The Macroevolutionary Puzzle

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The Macroevolutionary Puzzle

• Chapter 19

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Macroevolution

• The large-scale patterns, trends, and rates of
  change among families and other more inclusive
  groups of species

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19.1 Fossils

• Recognizable evidence of ancient life
• What do fossils tell us?
• Each species is a mosaic of ancestral and novel
  traits
• All species that ever evolved are related to one
  another by way of descent

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Stratification

• Fossils are found in sedimentary rock
• This type of rock is formed in layers
• In general, layers closest to the top were formed
  most recently

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Fossilization

• Organism becomes buried in ash or sediments
• Organic remains become infused with metal and
  mineral ions
• Carbon 14 dating

Figure 19.6Page 309
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19.2 Geologic Time Scale
Quaternary period
Cenozoic era
Phanerozoic eon
1
Tertiary period
65
Cretaceous period
Mesozoic era
138
Jurassic period
205
Triassic period

• Boundaries based on transitions in fossil record

210
Paleozoic era
Permian period
290
Carboniferous period
370
Devonian period
410
Silurian period
435
Ordovician period
505
Cambrian period
Cambrian period
570
Proterozoic eon
2,500 mya
Figure 19.4 (2)Page 308
Archean eon and earlier
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19.3 Continental Drift

• Idea that the continents were once joined and
  have since drifted apart
• Initially based on the shapes
• Wegener refined the hypothesis and named the
  theoretical supercontinent Pangea

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Changing Land Masses
10 mya
65 mya
260 mya
420 mya
Figure 19.8cPage 311
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Evidence of Movement

• Wegener cited evidence from glacial deposits and
  fossils
• Magnetic orientations in ancient rocks do not
  align with the magnetic poles
• Discovery of seafloor spreading provided a
  possible mechanism

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Plate Tectonics

• Earths crust is fractured into plates
• Movement of plates driven by upwelling of molten
  rock

Eurasian plate
North American plate
Pacific plate
Pacific plate
African plate
South American plate
Somali plate
Nazca plate
Indo-Australian plate
Antarctic plate
Figure 19.8bPage 311
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19.4 Comparative Morphology

• Comparing body forms and structures of major
  lineages
• Guiding principle
• When it comes to introducing change in
  morphology, evolution tends to follow the path of
  least resistance

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Morphological Divergence
1
early reptile
2
3
4
5
1
2
3
pterosaur

• Change from body form of a common ancestor
• Produces homologous structures

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1
chicken
2
3
1
2
bat
1
3
4
5
porpoise
2
4
5
3
penguin
2
3
1
2
human
3
4
Figure 19.10Page 312
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Morphological Convergence

• Individuals of different lineages evolve in
  similar ways under similar environmental
  pressures
• Produces analogous structures that serve similar
  functions

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19.5 Comparative Development

• Each animal or plant proceeds through a series of
  changes in form
• Similarities in these stages may be clues to
  evolutionary relationships
• Mutations that disrupt a key stage of development
  are selected against

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Altering Developmental Programs

• Some mutations shift a step in a way that natural
  selection favors
• Small changes at key steps may bring about major
  differences
• Insertion of transposons or gene mutations

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Development of Larkspurs

• Two closely related species have different petal
  morphology
• They attract different pollinators

front view
side view
D. decorum flower
front view
side view
D. nudicaule flower
Figure 19.12Page 314
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Development of Larkspurs

• Petal difference arises from a change in the rate
  of petal development

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D. decorum
4
Petal length (millimeters)
2
D. nudicaule
0
0
10
20
40
Days (after onset of meiosis)
Figure 19.12Page 314
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Similar Vertebrate Embryos

• Alterations that disrupted early development have
  been selected against

FISH
REPTILE
BIRD
MAMMAL
Figure 19.13aPage 315
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Similar Vertebrate Embryos
Aortic arches
Adult shark
Early human embryo
Two-chambered heart
Certain veins
Figure 19.13bPage 315
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Developmental Changes

• Changes in the onset, rate, or time of completion
  of development steps can cause allometric changes
• Adult forms that retain juvenile features

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Proportional Changes in Skull
Chimpanzee
Human
Figure 19.14bPage 315
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19.6 Comparative Biochemistry

• Kinds and numbers of biochemical traits that
  species share is a clue to how closely they are
  related
• Can compare DNA, RNA, or proteins
• More similarity means species are more closely
  related

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Comparing Proteins

• Compare amino acid sequence of proteins produced
  by the same gene
• Human cytochrome c (a protein)
• Identical amino acids in chimpanzee protein
• Chicken protein differs by 18 amino acids
• Yeast protein differs by 56

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Sequence Conservation

• Cytochrome c functions in electron transport
• Deficits in this vital protein would be lethal
• Long sequences are identical in wheat, yeast, and
  a primate

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Sequence Conservation
Yeast Wheat Primate
Figure 19.15Page 316-317
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Nucleic Acid Comparison

• Use single-stranded DNA or RNA
• Hybrid molecules are created, then heated
• The more heat required to break hybrid, the more
  closely related the species

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Molecular Clock

• Assumption Ticks (neutral mutations) occur at
  a constant rate
• Count the number of differences to estimate time
  of divergence

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19.7 Taxonomy

• Field of biology concerned with identifying,
  naming, and classifying species
• Somewhat subjective
• Information about species can be interpreted
  differently

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Binomial System

• Devised by Carl von Linne
• Each species has a two-part Latin name
• First part is generic
• Second part is specific name

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Higher Taxa

• Kingdom
• Phylum
• Class
• Order
• Family

• Inclusive groupings meant to reflect
  relationships among species

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Phylogeny

• The scientific study of evolutionary
  relationships among species
• Practical applications
• Allows predictions about the needs or weaknesses
  of one species on the basis of its known
  relationship to another

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Examples of Classification
corn
vanilla orchid
housefly
human
Plantae
Anthophyta
Monocotyledonae
Asparagales
Orchidaceae
Vanilla
V. planifolia
Figure 19.17Page 318
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A Cladogram
shark
mammal
crocodile
bird
feathers
fur
lungs
heart
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Five-Kingdom Scheme

• Proposed in 1969 by Robert Whittaker

Monera Protista Fungi Plantae Animalia
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Three-Domain Classification

• Favored by microbiologists

EUBACTERIA
ARCHAEBACTERIA
EUKARYOTES
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Six-Kingdom Scheme
EUBACTERIA
ARCHAEBACTERIA
PROTISTA
FUNGI
PLANTAE
ANIMALIA