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Sylv
ia S
. Ma
der
Copyright © The McGraw Hill Companies Inc. Permission required for reproduction or display
PowerPoint® Lecture Slides are prepared by Dr. Isaac Barjis, Biology Instructor
BIOLOGY 10th Edition
Speciation and Macroevolution
Chapter 17: pp. 299 - 316
1
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
(Stallion): © Superstock, Inc.; (Donkey): © Robert J. Erwin/Photo
Researchers, Inc.; (Mule): © Jorg & Petra Wegner/Animals
Animals/Earth Scenes;
mating
fertilization
horse
Parents
Offspring
donkey
mule (hybrid)
Usually
mules cannot
reproduce.
If an
offspring
does result,
it cannot
reproduce.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Ensatina eschscholtzi picta
Ensatina eschscholtzi platensis
1
2
3
Members of a northern ancestral
population migrated southward.
Ensatina eschscholtzi
oregonensis
Subspecies are separated by
California’s Central Valley .Some
interbreeding between populations
does occur.
Ensatina eschscholtzi
xanthoptica Ensatina eschscholtzi
croceater
Ensatina eschscholtzi
eschscholtzii
Ensatina eschscholtzi
klauberi Evolution has occurred, and in
the south, subspecies do not
interbreed even though they
live in the same environment.
Central
Valley
Barrier
2
Outline
Separation of the Species
Modes of Separation
Allopatic speciation
Adaptive radiation
Sympatric speciation
Macroevolution
3
Separation of the Species
Macroevolution is best observed within
the fossil record,
Requires the origin of species, also called
speciation.
Speciation is the final result of changes in
gene pool allelic and genotypic frequencies.
4
Species Definitions
Every species has its own evolutionary
history
Binomial nomenclature, is used to name
various species
The two-part scientific name, when translated
from the Latin, often tells you something about
the organism.
Scientific name of the dinosaur, Tyrannosaurus rex,
means “tyrant-lizard king.”
5
Species Definitions
Evolutionary species concept distinguish
species from one another based on:
Morphological (structural) traits,
Biological species concept relies
primarily on reproductive isolation rather
than trait differences to define a species.
6
Species Definitions
Species Definitions
Morphological
Can be distinguished anatomically
Specialist decides what criteria probably represent
reproductively isolated populations
Most species described this way
7
Evolutionary Species Concept
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Orcinus orca
Rodhocetus kasrani
Ambulocetus natans
Pakicetus attocki
Hindlimbs too
reduced for walking
or swimming
Hindlimbs used
for both walking
on land and
paddling in water
Tetrapod with limbs
for walking
8
Species Definitions
Species Definitions
Biological
Populations of the same species breed only among
themselves
Are reproductively isolated from other such
populations
Very few actually tested for reproductive isolation
9
Biological Species Concept
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
pit-see fitz-bew
Acadian flycatcher , Empidonax virescens Willow flycatcher, Empidonax trailli Least flycatcher, Empidonax minimus
(Acadian): © Karl Maslowski/Visuals Unlimited; (Willow): © Ralph Reinhold/Animals Animals/Earth Scenes; (Least): © Stanley Maslowski/Visuals Unlimited.
che-bek or che-bek
10
Human Populations
(Left): © Sylvia S. Mader; (Right): © B & C Alexander/Photo Researchers, Inc.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
11
Reproductive Isolating Mechanisms
Reproductive isolating mechanisms inhibit gene flow between species
Two general types:
(1) Prezygotic Mechanisms – prevents matting attempts Habitat Isolation - species occupy different habitats,
Temporal Isolation - each reproduces at a different time
Behavioral Isolation
Mechanical Isolation
Gamete Isolation
12
Reproductive Barrier
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Mating Premating
Postzygotic Isolating Mechanisms Prezygotic Isolating Mechanisms
Fertilization
species 1
species 2
Habitat isolation Species at same locale
occupy different habitats.
Temporal isolation Species reproduce at
different seasons or
different times of day.
Behavioral isolation In animal species,
courtship behavior differs,
or individuals respond to
different songs, calls,
pheromones, or other
signals.
Gamete isolation Sperm cannot reach
or fertilize egg.
Mechanical isolation Genitalia between
species are unsuitable
for one another.
