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Evolutionary Patterns, Rates,
and Trends
AP Biology:
Chapter 19
Starr & Taggart – 11th Edition
Key Concepts:

All species that have ever lived are
related

Macroevolution refers to patterns,
trends, and rates of change among
lineages over geologic time

Fossil and geologic records and
radiometric dating of rocks provide
evidence of macroevolution
Chapter 19
Key Concepts:

Anatomical comparisons help
reconstruct patterns of change
through time

Biochemical comparisons also
provide evidence of macroevolution

Diversity characterizes the
distribution of species through time

Taxonomy is concerned with
identifying and naming new species
Chapter 19
Macroevolution

Large scale patterns,
trends and rates of
change among families
and other more
inclusive groups of
species.
Chapter 19
What is a Species?
A mixed herd of zebroids & horses.
Zebroids – are interspecies hybrids (horses & zebras)
Chapter 19
♂ & ♀ fish

Morphological Species Concept


What is a Species?
Based on appearance alone
Biological Species Concept

A species is one or more
populations of individuals that
are interbreeding under natural
conditions and producing fertile
offspring, and are reproductively
isolated from other such
populations
Chapter 19
Two
plants
of the
same
species
Species Example

Lions and
tigers do not
meet in the
wild, so don’t
interbreed;
in captivity
can mate to
produce a
liger (sterile)
Chapter 19
Reproductive Isolation
Cornerstone of the biological species
concept
 Speciation is the attainment of
reproductive isolation
 Reproductive isolation arises as a
by-product of genetic change

Chapter 19
Reproductive Isolating
Mechanisms

Any heritable feature of body, form,
functioning, or behavior that prevents
breeding between one or more genetically
divergent populations

Prezygotic or Postzygotic
PrezygoticMechanical isolation
Chapter 19
Types of Isolation
Chapter 19
Isolating
Mechanisms
Chapter 19
Temporalcicada

Pre-Zygotic
Isolation
Mating or zygote formation is
blocked

Temporal Isolation

Behavioral Isolation

Mechanical Isolation

Ecological Isolation

Gamete Mortality
Chapter 19
Behavioral - albatross
Post-Zygotic Isolation

Takes effect after hybrid zygotes form



Zygotic mortality - Egg is fertilized but
zygote or embryo dies
Hybrid inviability - First generation hybrid
forms but shows low fitness
Hybrid infertility - Hybrid is fully or
partially sterile
Chapter 19
Genetic Divergence



Gradual accumulation of differences in the
gene pools of genetically separated
populations
Natural selection, genetic drift and
mutation can contribute to divergence
Gene flow counters genetic divergence
Chapter 19
Mechanisms of Speciation

Allopatric speciation

Sympatric speciation

Parapatric speciation
Chapter 19
Allopatric Speciation

Physical barrier
prevents gene flow
between
populations of a
species


Effectiveness of
barrier varies with
species
Archipelago hotbed
of speciation
Chapter 19
Allopatric Speciation on
Archipelagos (Island
Chain)
Chapter 19
Hawaiian Honeycreepers
Hawaiian
Honeycreepers
Chapter 19
Allopatric Speciation

Physical separation between
populations promotes genetic changes
that eventually lead to speciation.
Chapter 19
Speciation without a Barrier

Sympatric speciation


Species form within the home range of
the parent species
Parapatric speciation

Neighboring populations become
distinct species while maintaining
contact along a common barrier
Chapter 19
Sympatric Speciation

New species forms within home range


Polyploidy leads to speciation in plants
Self-fertilization and asexual reproduction
Chapter 19
Sympatric Speciation

A species forms within the home
range of an existing species, in the
absence of a physical barrier.
A lake in West Africa
in which 9 species of
cichlids (a small
fish)
evolved.
Chapter 19
Speciation by Polyploidy

Change in chromosome number
(3n, 4n, etc.)

Offspring with altered
chromosome number cannot
breed with parent population

Common mechanism of
speciation in flowering plants
Polyploidy cotton
Chapter 19
Allopatric
vs.
Sympatric
Speciation
Chapter 19
Parapatric Speciation

Bullock’s
oriole
Neighboring
populations become
distinct species while
maintaining contact
along a common
border, the hybrid
zone.
Baltimore
oriole
Chapter 19
Models of Speciation
Models of speciation
Chapter 19
Patterns of Change
in a Lineage

Cladogenesis
Branching pattern
 Lineage splits, isolated populations
diverge


Anagenesis
No branching
 Changes occur within single lineage
 Gene flow throughout process

Chapter 19
Evolutionary Trees
extinction
(branch
ended
before
present)
new species
branch point
(a time of
divergence,
speciation)
a single
lineage
branch point
(a time of
divergence,
speciation)
a new
species
a single
lineage
Chapter 19
dashed line
(only sketchy
evidence of
presumed
evolutionary
relationship)
Gradual Model
Time


