Chapter 14 Speciation and Extinction Island: Morandi
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reserved. No reproduction or distribution without the prior written
consent of McGraw-Hill Education.
Slide 2
What Is a Species? Section 14.1Figure 14.1 Countless small
evolutionary changes have accumulated through the last 3.8 billion
years, leading to todays great diversity of life. Bacteria: S.
Lowry/University Ulster/Getty Images; Tree: Corbis RF; Bird: IT
Stock/PunchStock RF How do small mutations, even if numerous,
produce new species? First, we must explore what defines a
species.
Slide 3
What Is a Species? Section 14.1Figure 14.3 In the 1700s,
Carolus Linnaeus defined species by appearance. He also created a
naming scheme for species. Butterfly collection: IT Stock
Free/Alamy RF Each species name combines the broader classification
genus with the term species. The scientific name for humans, for
example, is Homo sapiens. More recently, the biological species
concept defines species based on their potential to interbreed and
produce fertile offspring.
Slide 4
What Is a Species? Section 14.1 Speciation, the formation of
new species, occurs when some individuals can no longer interbreed
with the rest of the group. Figure 14.3 Butterfly collection: IT
Stock Free/Alamy RF
Slide 5
Clicker Question #1 The biological species concept cannot be
applied to A. humans. B. plants. C. extinct organisms. D. organisms
that look alike. Flower: Doug Sherman/Geofile/RF
Slide 6
Clicker Question #1 The biological species concept cannot be
applied to A. humans. B. plants. C. extinct organisms. D. organisms
that look alike. Flower: Doug Sherman/Geofile/RF
Slide 7
Reproductive Barriers Cause Speciation Section 14.2 If the
potential to interbreed defines species, reproductive isolation
results in new species. Figure 14.5
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Reproductive Barriers Cause Speciation Section 14.2Figure 14.4
Prezygotic reproductive barriers occur before the formation of the
zygote, or fertilized egg. They prevent fertilization.
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Reproductive Barriers Cause Speciation Section 14.2 Postzygotic
reproductive barriers reduce the fitness of offspring produced by
members of two different species. They prevent the development of
fertile offspring. Figure 14.4
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Reproductive Barriers Cause Speciation Section 14.2Figure 14.24
Stilts: Tim Fitzharris/Minden Pictures; Sperm: Francis Leroy,
Biocosmos/Science Source; Chick: S. Alden/PhotoLink/Getty Images
RF; Stilt: USDA Natural Resources Conservation Service
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Clicker Question #2 Which of the following is an example of a
postzygotic reproductive barrier? A. A cross between a horse and a
donkey produces an infertile mule. B. Two types of fireflies lure
mates with different flash patterns. C. Bees pollinate one Mimulus
plant species; hummingbirds pollinate another. D. Pine sperm cannot
fertilize spruce eggs. Flower: Doug Sherman/Geofile/RF
Slide 12
Clicker Question #2 Which of the following is an example of a
postzygotic reproductive barrier? A. A cross between a horse and a
donkey produces an infertile mule. B. Two types of fireflies lure
mates with different flash patterns. C. Bees pollinate one Mimulus
plant species; hummingbirds pollinate another. D. Pine sperm cannot
fertilize spruce eggs. Flower: Doug Sherman/Geofile/RF
Slide 13
Spatial Patterns Define Three Types of Speciation Section
14.3Figure 14.5 Reproductive barriers arise in three ways,
depending on spatial patterns:
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Spatial Patterns Define Three Types of Speciation Section
14.3Figure 14.5 In allopatric speciation, a barrier physically
separates a population into two groups that cannot interbreed. With
no gene transfer between the two populations, each proceeds down
its own evolutionary line. Eventually, genetic differences between
the populations give rise to one or more reproductive
barriers.
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Spatial Patterns Define Three Types of Speciation Section
14.3Figure 14.7 For example, Galpagos tortoises diverged into
several subspecies on different islands. Left & right tortoise:
Tui De Roy/Minden Pictures
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Spatial Patterns Define Three Types of Speciation Section
14.3Figure 14.5 In parapatric speciation, part of a population
enters a new habitat bordering the range of the parent species.
