Download - Evolution and systematics.ppt
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PowerPoint Lectures for Biology, Seventh Edition
Neil Campbell and Jane Reece
Lectures by Chris Romero
Descent with Modification: A Darwinian View of Life
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• The Origin of Species
– Focused biologists’ attention on the great diversity of organisms
Figure 22.1
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• Darwin made two major points in his book
– He presented evidence that the many species of organisms presently inhabiting the Earth are descendants of ancestral species
– He proposed a mechanism for the evolutionary process, natural selection
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• The historical context of Darwin’s life and ideas
Figure 22.2
Linnaeus (classification) Hutton (gradual geologic change)
Lamarck (species can change) Malthus (population limits)
Cuvier (fossils, extinction) Lyell (modern geology)
Darwin (evolution, nutural selection) Mendel (inheritance) Wallace (evolution, natural selection)
1750 American Revolution French Revolution U.S. Civil War
1800 1850 1900 1795 Hutton proposes his theory of gradualism.
1798 Malthus publishes “Essay on the Principle of Population.” 1809 Lamarck publishes his theory of evolution.
1830 Lyell publishes Principles of Geology. 1831–1836 Darwin travels around the world on HMS Beagle.
Darwin begins his notebooks on the origin of species. 1837 Darwin writes his essay on the origin of species. 1844
Wallace sends his theory to Darwin. 1858 The Origin of Species is published. 1859
Mendel publishes inheritance papers. 1865
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Resistance to the Idea of Evolution
• The Origin of Species
– Shook the deepest roots of Western culture
– Challenged a worldview that had been prevalent for centuries
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The Scale of Nature and Classification of Species
• The Greek philosopher Aristotle
– Viewed species as fixed and unchanging
• The Old Testament of the Bible
– Holds that species were individually designed by God and therefore perfect
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• Carolus Linnaeus
– Interpreted organismal adaptations as evidence that the Creator had designed each species for a specific purpose
– Was a founder of taxonomy, classifying life’s diversity “for the greater glory of God”
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Theories of Gradualism
• Gradualism
– Is the idea that profound change can take place through the cumulative effect of slow but continuous processes
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• Geologists Hutton and Lyell
– Perceived that changes in Earth’s surface can result from slow continuous actions still operating today
– Exerted a strong influence on Darwin’s thinking
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Lamarck’s Theory of Evolution
• Lamarck hypothesized that species evolve
– Through use and disuse and the inheritance of acquired traits
– But the mechanisms he proposed are unsupported by evidence
Figure 22.4
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• Darwin’s interest in the geographic distribution of species
– Was kindled by the Beagle’s stop at the Galápagos Islands near the equator west of South America
Figure 22.5
England EUROPE NORTH AMERICA
Galápagos Islands
Darwin in 1840, after his return
SOUTH AMERICA
Cape of Good Hope
Cape Horn
Tierra del Fuego
AFRICA HMS Beagle in port
AUSTRALIA
Tasmania New Zealand
PACIFIC OCEAN
And
es
ATLANTIC OCEAN
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The Origin of Species
• Darwin developed two main ideas
– Evolution explains life’s unity and diversity
– Natural selection is a cause of adaptive evolution
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Descent with Modification
• The phrase descent with modification
– Summarized Darwin’s perception of the unity of life
– States that all organisms are related through descent from an ancestor that lived in the remote past
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• In the Darwinian view, the history of life is like a tree
– With multiple branchings from a common trunk to the tips of the youngest twigs that represent the diversity of living organisms
Figure 22.7
Hyracoidea (Hyraxes)
Sirenia (Manatees
and relatives)
Year
s ag
o M
illio
ns o
f yea
rs a
go
Dei
noth
eriu
m
Mam
mut
Ste
godo
n
Mam
mut
hus
Pla
tybe
lodo
n
Bar
ythe
rium
Moe
rithe
rium
Elephas maximus
(Asia)
Loxodonta africana (Africa)
Loxodonta cyclotis (Africa)
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Natural Selection and Adaptation
• Evolutionary biologist Ernst Mayr
– Has dissected the logic of Darwin’s theory into three inferences based on five observations
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• Observation #1: For any species, population sizes would increase exponentially
– If all individuals that are born reproduced successfully
Figure 22.8
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• Observation #2: Nonetheless, populations tend to be stable in size
– Except for seasonal fluctuations
• Observation #3: Resources are limited