Zygote mortality Fertilization occurs, but
zygote does not survive.
Hybrid sterility Hybrid survives but is
sterile and cannot
reproduce.
F2 fitness Hybrid is fertile, but F2 hybrid
has reduced fitness.
hybrid
offspring
13
Temporal Isolation
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
high
low
Ma
tin
g A
cti
vit
y
March 1 April 1 May 1 June 1 July 1
14
Prezygotic Isolating Mechanism
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
© Barbara Gerlach/Visuals Unlimited
15
Reproductive Isolating Mechanisms
Two general types:
(2) Postzygotic Mechanisms - Prevent hybrid
offspring from developing or breeding
Zygote Mortality
Hybrid Sterility
Reduced F2 Fitness
16
Postzygotic Isolating Mechanism
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
(Stallion): © Superstock, Inc.; (Donkey): © Robert J. Erwin/Photo Researchers, Inc.; (Mule): © Jorg & Petra Wegner/Animals Animals/Earth Scenes;
mating
fertilization
horse
Parents
Offspring
donkey
mule (hybrid)
Usually
mules cannot
reproduce.
If an
offspring
does result,
it cannot
reproduce.
17
Modes of Speciation
Speciation: The splitting of one species into two, or The transformation of one species into a new
species over time
Two modes: (1) Allopatric Speciation
Two geographically isolated populations of one species
Become different species over time Can be due to differing selection pressures in
differing environments
18
Allopatric Speciation
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Ensatina eschscholtzi picta
Ensatina eschscholtzi platensis
1
2
3
Members of a northern ancestral
population migrated southward.
Ensatina eschscholtzi
oregonensis
Subspecies are separated by
California’s Central Valley .Some
interbreeding between populations
does occur.
Ensatina eschscholtzi
xanthoptica Ensatina eschscholtzi
croceater
Ensatina eschscholtzi
eschscholtzii
Ensatina eschscholtzi
klauberi Evolution has occurred, and in
the south, subspecies do not
interbreed even though they live
in the same environment.
Central
Valley
Barrier
19
Allopatric Speciation
Salmon that matured at Pleasure Point Beach do not reproduce with those that matured in the Cedar River.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Lake female
Lake male River male
River female
a. Sockeye salmon at Pleasure Point Beach, Lake Washington b. Sockeye salmon in Cedar River .The river connects with
Lake Washington.
20
Modes of Speciation
Two modes:
(2) Sympatric Speciation
One population develops into two or more
reproductively isolated groups
No prior geographic isolation
It involves polyploidy (a chromosome number
beyond the diploid [2n] number)
Tetraploid hybridization in plants
Results in self fertile species
Reproductively isolated from either parental species
21
Modes of Speciation
(2) Sympatric Speciation
A polyploid plant can reproduce with itself, but cannot
reproduce with the 2n population because not all the
chromosomes would be able to pair during meiosis.
Two types of polyploidy are known:
Autoploidy - diploid plant produces diploid gametes due to
nondisjunction during meiosis.
If diploid gamete fuses with a haploid gamete, a triploid plant
results.
A triploid (3n) plant is sterile and cannot produce offspring
because the chromosomes cannot pair during meiosis.
Alloploidy - more complicated process than autoploidy
Requires two different but related species of plants
Hybridization is followed by doubling of the chromosomes.
Alloploidy
22
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
seeds
polyploid
banana
diploid
banana (2n)
no
seeds
23
Autoploidy
Clarkia concinna Clarkia virgata
hybrid
2n = 14 2n = 10
2n = 24
doubling of chromosome number
Clarkia pulchella
(C. pulchella): © J. L. Reveal; (C. concinna): © Gerald & Buff Corsi/Visuals Unlimited; (C. virgata): ©: Dr. Dean Wm. Taylor/Jepson Herbarium, UC Berkeley
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
24
Adaptive Radiation
Adaptive Radiation
When members of a species invade several new geographically separate environments
The populations become adapted to the different environments
Many new species evolve from the single ancestral species
This is an example of allopatric speciation
25
Adaptive Radiation
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Amakihi
Akepa
Akiapolaau
Nukupuu
* Akialoa
* Extinct species or subspecies
Maui parrot bill
Palila
Ou
* Lesser Koa finch
Laysan
finch * Greater
Koa finch
* Kona
finch
* Kauai
akialoa
Alauwahio
(Hawaiian
creeper)
Anianiau
(lesser
amakihi)
Great
amakihi
(green
solitaire)
Genus Loxops
26
Principles of Macroevolution
Macroevolution
Evolution at the species or higher level of
classification
Occurs gradually
Evolutionists support a gradualistic model
Speciation occurs after populations become
isolated
Each group continuing its own evolutionary pathway
The gradualistic model suggests that it is difficult to
indicate when speciation occurred
27
Principles of Macroevolution
Macroevolution
Some paleontologists believe that
Species can appear quite suddenly
Remain essentially unchanged phenotypically
during a period of stasis (sameness) until they
undergo extinction.