Mating can occur between populations, but most individuals mate
with their own population. Genetic differences accumulate between
the populations, which may make interbreeding less likely.
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Spatial Patterns Define Three Types of Speciation Section
14.3Figure 14.8 Parapatric speciation may be occurring in little
greenbuls.
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Spatial Patterns Define Three Types of Speciation Section
14.3Figure 14.5 In sympatric speciation, populations diverge
genetically while sharing a habitat.
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Spatial Patterns Define Three Types of Speciation Section
14.3Figure 14.9 Cichlid fish have diversified into several species
in a small African lake. Each species specializes in a unique
micro- environment, leading to reproductive isolation and
speciation.
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Spatial Patterns Define Three Types of Speciation Section
14.3Figure 14.10 Sympatric speciation also occurs when gametes
unite to form polyploid offspring with more chromosomes than either
parent.
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Spatial Patterns Define Three Types of Speciation Section 14.3
A polyploid organism might form when gametes from two species
unite, producing the first cell of a new species. Figure 14.10
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Clicker Question #3 About 3 million years ago the Isthmus of
Panama closed, forming a land bridge connecting North and South
America. Snapping shrimp collected from water on one side of the
isthmus look similar to those on the other side, but they cannot
interbreed. What has occurred? A. allopatric speciation B.
parapatric speciation C. sympatric speciation Flower: Doug
Sherman/Geofile/RF
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Clicker Question #3 About 3 million years ago the Isthmus of
Panama closed, forming a land bridge connecting North and South
America. Snapping shrimp collected from water on one side of the
isthmus look similar to those on the other side, but they cannot
interbreed. What has occurred? A. allopatric speciation B.
parapatric speciation C. sympatric speciation Flower: Doug
Sherman/Geofile/RF
Slide 24
The Pace of Speciation Section 14.4 Figure 14.11 The fossil
record supports two hypotheses about the pace of evolution:
Gradualism Punctuated equilibrium
Slide 25
The Pace of Speciation Section 14.4 Gradualism suggests that
evolution proceeds in small, incremental changes over many
generations. Figure 14.11
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The Pace of Speciation Section 14.4 Punctuated equilibrium
suggests that long periods of little change are interrupted by
bouts of rapid change. Figure 14.11
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The Pace of Speciation Section 14.4 Bursts of speciation occur
during adaptive radiation: a population inhabiting a patchy or
heterogeneous environment gives rise to multiple specialized forms
in a relatively short time. Figure 14.11
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The Pace of Speciation Section 14.4 An adaptive radiation might
occur when a key adaptation arises. The first flowering plants, for
example, diversified quickly, as flowers provided a new options for
reproduction. Figure 14.11
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The Pace of Speciation Section 14.4Figure 14.13 Evolution might
also occur quickly following a mass extinction. The surviving
organisms exploit new resources in the changed environment.
Slide 30
14.4 Mastering Concepts Describe the theories of gradualism and
punctuated equilibrium. Island: Morandi Bruno/Hemis/Corbis
Slide 31
Section 14.5Figure 14.13 A species is extinct when all of its
members have died. Extinction Marks the End of the Line
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Section 14.5Figure 14.13 Most extinctions occur as part of the
background extinction rate, the pace at which species go extinct
due to gradually changing environments.
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Extinction Marks the End of the Line Section 14.5Figure 14.13
Earth has witnessed five mass extinctions in the last 600 million
years. During these periods, many species went extinct in a short
time.
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Extinction Marks the End of the Line Section 14.5Figure 14.12
Impact theory suggests that meteorites or comets caused some mass
extinctions. Rock: Francois Gohier/Science Source The debris
suspended in the atmosphere after a collision dramatically changed
the environment, leading to the extinction of many species.
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Extinction Marks the End of the Line Section 14.5 Plate
tectonics (Earths shifting land masses) also might explain mass
extinctions.
Slide 36
14.5 Mastering Concepts Distinguish between background
extinction and mass extinctions. Island: Morandi
Bruno/Hemis/Corbis
Slide 37
Biological Classification Systems Are Based on Common Descent
Section 14.6 Taxonomy is the science of describing, naming, and
classifying species. Figure 14.15
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Biological Classification Systems Are Based on Common Descent
Section 14.6 The taxonomic hierarchy organizes species into
progressively larger groups.