• Inference #1: Production of more individuals than the environment can support
– Leads to a struggle for existence among individuals of a population, with only a fraction of their offspring surviving
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• Observation #4: Members of a population vary extensively in their characteristics
– No two individuals are exactly alike
Figure 22.9
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• Observation #5: Much of this variation is heritable
• Inference #2: Survival depends in part on inherited traits
– Individuals whose inherited traits give them a high probability of surviving and reproducing are likely to leave more offspring than other individuals
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• Inference #3: This unequal ability of individuals to survive and reproduce
– Will lead to a gradual change in a population, with favorable characteristics accumulating over generations
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Artificial Selection
• In the process of artificial selection
– Humans have modified other species over many generations by selecting and breeding individuals that possess desired traits
Figure 22.10
Terminal bud
Lateral buds
Brussels sprouts Cabbage
Flower cluster
Leaves
Cauliflower
Flower and stems
Broccoli Wild mustard Kohlrabi
Stem
Kale
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Summary of Natural Selection
• Natural selection is differential success in reproduction
– That results from the interaction between individuals that vary in heritable traits and their environment
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• If an environment changes over time
– Natural selection may result in adaptation to these new conditions
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The Evolution of Drug-Resistant HIV
• In humans, the use of drugs
– Selects for pathogens that through chance mutations are resistant to the drugs’ effects
• Natural selection is a cause of adaptive evolution
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• Researchers have developed numerous drugs to combat HIV
– But using these medications selects for viruses resistant to the drugs
Figure 22.13
Patient No. 1
Patient No. 2
Patient No. 3
Per
cent
of H
IV re
sist
ant t
o 3T
C
Weeks
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Molecular Homologies
• Biologists also observe homologies among organisms at the molecular level
– Such as genes that are shared among organisms inherited from a common ancestor
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• Anatomical resemblances among species
– Are generally reflected in their molecules, their genes, and their gene products
Figure 22.16
Species
Human
Rhesus monkey
Mouse
Chicken
Frog
Lamprey 14%
54%
69%
87%
95%
100%
Percent of Amino Acids That Are Identical to the Amino Acids in a Human Hemoglobin Polypeptide
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• The Darwinian view of life
– Predicts that evolutionary transitions should leave signs in the fossil record
• Paleontologists
– Have discovered fossils of many such transitional forms
Figure 22.18
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What Is Theoretical about the Darwinian View of Life?
• In science, a theory
– Accounts for many observations and data and attempts to explain and integrate a great variety of phenomena
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• New information has revised our understanding of the tree of life
• Molecular Data
– Have provided new insights in recent decades regarding the deepest branches of the tree of life
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Previous Taxonomic Systems
• Early classification systems had two kingdoms
– Plants and animals
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• Robert Whittaker proposed a system with five kingdoms
– Monera, Protista, Plantae, Fungi, and Animalia
Figure 26.21
Plantae Fungi Animalia
Protista
Monera
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Reconstructing the Tree of Life: A Work in Progress
• A three domain system
– Has replaced the five kingdom system
– Includes the domains Archaea, Bacteria, and Eukarya
• Each domain
– Has been split by taxonomists into many kingdoms
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• One current view of biological diversity
Figure 26.22
Pro
teob
acte
ria
Chl
amyd
ias
Spi
roch
etes
Cya
noba
cter
ia
Gra
m-p
ositi
ve b
acte
ria
Kor
arch
aeot
es
Eur
yarc
haeo
tes,
cre
narc
haeo
tes,
nan
oarc
haeo
tes
Dip
lom
onad
s, p
arab
asal
ids
Eug
leno
zoan
s
Alv
eola
tes
(din
ofla
gella
tes,
api
com
plex
ans,
cili
ates
)
Stra
men
opile
s (w
ater
mol
ds, d
iato
ms,
gol
den
alga
e, b
row
n al
gae)
Cer
cozo
ans,
radi
olar
ians
Red
alg
ae
Chl
orop
hyte
s
Cha
roph
ycea
ns
Domain Archaea Domain Eukarya
Universal ancestor
Domain Bacteria
Chapter 27 Chapter 28
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Bry
ophy
tes
(mos
ses,
live
rwor
ts, h
ornw
orts
)
Plants
Fungi
Animals
See
dles
s va
scul
ar p
lant
s (fe
rns)
Gym
nosp
erm
s
Ang
iosp
erm
s
Am
oebo
zoan
s (a
moe
bas,
slim
e m
olds
)
Chy
trids
Zygo
te fu
ngi
Arb
uscu
lar m
ycor
rhiz
al fu
ngi
Sac
fung
i
Clu
b fu
ngi
Cho
anof
lage
llate
s
Spo
nges
Cni
daria
