Transcript You Light Up My Life - The Westminster Schools

The Macroevolutionary Puzzle
Chapter 19
Macroevolution
The large-scale patterns, trends,
and rates of change among
families and other more inclusive
groups of species
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
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
Fossilization
• Organism becomes
buried in ash or
sediments
• Organic remains
become infused with
metal and mineral ions
• Carbon 14 dating
Figure 19.6
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19.2
Phanerozoic
eon
Geologic
Time
Scale
• Boundaries
based on
transitions
in fossil
record
Cenozoic
era
Mesozoic
era
Quaternary period
1
Tertiary period
65
Cretaceous period
138
Jurassic period
Triassic period
Paleozoic
era
205
210
Permian period
290
Carboniferous period
370
Devonian period
Silurian period
Ordovician period
Cambrian
Cambrianperiod
period
410
435
505
570
Proterozoic eon
Figure 19.4 (2)
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Archean eon and earlier
2,500
mya
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
Changing Land Masses
420 mya
260 mya
65 mya
10 mya
Figure 19.8c
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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
Plate Tectonics
• Earth’s crust
is fractured
into plates
• Movement of
plates driven
by upwelling
of molten
rock
Eurasian
plate
North
Pacific
plate
American
plate
Pacific
plate
African
plate
Nazca
plate
South
American
plate
Somali
plate
IndoAustralian
plate
Antarctic plate
Figure 19.8b
Page 311
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
Morphological
Divergence
4
5
21
3
• Change from
body form of a
common
ancestor
• Produces
homologous
structures
4
pterosaur
1
chicken
2
3
1
2
bat
3 4
1
5
porpoise
2
4
3
5
penguin
2
1
Figure 19.10
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3
early
reptile
21
2
3
4
5
3
human
Morphological Convergence
• Individuals of different
lineages evolve in similar
ways under similar
environmental pressures
• Produces analogous
structures that serve similar
functions
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
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
Development of Larkspurs
• Two closely related
species have
different petal
morphology
• They attract
different pollinators
side view
front view
D. decorum flower
side view
front view
D. nudicaule flower
Figure 19.12
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Development of Larkspurs
Petal length (millimeters)
• Petal difference arises from a change in
the rate of petal development
6
D. decorum
4
2
D. nudicaule
0
0
10
20
40
Days (after onset of meiosis)
Figure 19.12
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Similar Vertebrate Embryos
• Alterations that disrupted early development
have been selected against
FISH
REPTILE
BIRD
MAMMAL
Figure 19.13a
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Similar Vertebrate Embryos
Adult
shark
Aortic arches
Two-chambered
heart
Certain veins
Early
human
embryo
Figure 19.13b
Page 315
Developmental Changes
• Changes in the onset, rate, or time of
completion of development steps can
cause allometric changes
• Adult forms that retain juvenile
features
Proportional Changes in Skull
Chimpanzee
Human
Figure 19.14b
Page 315
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
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
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
Sequence Conservation
Yeast
Wheat
Primate
Figure 19.15
Page 316-317
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
Molecular Clock
• Assumption: “Ticks” (neutral
mutations) occur at a constant
rate
• Count the number of differences
to estimate time of divergence
19.7 Taxonomy
• Field of biology concerned with
identifying, naming, and classifying
species
• Somewhat subjective
• Information about species can be
interpreted differently
Binomial System
• Devised by Carl von Linne
• Each species has a two-part
Latin name
• First part is generic
• Second part is specific name
Higher Taxa
•
•
•
•
•
Kingdom
Phylum
Class
Order
Family
• Inclusive groupings
meant to reflect
relationships among
species
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
Examples of Classification
corn
Kingdom
Phylum
Class
Order
Family
Genus
Species
Plantae
Anthophyta
Monocotyledonae
Poales
Poaceae
Zea
Z. mays
vanilla orchid
Plantae
Anthophyta
Monocotyledonae
Asparagales
Orchidaceae
Vanilla
V. planifolia
housefly
Animalia
Anthropoda
Insecta
Diptera
Muscidae
Musca
M. domestica
human
Animalia
Chordata
Mammalia
Primates
Hominidae
Homo
H. sapiens
Figure 19.17
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A Cladogram
shark
mammal
crocodile
fur
lungs
heart
bird
feathers
Five-Kingdom Scheme
• Proposed in
1969 by Robert
Whittaker
Monera
Protista
Fungi
Plantae
Animalia
Three-Domain Classification
• Favored by microbiologists
EUBACTERIA
ARCHAEBACTERIA
EUKARYOTES
Six-Kingdom Scheme
EUBACTERIA
ARCHAEBACTERIA
PROTISTA
FUNGI
PLANTAE
ANIMALIA