This document discusses macroevolution and the diversity of life. It covers topics such as speciation, the origin of species, mechanisms of speciation like allopatric speciation, mass extinctions, classifying diversity through taxonomy and phylogenetic trees, and how plate tectonics and extinction events have driven macroevolution. Key events mentioned include the Permian and Cretaceous extinctions that opened opportunities for new species to emerge, like mammals increasing after the demise of dinosaurs.

1. © 2010 Pearson Education, Inc.
MACROEVOLUTION AND THE DIVERSITY
OF LIFE
• Macroevolution:
– Encompasses the major biological changes evident in the fossil record
– Includes the formation of new species

2. © 2010 Pearson Education, Inc.
• Speciation:
– Is the focal point of macroevolution
– May occur based on two contrasting patterns

3. © 2010 Pearson Education, Inc.
• In nonbranching evolution:
– A population transforms but
– Does not create a new species
Video: Galápagos Islands Overview

4. © 2010 Pearson Education, Inc.
• In branching evolution, one or more new species branch from a
parent species that may:
– Continue to exist in much the same form or
– Change considerably

5. Branching Evolution
(results in speciation)
Nonbranching Evolution
(no new species)
PATTERNS OF EVOLUTION
Figure 14.1

6. © 2010 Pearson Education, Inc.
THE ORIGIN OF SPECIES
• Species is a Latin word meaning:
– “Kind” or
– “Appearance.”

7. © 2010 Pearson Education, Inc.
What Is a Species?
• The biological species concept defines a species as
– “A group of populations whose members have the potential to interbreed
and produce fertile offspring”

8. Similarity between different species
Figure 14.2a

9. Diversity within one species
Figure 14.2b

10. © 2010 Pearson Education, Inc.
Reproductive Barriers between Species
• Prezygotic barriers prevent mating or fertilization between
species.
Video: Blue-footed Boobies Courtship Ritual
Video: Albatross Courtship Ritual
Video: Giraffe Courtship Ritual

11. VIABLE, FERTILE
OFFSPRING
Hybrid breakdown
FERTILIZATION
(ZYGOTE FORMS)
INDIVIDUALS OF
DIFFERENT SPECIES
MATING ATTEMPT
Reduced hybrid fertility
Reduced hybrid viability
Temporal isolation
Habitat isolation
Behavioral isolation
Mechanical isolation
Gametic isolation
Prezygotic Barriers
Postzygotic Barriers
Figure 14.3

12. © 2010 Pearson Education, Inc.
• Prezygotic barriers include:
– Temporal isolation
– Habitat isolation
– Behavioral isolation
– Mechanical isolation
– Gametic isolation

13. Temporal Isolation
Skunk species that mate at different times
Figure 14.4a

14. Habitat Isolation
Garter snake species from different habitats
Figure 14.4b

15. Mating ritual of blue-footed boobies
Behavioral Isolation
Figure 14.4c

16. Mechanical Isolation
Snail species whose genital openings cannot align
Figure 14.4d

17. Sea urchin species whose gametes cannot fuse
Gametic Isolation
Figure 14.4e

18. © 2010 Pearson Education, Inc.
• Postzygotic barriers operate if:
– Interspecies mating occurs and
– Hybrid zygotes form

19. © 2010 Pearson Education, Inc.
VIABLE, FERTILE
OFFSPRING
Hybrid breakdown
FERTILIZATION
(ZYGOTE FORMS)
INDIVIDUALS OF
DIFFERENT SPECIES
MATING ATTEMPT
Reduced hybrid fertility
Reduced hybrid viability
Temporal isolation
Habitat isolation
Behavioral isolation
Mechanical isolation
Gametic isolation
Prezygotic Barriers
Postzygotic Barriers
Figure 14.3

20. © 2010 Pearson Education, Inc.
• Postzygotic barriers include:
– Reduced hybrid viability
– Reduced hybrid fertility
– Hybrid breakdown

21. Frail hybrid salamander offspring
Reduced Hybrid Viability
Figure 14.5a

22. Reduced Hybrid Fertility
Mule (sterile hybrid of
horse and donkey)
Donkey
Mule
Horse
Figure 14.5b

23. Hybrid Breakdown
Sterile next-generation rice hybrid
Figure 14.5c

24. © 2010 Pearson Education, Inc.
Mechanisms of Speciation
• A key event in the potential origin of a species occurs when a
population is severed from other populations of the parent
species.

