Evolution and systematics.ppt

Descent with Modification: A
Darwinian View of Life
PowerPoint Lectures for
Biology, Seventh Edition
Neil Campbell and Jane Reece

Lectures by Chris Romero
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

•  The Origin of Species
–  Focused biologists’ attention on the great
diversity of organisms

Figure 22.1

•  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


•  The historical context of Darwin’s life and
ideas
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)
American Revolution
1750

Wallace (evolution, natural selection)
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.
1837 Darwin begins his notebooks on the origin of species.
1844 Darwin writes his essay on the origin of species.
1858 Wallace sends his theory to Darwin.
1859 The Origin of Species is published.
1865 Mendel publishes inheritance papers.

Figure 22.2

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


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


•  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”


Theories of Gradualism
•  Gradualism
–  Is the idea that profound change can take
place through the cumulative effect of slow but
continuous processes


•  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


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

•  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
England
NORTH
AMERICA

EUROPE

ATLANTIC
OCEAN

PACIFIC
OCEAN
Galápagos
Islands

AUSTRALIA
Cape of
Good Hope
Cape Horn

Figure 22.5

HMS Beagle in port

SOUTH
AMERICA
Andes

Darwin in 1840,
after his return

AFRICA

Tierra del Fuego


Tasmania
New
Zealand

The Origin of Species
•  Darwin developed two main ideas
–  Evolution explains life’s unity and diversity
–  Natural selection is a cause of adaptive
evolution


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


•  In the Darwinian view, the history of life is like a tree

Sirenia
Hyracoidea (Manatees
(Hyraxes) and relatives)

Figure 22.7

Mammuthus

Stegodon

Platybelodon

Mammut

Barytherium

Deinotherium

Elephas Loxodonta Loxodonta
maximus africana
cyclotis
(Africa)
(Asia)
(Africa)

Moeritherium

Millions of years ago

Years ago

–  With multiple branchings from a common trunk
to the tips of the youngest twigs that represent
the diversity of living organisms

Natural Selection and Adaptation
•  Evolutionary biologist Ernst Mayr
–  Has dissected the logic of Darwin’s theory into
three inferences based on five observations


•  Observation #1: For any species, population
sizes would increase exponentially
–  If all individuals that are born reproduced
successfully

Figure 22.8


•  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

•  Observation #4: Members of a population vary
extensively in their characteristics
–  No two individuals are exactly alike

Figure 22.9

•  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


•  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


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
Terminal
bud

Lateral
buds
Brussels sprouts

Cabbage

Flower
cluster

Leaves

Cauliflower

Kale

Flower
and
stems
Broccoli

Stem
Wild mustard

Figure 22.10

Kohlrabi

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


•  If an environment changes over time
–  Natural selection may result in adaptation to
these new conditions


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


•  Researchers have developed numerous drugs
to combat HIV

Percent of HIV resistant to 3TC

–  But using these medications selects for
viruses resistant to the drugs
Patient
No. 1
Patient No. 2

Patient No. 3

Weeks

Figure 22.13

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


•  Anatomical resemblances among species
–  Are generally reflected in their molecules, their
genes, and their gene products
Species

Percent of Amino Acids That Are
Identical to the Amino Acids in a
Human Hemoglobin Polypeptide
100%

Human
Rhesus monkey

95%

Mouse

87%

Chicken

69%

Frog

Figure 22.16

Lamprey


54%

14%

•  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

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


•  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


Previous Taxonomic Systems
•  Early classification systems had two kingdoms
–  Plants and animals


•  Robert Whittaker proposed a system with five
kingdoms
–  Monera, Protista, Plantae, Fungi, and Animalia

Plantae

Fungi

Protista

Figure 26.21

Monera

Animalia

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


Figure 26.22

Domain Archaea

Domain Bacteria

Universal ancestor
Domain Eukarya

Charophyceans

Chlorophytes

Red algae

Cercozoans, radiolarians

Stramenopiles (water molds, diatoms, golden algae, brown algae)

Chapter 27

Alveolates (dinoflagellates, apicomplexans, ciliates)

Euglenozoans

Diplomonads, parabasalids

Euryarchaeotes, crenarchaeotes, nanoarchaeotes

Korarchaeotes

Gram-positive bacteria

Cyanobacteria

Spirochetes

Chlamydias

Proteobacteria

•  One current view of biological diversity
Chapter 28

Figure 26.21

Plants

Fungi
Animals

Bilaterally symmetrical animals (annelids,
arthropods, molluscs, echinoderms, vertebrates)

Cnidarians (jellies, coral)

Chapter 32
Sponges

Chapter 31
Choanoflagellates

Club fungi

Sac fungi

Chapter 28
Arbuscular mycorrhizal fungi

Zygote fungi

Chytrids

Chapter 30
Amoebozoans (amoebas, slime molds)

Angiosperms

Gymnosperms

Seedless vascular plants (ferns)

Bryophytes (mosses, liverworts, hornworts)

Chapter 29
Chapters 33, 34

•  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


Binomial Nomenclature
•  Binomial nomenclature
–  Is the two-part format of the scientific name of
an organism
–  Was developed by Carolus Linnaeus


•  The binomial name of an organism or scientific
epithet
–  Is latinized
–  Is the genus and species


Hierarchical Classification
•  Linnaeus also introduced a system
–  For grouping species in increasingly broad
categories
Panthera
Species pardus
Panthera

Genus

Felidae

Family

Carnivora

Order
Class
Phylum
Kingdom

Figure 25.8

Domain


Mammalia
Chordata
Animalia
Eukarya

Linking Classification and Phylogeny
•  Systematists depict evolutionary relationships

Species

Panthera

Order

Family

Panthera
Mephitis
Canis
Canis
Lutra lutra
pardus
mephitis
familiaris
lupus
(European
(leopard) (striped skunk)
otter) (domestic dog) (wolf)

Genus

–  In branching phylogenetic trees

Mephitis

Felidae

Lutra

Mustelidae

Carnivora

Figure 25.9

Canis

Canidae

•  Each branch point
–  Represents the divergence of two species

Leopard

Domestic cat

Common ancestor

•  “Deeper” branch points
–  Represent progressively greater amounts of
divergence

Wolf

Leopard

Common ancestor

Domestic cat

•  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

Cladistics
•  Clades
–  Can be nested within larger clades, but not all
groupings or organisms qualify as clades


•  A valid clade is monophyletic
–  Signifying that it consists of the ancestor
species and all its descendants
Grouping 1
E

D

J

H

G
F

C

K
I

B
A

Figure 25.10a

(a) Monophyletic. In this tree, grouping 1,
consisting of the seven species B–H, is a
monophyletic group, or clade. A monophyletic 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.


•  A paraphyletic clade
–  Is a grouping that consists of an ancestral
species and some, but not all, of the
descendants
Grouping 2
G

E

D
C

J

H

K
I

F

B
A

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.)


•  A polyphyletic grouping
–  Includes numerous types of organisms that
lack a common ancestor
Grouping 3
D

E

G

J

H

I

F

C

K

B
A

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. Furthermore, 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.


Shared Primitive and Shared Derived Characteristics

•  In cladistic analysis
–  Clades are defined by their evolutionary
novelties


•  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


•  A shared derived character
–  Is an evolutionary novelty unique to a particular
clade


TAXA

A

B

C

D

E
Apomorphy
for taxon D

Apomorphies
for taxa B&C
TIME

Apomorphy
for taxa B-F

Cladogram or Phylogenetic Tree

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 reestablishment of ancestral feature.

Convergence - Stem succulence and “spines” in
Cactaceae and Euphorbia spp.

Evolution and systematics.ppt

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