ns (j
ellie
s, c
oral
)
Bila
tera
lly s
ymm
etric
al a
nim
als
(ann
elid
s,
arth
ropo
ds, m
ollu
scs,
ech
inod
erm
s, v
erte
brat
es)
Chapter 29 Chapter 30 Chapter 28 Chapter 31 Chapter 32 Chapters 33, 34
Figure 26.21
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• Concept 25.2: Phylogenetic systematics connects classification with evolutionary history
• Taxonomy
– Is the ordered division of organisms into categories based on a set of characteristics used to assess similarities and differences
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Binomial Nomenclature
• Binomial nomenclature
– Is the two-part format of the scientific name of an organism
– Was developed by Carolus Linnaeus
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• The binomial name of an organism or scientific epithet
– Is latinized
– Is the genus and species
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Hierarchical Classification
• Linnaeus also introduced a system
– For grouping species in increasingly broad categories
Figure 25.8
Panthera pardus
Panthera
Felidae
Carnivora
Mammalia
Chordata
Animalia
Eukarya Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
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Linking Classification and Phylogeny
• Systematists depict evolutionary relationships
– In branching phylogenetic trees
Figure 25.9
Panthera pardus
(leopard)
Mephitis mephitis
(striped skunk)
Lutra lutra (European
otter)
Canis familiaris
(domestic dog)
Canis lupus (wolf)
Panthera Mephitis Lutra Canis
Felidae Mustelidae Canidae
Carnivora
Ord
er Fa
mily
G
enus
Sp
ecie
s
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• Each branch point
– Represents the divergence of two species
Leopard Domestic cat
Common ancestor
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• “Deeper” branch points
– Represent progressively greater amounts of divergence
Leopard Domestic cat
Common ancestor
Wolf
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• Concept 25.3: Phylogenetic systematics informs the construction of phylogenetic trees based on shared characteristics
• A cladogram
– Is a depiction of patterns of shared characteristics among taxa
• A clade within a cladogram
– Is defined as a group of species that includes an ancestral species and all its descendants
• Cladistics
– Is the study of resemblances among clades
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Cladistics
• Clades
– Can be nested within larger clades, but not all groupings or organisms qualify as clades
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• A valid clade is monophyletic
– Signifying that it consists of the ancestor species and all its descendants
Figure 25.10a
(a) Monophyletic. In this tree, grouping 1, consisting of the seven species B–H, is a monophyletic group, or clade. A mono- phyletic group is made up of an ancestral species (species B in this case) and all of its descendant species. Only monophyletic groups qualify as legitimate taxa derived from cladistics.
Grouping 1
D
C
E G
F
B
A
J
I
K H
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• A paraphyletic clade
– Is a grouping that consists of an ancestral species and some, but not all, of the descendants
Figure 25.10b
(b) Paraphyletic. Grouping 2 does not meet the cladistic criterion: It is paraphyletic, which means that it consists of an ancestor (A in this case) and some, but not all, of that ancestor’s descendants. (Grouping 2 includes the descendants I, J, and K, but excludes B–H, which also descended from A.)
D
C
E
B
G H
F
J
I
K
A
Grouping 2
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• A polyphyletic grouping
– Includes numerous types of organisms that lack a common ancestor
Figure 25.10c
(c) Polyphyletic. Grouping 3 also fails the cladistic test. It is polyphyletic, which means that it lacks the common ancestor of (A) the species in the group. Further- more, a valid taxon that includes the extant species G, H, J, and K would necessarily also contain D and E, which are also descended from A.
D
C
B
E G
F
H
A
J
I
K
Grouping 3
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Shared Primitive and Shared Derived Characteristics
• In cladistic analysis
– Clades are defined by their evolutionary novelties
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• A shared primitive character
– Is a homologous structure that predates the branching of a particular clade from other members of that clade
– Is shared beyond the taxon we are trying to define
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• A shared derived character
– Is an evolutionary novelty unique to a particular clade
Apomorphies for taxa B&C
A B C D E F
TIME
Cladogram or Phylogenetic Tree
TAXA
Apomorphy for taxon D
Apomorphy for taxa B-F
Similarity due to common ancestry- similar DNA sequences
Intraindividual homology? Similarity by common ancestry of features within
an individual, e.g., carpels and leaves (common ancestry by genes)
Similarity not by common ancestry.
Types? Convergence - independent evolution of a
similar feature in 2 or more lineages. Reversal - loss of a derived feature with re-
establishment of ancestral feature.
Convergence - Stem succulence and “spines” in Cactaceae and Euphorbia spp.