Based on these findings, they developed a
punctuated equilibrium model to explain the pace of
evolution.
28
Gradualistic and Punctuated
Equilibrium Models Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
transitional link
a. Gradualistic model b. Punctuated equilibrium
stasis
new
species 1
new
species 1
ancestral
species
ancestral
species
ancestral
species
new
species 2
new
species 2
Time Time
29
Developmental Genes and
Macroevolution
Genes can bring about radical changes in
body shapes and organs.
Gene Expression Can Influence Development
A change in gene expression could stop
developmental process or continue it beyond its
normal time.
Using modern technology researchers discovered
genes whose differential expression can bring about
changes in body shapes and organs.
30
Pax6 Gene and Eye Development
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
(Left): © Carolina Biological Supply/Photo Researchers, Inc.; (Center): © Vol. OS02/PhotoDisc/Getty Images; (Right): © Aldo Brando/Peter Arnold, Inc.
31
Study of Pax6 Gene
Courtesy Walter Gehring, reprinted with permission from Induction of Ectopic Eyes by Target Expression of the Eyeless Gene in Drosophila, G. Halder, P. Callaerts, Walter J. Gehring, Science Vol. 267, © 24
March 1995 American Association for the Advancement of Science
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
32
Hox6 Gene
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
(Both): © A. C. Burke, 2000
33
Macroevolution Is Not Goal-Oriented
The evolution of the horse (Equus)
Studied since the 1870s
Model for gradual, straight-line evolution
Modern horse, had been achieved as a goal
Three trends were particularly evident during
the evolution:
Increase in overall size,
Toe reduction, and
Change in tooth size and shape.
34
Simplified Family Tree of Equus
2 MYA
4 MYA
12 MYA
15 MYA
17 MYA
23 MYA
25 MYA
35 MYA
40 MYA
45 MYA
50 MYA
55 MYA
Equus
Dinohippus
Neohipparion Hipparion
Megahippus
Miohippus
Palaeotherium
Hyracotherium
Merychippus
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
35
Review
Separation of the Species
Modes of Separation
Allopatic speciation
Adaptive radiation
Sympatric speciation
Macroevolution
Sylv
ia S
. Ma
der
Copyright © The McGraw Hill Companies Inc. Permission required for reproduction or display
PowerPoint® Lecture Slides are prepared by Dr. Isaac Barjis, Biology Instructor
BIOLOGY 10th Edition
Speciation and Macroevolution
Chapter 17: pp. 299 - 316
36
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
(Stallion): © Superstock, Inc.; (Donkey): © Robert J. Erwin/Photo
Researchers, Inc.; (Mule): © Jorg & Petra Wegner/Animals
Animals/Earth Scenes;
mating
fertilization
horse
Parents
Offspring
donkey
mule (hybrid)
Usually
mules cannot
reproduce.
If an
offspring
does result,
it cannot
reproduce.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Ensatina eschscholtzi picta
Ensatina eschscholtzi platensis
1
2
3
Members of a northern ancestral
population migrated southward.
Ensatina eschscholtzi
oregonensis
Subspecies are separated by
California’s Central Valley .Some
interbreeding between populations
does occur.
Ensatina eschscholtzi
xanthoptica Ensatina eschscholtzi
croceater
Ensatina eschscholtzi
eschscholtzii
Ensatina eschscholtzi
klauberi Evolution has occurred, and in
the south, subspecies do not
interbreed even though they
live in the same environment.
Central
Valley
Barrier