25. © 2010 Pearson Education, Inc.
• Species can form by:
– Allopatric speciation, due to geographic isolation

26. © 2010 Pearson Education, Inc.
Video: Grand Canyon
Allopatric Speciation
• Geologic processes can:
– Fragment a population into two or more isolated populations
– Contribute to allopatric speciation
Video: Volcanic Eruption
Video: Lava Flow

27. Ammospermophilus harrisii Ammospermophilus leucurus
Figure 14.7

28. © 2010 Pearson Education, Inc.
• Speciation occurs only with the evolution of reproductive barriers
between the isolated population and its parent population.

29. © 2010 Pearson Education, Inc.
What Is the Tempo of Speciation?
• There are two contrasting models of the pace of evolution:
– The gradual model, in which big changes (speciations) occur by the
steady accumulation of many small changes
– The punctuated equilibria model, in which there are
– Long periods of little change, equilibrium, punctuated by
– Abrupt episodes of speciation

30. Punctuated
model
Graduated
model
Time
Figure 14.10

31. © 2010 Pearson Education, Inc.
EARTH HISTORY AND MACROEVOLUTION
• Macroevolution is closely tied to the history of the Earth.

32. © 2010 Pearson Education, Inc.
Geologic Time and the Fossil Record
• The fossil record is:
– The sequence in which fossils appear in rock strata
– An archive of macroevolution

33. Figure 14.14a

34. Figure 14.14b

35. Figure 14.14c

36. Figure 14.14d

37. © 2010 Pearson Education, Inc.
• Geologists have established a geologic time scale reflecting a
consistent sequence of geologic periods.
Animation: Macroevolution
Animation: The Geologic Record

38. Table 14.1

39. © 2010 Pearson Education, Inc.
• Fossils are reliable chronological records only if we can
determine their ages, using:
– The relative age of fossils, revealing the sequence in which groups of
species evolved, or
– The absolute age of fossils, requiring other methods such as radiometric
dating

40. © 2010 Pearson Education, Inc.
• Radiometric dating:
– Is the most common method for dating fossils
– Is based on the decay of radioactive isotopes
– Helped establish the geologic time scale

41. Carbon-14 in shell
Time (thousands of years)
Radioactive decay
of carbon-14
How
carbon-14
dating is
used to
determine
the vintage
of a
fossilized
clam shell
Carbon-14radioactivity
(as%oflivingorganism’s
C-14toC-12ratio)
100
75
0
50
25
0 5.6 50.411.2 16.8 22.4 28.0 33.6 39.2 44.8
Figure 14.15

42. © 2010 Pearson Education, Inc.
Plate Tectonics and Macroevolution
• The continents are not locked in place. Continents drift about the
Earth’s surface on plates of crust floating on a flexible layer
called the mantle.
• The San Andreas fault is:
– In California
– At a border where two plates slide past each other

43. Figure 14.16

44. © 2010 Pearson Education, Inc.
• About 250 million years ago:
– Plate movements formed the supercontinent Pangaea
– The total amount of shoreline was reduced
– Sea levels dropped
– The dry continental interior increased in size
– Many extinctions occurred

45. Pangaea
Present
PaleozoicCenozoicMesozoic
251millionyearsago13565
Laurasia
Gondwana
Eurasia
India
Madagascar
North America
Africa
South
America
Antarctica Australia
Figure 14.17

46. © 2010 Pearson Education, Inc.
• About 180 million years ago:
– Pangaea began to break up
– Large continents drifted increasingly apart
– Climates changed
– The organisms of the different biogeographic realms diverged

47. © 2010 Pearson Education, Inc.
• Plate tectonics explains:
– Why Mesozoic reptiles in Ghana (West Africa) and Brazil look so similar
– How marsupials were free to evolve in isolation in Australia

48. Mass Extinctions and Explosive Diversifications
of Life
• The fossil record reveals that five mass extinctions have occurred
over the last 600 million years.
• The Permian mass extinction:
– Occurred at about 250 million years ago
– Claimed about 96% of marine species
© 2010 Pearson Education, Inc.