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Figure 14.16 Biological Classification Systems Are Based on
Common Descent Section 14.6 The more features two organisms have in
common, the more taxonomic levels they share. Squid: Frank &
Joyce Burek/Getty Images RF; Fly: Kimberly Hosey/Getty Images RF;
Orangutan: MedioImages/SuperStock RF; Chimp: Anup Shah/Getty Images
RF
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Biological Classification Systems Are Based on Common Descent
Section 14.6 Phylogenetics is the study of evolutionary
relationships among species.
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Biological Classification Systems Are Based on Common Descent
Section 14.6 Phylogenetic trees depict evolutionary relationships
based on descent from common ancestors. Species 1 Species 3 Species
8 Species 2 Species 4 Species 5 Species 6 Species 7 Species 9
Species 10 Common ancestor of species 1-10 Common ancestor of
species 6 & 7 Common ancestor of species 1-4
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Biological Classification Systems Are Based on Common Descent
Section 14.6Figure 14.17 A cladogram is a type of phylogenetic
tree. Clades
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Biological Classification Systems Are Based on Common Descent
Section 14.6Figure 14.17 A clade is a group of organisms consisting
of a common ancestor and all of its descendants. Clades
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Biological Classification Systems Are Based on Common Descent
Section 14.6Figure 14.17 Tracing taxa back to their common ancestor
reveals evolutionary relatedness. Clades
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Biological Classification Systems Are Based on Common Descent
Section 14.6Figure 14.17 According to this cladogram, a bird is
more closely related to a dinosaur than a crocodile. Clades
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Biological Classification Systems Are Based on Common Descent
Section 14.6Figure 14.17 We also know that turtles are more closely
related to lizards than to mammals.
Slide 47
Biological Classification Systems Are Based on Common Descent
Section 14.6Figure 14.17 Trace lineages from right to left until
they intersect to find their common ancestor.
Slide 48
Biological Classification Systems Are Based on Common Descent
Section 14.6Figure 14.17 Trace lineages from right to left until
they intersect to find their common ancestor.
Slide 49
Biological Classification Systems Are Based on Common Descent
Section 14.6Figure 14.17 The common ancestor that appears farther
to the right arose more recently.
Slide 50
Biological Classification Systems Are Based on Common Descent
Section 14.6Figure 14.17 A recent common ancestor means that
turtles and lizards are more closely related than turtles and
mammals.
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Clicker Question #4 What is the most recent common ancestor of
species 7, 8, and 9? Species 1 Species 3 Species 8 Species 2
Species 4 Species 5 Species 6 Species 7 Species 9 Species 10 D A C
B E Flower: Doug Sherman/Geofile/RF
Slide 52
Clicker Question #4 What is the most recent common ancestor of
species 7, 8, and 9? Species 1 Species 3 Species 8 Species 2
Species 4 Species 5 Species 6 Species 7 Species 9 Species 10 D A C
B E Flower: Doug Sherman/Geofile/RF
Slide 53
A Cladogram Can Be Drawn in Several Ways Section 14.6Figure
14.18 These cladograms all show the same evolutionary
relationships.
Slide 54
Identifying Groups in Cladograms Section 14.6Figure 14.21 A
clade is also called a monophyletic group.
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Identifying Groups in Cladograms Section 14.6Figure 14.21 A
paraphyletic group excludes some of the descendants of an ancestor.
See how birds are excluded?
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Identifying Groups in Cladograms Section 14.6Figure 14.21 A
polyphyletic group excludes the most recent common ancestor of its
members. Birds and mammals are endotherms, but their common
ancestor was not endothermic.
Slide 57
Clicker Question #5 Using the phylogenetic tree below, is
Protista a clade? A. Yes, because they all share a common ancestor.
B. No, because not all descendants from a common ancestor are
included in the group. Flower: Doug Sherman/Geofile/RF
Slide 58
Clicker Question #5 Using the phylogenetic tree below, is
Protista a clade? A. Yes, because they all share a common ancestor.
B. No, because not all descendants from a common ancestor are
included in the group. Flower: Doug Sherman/Geofile/RF
