1. Evidence of Evolution Chapter 16
Biology Concepts and Applications, Eight Edition, by Starr, Evers, Starr. Brooks/Cole, Cengage Learning 2011.

2. 16.3 Evolution: Development of New Theories
Change that occurs in a line of descent (lineage)
19th-century naturalists tried to reconcile traditional beliefs with evidence of evolution
Georges Cuvier’s theory of catastrophism
Now abandoned hypothesis that catastrophic geologic forces unlike those of the present day shaped Earth’s surface
Lamarck’s theory of inheritance of acquired characteristics due to environmental factors
Species gradually improved over generations to drive to perfection. Ex. Giraffe  long neck

3. Voyage of the Beagle
Charles Darwin’s observations on a voyage around the world led to new ideas about species
Theory of uniformity (gradual, repetitive change)
Idea that gradual repetitive
processes occurring over
long time spans shaped
Earth’s surface
Theory challenged idea that
Earth was 6,000 yrs old
**However, must have taken
longer to sculpt Earth’s surface

4. Voyage of the Beagle

5. 16.4 Descent with Modification
Darwin compared the modern armadillo with the extinct glyptodont
Glyptodont – Argentina
Extinct but similar to Armadillo
Armadillo – live only in
Places the Glyptodont once lived

6. People who influenced Darwin
Henslow – Botanist, friend and mentor. Introduced him to Capt. Fitzroy
Malthus – Economist, Theory that overpopulation will drive humans extinct
Lyell – Geologist, Theory that the earth was older than thought at that time. Found old rocks and fossils
Emma – His wife, supporter and proofreader of all his manuscripts

7. Variations in Traits
Darwin observed that variations in traits influence an individual’s ability to secure resources – to survive and reproduce

8. A Key Insight – Variation in Traits
Adaptation (adaptive trait)
A heritable trait the enhances an individual’s fitness
Artificial selection
Selective breeding of animals by humans

9. Darwin, Wallace, and Natural Selection
In 1858, Charles Darwin and Alfred Wallace independently proposed a new theory, that natural selection can bring about evolution

10. Key Concepts: A THEORY TAKES FORM
Evidence of evolution, or changes in lines of descent, gradually accumulated
Charles Darwin and Alfred Wallace independently developed a theory of natural selection to explain how heritable traits that define each species evolve

11. Theory of Natural Selection
Process in which environmental pressures result in the differential survival and reproduction of individuals of a population who vary in the details of shared, heritable traits
Can lead to increased fitness
Fitness
Degree of adaptation to an environment, as measured by an individual’s relative genetic contribution to future generations.

12. Main Premises of the Theory of Natural Selection
1. A population tends to grow until it begins to exhaust the resources of its environment
2. Individuals must then compete for resources such as food and shelter from predators
3. Individuals with forms of traits that make them more competitive tend to produce more offspring

13. Inferences of the Theory of Natural Selection
Environmental factors acting on a range of traits in a population influence differential survival and reproduction of individuals (natural selection)
Forms of heritable traits that impart greater fitness to an individual become more common in a population over generations

14. Comparative Morphological Evidence

15. Fossil Evidence Fossil  physical evidence Of an organism that lived
In the ancient past
Mapping rock formation:
Deeper layers hold
Fossils of simple marine
Life. Layers above held
Similar but more intricate
Fossils. Higher layers,
Similar that belong to
Modern species.

16. 16.5 Fossil Evidence Fossils
Physical evidence of life in the distant past
Found in stacked layers of sedimentary rock
Younger fossils in more recently deposited layers
Older fossils underneath, in older layers

17. Fossilization

18. Fossilization
Begins when organisms become covered by sediments or volcanic ash.
Water seeps into the remains, and metal ions and other organic compounds dissolved in water replace the minerals in the bones and hard tissues.
Pressure and mineralization process transforms the remains into rock

19. Stratification
Layers of sedimentary rock made from river silt, sand, volcanic ash, and other materials from land to sea

20. Interpreting the Fossil Record
The fossil record is incomplete
Have fossils for 250,000 known species
Most times, remains are obliterated by decay because organic materials decompose in the presence of oxygen
Material remains IF encased in air-excluding materials (sap, tar, ice, or mud)
Favors species with hard parts, dense populations with wide distribution, and that persisted a long time

21. Dating Fossils Geologic time scale  Chronology of Earth’s History
Boundaries for major intervals determined by transitions in the fossil record
Correlated with macroevolutionary events
Includes dates obtained by radiometric dating

22. Macroevolution
Major patterns, trends, and rates of change among lineages (Geologic time scale)

23. Radiometric Dating: Half-Life
Radioactive dating
Method of estimating the age of a rock or fossil by measuring the content and proportions of a radioisotope and its daughter elements
Oldest terrestrial rock (tiny zircon crystal) in Australia
4.404 billion years old
Recent fossils that still contain carbon can by dated by measuring their carbon 14 content
Complete decay of 14C occurs in 60,000 years