49. © 2010 Pearson Education, Inc.
• The Cretaceous extinction:
– Occurred at the end of the Cretaceous period, about 65 million years ago
– Included the extinction of all the dinosaurs except birds
– Permitted the rise of mammals

50. © 2010 Pearson Education, Inc.
CLASSIFYING THE DIVERSITY OF LIFE
• Systematics focuses on:
– Classifying organisms
– Determining their evolutionary relationships
• Taxonomy is the:
– Identification of species
– Naming of species
– Classification of species

51. © 2010 Pearson Education, Inc.
Some Basics of Taxonomy
• Scientific names ease communication by:
– Unambiguously identifying organisms
– Making it easier to recognize the discovery of a new species
• Carolus Linnaeus (1707–1778) proposed the current taxonomic
system based upon:
– A two-part name for each species
– A hierarchical classification of species into broader groups of organisms

52. © 2010 Pearson Education, Inc.
Naming Species
• Each species is assigned a two-part name or binomial, consisting
of:
– The genus
– A name unique for each species
• The scientific name for humans is Homo sapiens, a two part
name, italicized and latinized, and with the first letter of the
genus capitalized.

53. © 2010 Pearson Education, Inc.
Hierarchical Classification
• Species that are closely related are placed into the same genus.

54. Leopard (Panthera pardus)
Figure 14.19a

55. Tiger (Panthera tigris)
Figure 14.19b

56. Lion (Panthera leo)
Figure 14.19c

57. Jaguar (Panthera onca)
Figure 14.19d

58. © 2010 Pearson Education, Inc.
• The taxonomic hierarchy extends to progressively broader
categories of classification, from genus to:
– Family
– Order
– Class
– Phylum
– Kingdom
– Domain

59. Leopard
(Panthera pardus)
Species
Panthera
pardus
Genus
Panthera
Family
Felidae
Order
Carnivora
Class
Mammalia
Phylum
Chordata
Kingdom
Animalia
Domain
Eukarya
Figure 14.20

60. © 2010 Pearson Education, Inc.
Classification and Phylogeny
• The goal of systematics is to reflect evolutionary relationships.
• Biologists use phylogenetic trees to:
– Depict hypotheses about the evolutionary history of species
– Reflect the hierarchical classification of groups nested within more
inclusive groups

61. Panthera
pardus
(leopard)
SpeciesGenus
Felidae
Order
Carnivora
Family
Canis
Lutra
Panthera
Mephitis
Canidae
Mustelidae
Canis
lupus
(wolf)
Canis
latrans
(coyote)
Lutra
lutra
(European
otter)
Mephitis
mephitis
(striped skunk)
Figure 14.21

62. © 2010 Pearson Education, Inc.
Cladistics
• Cladistics is the scientific search for clades.
• A clade:
– Consists of an ancestral species and all its descendants
– Forms a distinct branch in the tree of life

63. Hair, mammary
glands
Long gestation
Gestation
Duck-billed
platypus
Iguana
Outgroup
(reptile)
Ingroup
(mammals)
Beaver
Kangaroo
Figure 14.23

64. © 2010 Pearson Education, Inc.
Classification: A Work in Progress
• Linnaeus:
– Divided all known forms of life between the plant and animal kingdoms
– Prevailed with his two-kingdom system for over 200 years
• In the mid-1900s, the two-kingdom system was replaced by a
five-kingdom system that:
– Placed all prokaryotes in one kingdom
– Divided the eukaryotes among four other kingdoms

65. © 2010 Pearson Education, Inc.
• In the late 20th century, molecular studies and cladistics led to the
development of a three-domain system, recognizing:
– Two domains of prokaryotes (Bacteria and Archaea)
– One domain of eukaryotes (Eukarya)
Animation: Classification Schemes

66. Kingdom
Animalia
Domain ArchaeaEarliest
organisms
Domain Bacteria
Domain Eukarya
Kingdom
Fungi
Kingdom
Plantae
The protists
(multiple
kingdoms)
Figure 14.25

67. Evolution Connection:
Rise of the Mammals
• Mass extinctions:
– Have repeatedly occurred throughout Earth’s history
– Were followed by a period of great evolutionary change
© 2010 Pearson Education, Inc.

68. © 2010 Pearson Education, Inc.
• Fossil evidence indicates that:
– Mammals first appeared about 180 million years ago
– The number of mammalian species
– Remained steady and low in number until about 65 million years
ago and then
– Greatly increased after most of the dinosaurs became extinct

69. American black bear
Eutherians
(5,010 species)
Millions of years ago
Monotremes
(5 species)
Marsupials
(324 species)
Ancestral
mammal
Reptilian
ancestor
Extinction of
dinosaurs
250 200 150 100 5065 0
Figure 14.26