Transcript Species

Chapter 14
How Biological Diversity Evolves
PowerPoint® Lectures for
Campbell Essential Biology, Fourth Edition
– Eric Simon, Jane Reece, and Jean Dickey
Campbell Essential Biology with Physiology, Third Edition
– Eric Simon, Jane Reece, and Jean Dickey
Lectures by Chris C. Romero, updated by Edward J. Zalisko
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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”
• Species is a Latin word meaning:
– “Kind” or
– “Appearance.”
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PATTERNS OF EVOLUTION
Nonbranching Evolution
(no new species)
Branching Evolution
(results in speciation)
Figure 14.1
Similarity between different species
Diversity within one species
Figure 14.2
Reproductive Barriers between Species
Prezygotic barriers prevent
mating or fertilization between
species.
Zygote
Gametes Prezygotic barriers
• Temporal isolation
• Habitat isolation
• Behavioral isolation
• Mechanical isolation
• Gametic isolation
Viable,
Postzygotic barriers
fertile
• Reduced hybrid viability offspring
• Reduced hybrid fertility
• Hybrid breakdown
Figure 14.UN1
Temporal Isolation
Skunk species that mate at different times
Figure 14.4a
Habitat Isolation
Garter snake species from different habitats
Figure 14.4b
Behavioral Isolation
Mating ritual of blue-footed boobies
Figure 14.4c
Mechanical Isolation
Snail species whose genital openings cannot align
Figure 14.4d
Gametic Isolation
Sea urchin species whose gametes cannot fuse
Figure 14.4e
POSTZYGOTIC BARRIERS
Reduced Hybrid Viability Reduced Hybrid Fertility
Hybrid Breakdown
Horse
Donkey
Mule
Figure 14.5
• Speciation or a new Species can form by:
– Allopatric speciation, due to geographic isolation
– Sympatric speciation, without geographic isolation
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Ammospermophilus harrisii
Ammospermophilus leucurus
Figure 14.7
Sympatric Speciation
• Sympatric speciation occurs:
– While the new species and old species live in the same time and place
– If a genetic change produces a reproductive barrier between the new and
old species
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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
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Punctuated
model
Time
Graduated
model
Figure 14.10
Wing claw
(like reptile)
Teeth
(like reptile)
Feathers
Long tail with
many vertebrae
(like reptile)
Fossil
Artist’s reconstruction
Figure 14.11
• Bird wings are modified forelimbs that were previously adapted
for non-flight functions, such as:
– Thermal regulation
– Courtship displays
– Camouflage
• The first flights may have been only glides or extended hops as
the animal pursued prey or fled from a predator.
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Chimpanzee fetus
Chimpanzee adult
Human fetus
Human adult
(paedomorphic features)
Figure 14.13
Figure 14.14
• Geologists have established a geologic time scale reflecting a
consistent sequence of geologic periods.
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Domain Bacteria
Earliest
organisms
Domain Archaea
The protists
(multiple
kingdoms)
Kingdom
Plantae
Domain Eukarya
The three-domain
classification system
Kingdom
Fungi
Kingdom
Animalia
Figure 14.25
Ancestral
mammal
Monotremes
(5 species)
Extinction of
dinosaurs
Reptilian
ancestor
Marsupials
(324 species)
Eutherians
(5,010 species)
250
65 50
Millions of years ago
200
150
100
0
Figure 14.26a
Table 14.1
Mass Extinctions
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Evolution Connection:
Rise of the Mammals
• Mass extinctions:
– H
ave repeatedly occurred throughout Earth’s history
– Were followed by a period of great evolutionary change
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• 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
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Hierarchical Classification
Taxa
Binomial species name:
Dendroica fusca
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Difference between homologous and
derived traits
Homologous bones in forelimbs
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Wings are derived traits
An example of convergent
evolution
Convergent Evolution
of Wings
Insects
Birds
Pterosaurs
Bats
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• 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
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• Radiometric dating:
– Is the most common method for dating fossils
– Is based on the decay of radioactive isotopes
– H
elped establish the geologic time scale
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Carbon-14 radioactivity
(as % of living organism’s
C-14 to C-12 ratio)
Radioactive decay
of carbon-14
100
75
50
25
0
0
5.6 11.2 16.8 22.4 28.0 33.6 39.2 44.8 50.4
Time (thousands of years)
How
carbon-14
dating is
used to
determine
the vintage
of a
fossilized
clam shell
Carbon-14 in shell
Figure 14.15
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
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Figure 14.16
The Process of Science:
Did a Meteor Kill the Dinosaurs?
• Observation
: A b o u t
6 5
m i l l i o n
th a t:
– Dinosaurs (except birds) became extinct
– A thin layer of clay rich in iridium was deposited
–
The climate
– cooled
M a n y p l a n t sp e c ie s d ie d o u t
– Seas were receding
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y e a r s
a g o ,
th e
f o ssi l
• Question: Is the iridium layer the result of fallout from a huge
cloud of dust that billowed into the atmosphere when a large
meteor or asteroid hit Earth?
• Hypothesis: The mass extinction 65 million years ago was caused
by the impact of an extraterrestrial object.
• Prediction: A huge impact crater of the right age should be found
somewhere on Earth’s surface.
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• Results: Near the Yucatán Peninsula, a huge impact crater was
found that:
– Dated from the predicted time
– Was about the right size
– Was capable of creating a cloud that could have blocked enough sunlight
to change the Earth’s climate for months
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Chicxulub
crater
Figure 14.18-3
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
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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
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Naming Species
•
Each species is assigned a two
of:
•
–
The
–
A name unique for each species
genus
The scientific name for humans is
name, italicized and latinized, and with the first letter of the
- pa
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
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Panthera pardus
Leopard (Panthera pardus)
Panthera tigris
Panthera leo
Tiger (Panthera
tigris)
Lion (Panthera leo)
Panthera onca
Jaguar (Panthera onca)
Figure 14.19
• The taxonomic hierarchy extends to progressively broader
categories of classification, from genus to:
– Family
– Order
– Class
– Phylum
– Kingdom
– Domain
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Species
Panthera
pardus
Genus
Panthera
Leopard
(Panthera pardus)
Family
Felidae
Order
Carnivora
Class
Mammalia
Phylum
Chordata
Kingdom
Animalia
Domain
Eukarya
Figure 14.20
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
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Order
Family
Genus
Species
Felidae
Panthera
Panthera
pardus
(leopard)
Mephitis
Mephitis
mephitis
(striped skunk)
Carnivora
Mustelidae
Lutra
Lutra
lutra
(European
otter)
Canis
latrans
(coyote)
Canidae
Canis
Canis
lupus
(wolf)
Figure 14.21
The Cladistic Revolution
• 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
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Cladogram
Iguana
Outgroup
(reptile)
Duck-billed
platypus
Hair, mammary
glands
Gestation
Kangaroo
Ingroup
(mammals)
Beaver
Long gestation
Figure 14.23
Lizards
and snakes
Crocodilians
Pterosaurs
Common
ancestor of
crocodilians,
dinosaurs,
and birds
Cladogram
Ornithischian
dinosaurs
Saurischian
dinosaurs
Birds
Figure 14.24
• 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)
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