24. Parent isotope remaining (%)
parent isotope in
newly formed rock
100 75
after one half-life
Parent isotope remaining (%) 50
after two half-lives 25 1 2 3 4
Time (half-life) for any radioisotope
a A simple way to think about the decay of a radioisotope to a more
stable isotope, as plotted against time.
Fig a, p.248

25. Fig b-d, p.248

26. Key Concepts: EVIDENCE FROM BIOGEOGRAPHY
Correlating evolutionary theories with geologic history helps explain the distribution of species, past and present

27. Biogeography – evidence for evolution
Alfred Wallace  Biogeography
Study of patterns in the geographic distribution of species and communities
Looked at the natural forces that shape life
Raised ?
Isolated species look suspiciously similar to species living across vast expansions of open ocean, or on the other side of mountain ranges

28. Biogeography – evidence for evolution
Rhea
South America
Ostrich
Africa
All flightless birds.
Long, muscular legs.
Inhabit flat, open grasslands
about the same distance from
the equator.*Common Ancestors!
Emu
Australia

29. 16.7 Plate Tectonics Theory
Movements of Earth’s tectonic plates rafted land masses to new positions
Pangea: First ancient supercontinent that formed about 237 million years ago and broke up about 152 million years ago
Gondwana  supercontinent that existed before Pangae, more than 500 million years ago
Include Southern Hemisphere and India and Arabia
Most modern species live only in places that were once part of Gondwana

30. 16.7 Plate Tectonics Theory
Plate Tectonics OR Continental drift
Theory that Earth’s outer layer of rock is cracked into plates
Slow movement of which rafts continents to new locations over geologic time
Movements had profound impacts on the directions of life’s evolution
Evidence of at least 5x since Earth’s outer layer solidified 4.55 billion years ago, a single supercontinent with one ocean lapping the coast line formed and then split up.
14 million years ago, that Earth and it’s continents mirror today

31. Evidence of Drifting Continents
Evidence for plate tectonics theory
Distribution of global land masses
Global fossil distribution
Magnetic rocks
Seafloor spreading from mid-oceanic ridges
In faults (fault lines)
Volcanic island chains  form as a plate moves across an undersea hot spot (place where a narrow plume of molten rock wells up from deep inside Earth and ruptures a plate

32. Drifting Continents

33. a 420 mya
b 237 mya
c 152 mya
d 66 mya
e 14 mya
Fig , p.251

34. Key Concepts: EVIDENCE FROM COMPARATIVE MORPHOLOGY
Species of different lineages often have similar body parts that may be evidence of descent from a shared ancestor

35. Comparative Morphological Evidence
Comparative Morphology
Study of body parts and structures among groups of organisms
Organisms outwardly similar but different internally
Fish and porpoises  Very different
Outwardly different but similar internally
Human arm and porpoise flipper
Elephant leg and bat wing
Useless parts 
leg bones in snakes or vestiges of tail in humans

36. 16.8 Comparative Morphology
Comparisons of body form and structure of major groups of organisms
Reveals evolutionary connections among lineages

37. Morphological Divergence
Homologous structures:
Similar body parts that became modified differently in different lineages
Evidence of descent from a common ancestor
Morphological divergence
Evolutionary pattern in which a body part of an ancestor changes in its descendants

38. Homologous Structures
Morphological
Divergence

39. 1 2 3 4
stem reptile 5
Fig a, p.252

40. 1 2 3
pterosaur 4
Fig b, p.252

41. 1 2
chicken 3
Fig c, p.252

42. 2 3
penguin
Fig d, p.252

43. 1
porpoise 4 2 5 3
Fig e, p.252

44. 1 2
bat 3 4 5
Fig f, p.252

45. 1 2 3 4 5
human
Fig g, p.252

46. 1 2 3 4
elephant 5
Fig h, p.252

47. Morphological Convergence
Analogous structures:
Body parts in different lineages that look alike, but evolved separately after the lineages diverged
Did not evolve in a common ancestor
Morphological convergence
Evolutionary pattern in which similar body parts evolve separately in different lineages

48. Analogous Structures

49. Morphological convergence
Insects
Bats
Humans
Crocodiles
Birds
wings
wings
wings
limbs with
5 digits
Fig d, p.253

50. 16.9 Changes in Patterns of Development
Similarities in patterns of embryonic development suggest shared ancestry
Mutations in genes that affect development may cause morphological shifts in a lineage
Gene duplications account for some differences between closely related lineages

51. Comparative Embryology: Vertebrate Relationships
Human
Mouse
Bat
Chicken
Alligator
All vertebrate embryos have similar stages:
- Stage with 4 limb buds, a tail, and divisions called somites
along their back

52. Key Concepts: EVIDENCE FROM COMPARATIVE BIOCHEMISTRY
Molecular comparisons help us discover and confirm relationships among species and lineages

53. DNA, RNA, and Proteins
Comparisons of DNA, RNA, and proteins reveal and clarify evolutionary relationships