Punctuated
equilibrium
Gradualism
Chapter 19
Speciation model
in which species
emerge through
many small
morphological
changes that
accumulate over a
long time period
Fits well with
evidence from
certain lineages in
fossil record
Punctuation Model


Speciation model
in which most
changes in
morphology are
compressed into
brief period near
onset of
divergence
Supported by
fossil evidence in
some lineages
Chapter 19
Adaptive Radiation




Burst of
divergence
Single lineage
gives rise to many
new species
New species fill
vacant adaptive
zone
Adaptive zone is
“way of life”
Chapter 19
Extinction
Irrevocable loss of a species
 Mass extinctions have played a major
role in evolutionary history
 Fossil record shows 20 or more largescale extinctions
 Reduced diversity is followed by
adaptive radiation

Chapter 19
Who Survives?



Species survival is to some extent random
Asteroids have repeatedly struck Earth,
destroying many lineages
Changes in global temperature favor
lineages that are widely distributed
Mass
extinctions
Chapter 19
Identifying Species
Past and Present

Taxonomy – field of biology concerned with
identifying, naming and classifying species

Somewhat subjective

Devised by Carl von Linne

Assigning species names


Binomial nomenclature system

Genus (generic) and Species (specific)
Higher Taxa

Family, Order, Class, Phylum, and Kingdom
Chapter 19
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
Chapter 19
Examples of Classification
Chapter 19
How Many Kingdoms?

Whittaker’s Five-Kingdom Scheme (1969)

Monera

Protista

Fungi

Plantae

Animalia
Chapter 19
Six Kingdom Scheme

Carl Woese

Eubacteria
Includes the Archaebacteria
Archaebacteria
Protista
Chapter 19
Fungi
Plantae
Animalia
Three Domain Scheme

Favored by microbiologists
Eubacteria
 Archaebacteria
 Eukaryotes

EUBACTERIA
(Bacteria)
ARCHAEBACTERIA
(Archaea)
Chapter 19
EUKARYOTES
(Eukarya)
Taxon
Traits (Characters)
Jaws Limbs Hair Lungs Tail Shell
Constructing
A
Cladogram
Lamprey
Turtle
Cat
Gorilla
Lungfish
Trout
Human
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Taxon
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Traits (Characters)
Jaws Limbs Hair Lungs Tail Shell
Please note: the tail
column was changed as
it was incorrect in the
text.
Lamprey
Turtle
Cat
Gorilla
Lungfish
Trout
Human
Chapter 19
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Constructing a Cladogram
turtle, gorilla, trout, cat,
lungfish, human
lamprey
jaws
Chapter 19
Constructing a Cladogram
lamprey
turtle, gorilla, cat,
lungfish, human
trout
lungs
jaws
Chapter 19
Constructing a Cladogram
lamprey
trout
lungfish
turtle, gorilla, cat, human
limbs
lungs
jaws
Chapter 19
Constructing a Cladogram
lamprey
trout
lungfish
turtle
gorilla, cat, human
hair
limbs
lungs
jaws
Chapter 19
Constructing a Cladogram
lamprey
trout
lungfish
turtle
cat
gorilla
human
tail loss
hair
limbs
lungs
jaws
Chapter 19
A Cladogram
Constructing a Cladogram
Chapter 19
Evolutionary Tree
PLANTS
flowering plants conifers
ginkgos
cycads
horsetails
ferns
FUNGI
sac club
fungi fungi
zygosporeforming
fungi
lycophytes
ANIMALS
arthropods chordates
annelids
roundechinomollusks
worms
derms
rotifers
flatworms
cnidarians
bryophytes
chlorophytes
(stramenopiles)
brown algae
chrysophytes
oomycotes
sponges
chytrids
green algae amoeboid
protozoans
red
algae
slime molds
?
crown of eukaryotes
(rapid divergences)
PROTISTANS
ciliates (alveolates)
sporozoans
dinoflagellates
euglenoids
kinetoplastids
parabasalids
(e.g., Trichomonas)
ARCHAEBACTERIA diplomonads
extreme (e.g., Giardia) Gram-positive bacteria
halophiles
methanogens
cyanobacteria
extreme
thermophiles
molecular origin of life
Chapter 19
EUBACTERIA
spirochetes
chlamydias
proteobacteria
In Conclusion




Macroevolution is the study of patterns,
trends, or rates of change among groups
of species over long periods of time
There is extensive evidence of evolution
based on similarities and differences in
body form, function, behavior, and
biochemistry
Completeness of fossil records are
variable
Fossil and geologic record show that such
changes have influenced evolution
Chapter 19
In Conclusion

Comparative morphology reveals
similarities in embryonic
development and identified
homologous structures

Comparative biochemistry has
identified similarities and differences
among species

Taxonomists identify, name, and
classify speciesChapter 19