural selection cannot fashion perfect organisms
This is due to:
historical constraints
adaptive compromises
chance events
availability of variations

36. What is a species? appearance alone does not always define a species
Example: eastern and western meadowlarks
Figure 14.1A

37. What is a species?
Naturally interbreeding populations
- potentially interbreeding
- reproductively isolated from other species
What about asexually reproducing organisms?
Extinct species?
Shy species?

38. When does speciation occur?
MECHANISMS OF SPECIATION
When does speciation occur?
When geographically isolated, species evolution may occur
gene pool then changes to cause reproductive isolation
= allopatric speciation
Figure 14.3

39. A ring species may illustrate the process of speciation1
OREGON
POPULATION
Sierra Nevada 2
Yellow- blotched
Yellow- eyed
INLAND POPULATIONS
COASTAL POPULATIONS
Gap in ring
Large- blotched
Monterey 3
Figure 14.1C

40. Reproductive barriers between species
Habitat - different locations
Timing - mating, flowering
Behavioral - mating rituals, no attraction
Mechanical - structural differences
Gametic - fail to unite
Hybrid weak or infertile

41. Hybrid sterility is one type of postzygotic barrier
A horse and a donkey may produce a hybrid offspring, a mule
Mules are sterile
Figure 14.2C

42. Sympatric speciation
No geographical isolation
Mutation creates reproductive isolation
Polyploidization
Hybridization

43. When does speciation occur?
Specialists - Galapagos finches
Generalists - horseshoe crabs, cockroaches
New environments
- ecological niche

44. Adaptive radiation on an island chain
- specialization for different niches 1
Species A from mainland 2 B A B 3 B B 4 C C C C D C D 5
Figure 14.4B

45. Common ancestor from South America mainland
Cactus ground finch
Small tree finch
Medium tree finch
Woodpecker finch
Medium ground finch
Small ground finch
Large cactus ground finch
Vegetarian finch
Large tree finch
Mangrove finch
Green warbler finch
Gray warbler finch
Large ground finch
Sharp-beaked ground finch
Seed eaters
Cactus flower eaters
Bud eaters
Insect eaters
Ground finches
Tree finches
Warbler finches
Common ancestor from South America mainland
Figure 15.9

46. No predestined goal of evolution
Figure 15.8

47. Continental drift has played a major role in macroevolution
Continental drift is the slow, steady movement of Earth’s crustal plates on the hot mantle
Eurasian Plate
North American Plate
African Plate
Pacific Plate
Nazca Plate
Split developing
South American Plate
Indo-Australian Plate
Antarctic Plate
Edge of one plate being pushed over edge of neighboring plate (zones of violent geologic events)
Figure 15.3A

48. influenced the distribution of organisms
CENOZOIC
Eurasia
North America
Africa
India
Continental mergers triggered extinctions
Separation of continents caused the isolation and diversification of organisms
South America
Australia
Antarctica
Laurasia
Millions of years ago
MESOZOIC
Gondwana
Pangaea
PALEOZOIC
Figure 15.3B

49. Speciation - how much change is needed?
Gradual vs. jerky
Evidence:
Fossil record
Genetic differences between species
Homeotic genes

50. Fruit fly embryo (10 hours)
homeotic genes control body development
Single mutation can result in major differences in body structure
Fly chromosomes
Mouse chromosomes
Fruit fly embryo (10 hours)
Mouse embryo (12 days)
Adult fruit fly
Adult mouse
Figure 11.14