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Welcome
Introduce Zoology
Syllabus
Lecture
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Evolution, and Zoology
Theory of Evolution by Natural Selection
Origin of Species
Properties of Life Origins of Life
Prokaryotic and Eukaryotic
Levels of organization
Cell division and inheritance
• Biology is the study of Life
• Single cell to multicellular organisms
• Cell is the basic unit of life
• Unique plant cell and animal cell
• Zoology- zoon, animal + logos, to study
– is the study of Animals
• Is one of the broadest fields in all of science
– Variety of animals
– Complexity of and the processes
Specializations in Zoology
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Anatomy
Ecology
Genetics
Parasitology
Physiology
• Entomology• Ichthyology-
Ichthyologistwork to understand structure, function, ecology and
evolution of fishes
Studies have uncovered an amazing diversity of fishes
Cichlid (‘sick-lid’)- freshwater fishes
• 1000 species in Africa
• 300 in South America
• 3 in India
• 1 in North America
Animal classification and Evolutionary Relationship
• Evolution not only explanation why animals appear
and function as they do
• It explains family relationships
• i.e cichlid species
– Groups share more of their DNA
– Thus resemble each other
– Genetic studies suggest
• Oldest African cichlid found in Lakes Tanganyika and Kivu
• These fish invades rivers, lakes Malawi, Victoria and others
• Most rapid known origin of species of any animal groups
Members of this group
• Variety of color patterns
• Habitats
• Body forms
• Feeding habits
Binomial nomenclature
• Karl von Linne also known as Carolus Linnaeus
(1707-1778)
• Named and classified plants into hierarchy of relatedness
• Binomial Nomenclature- systematic way of naming
organisms– Two part name describes each kind of organism
– First part- indicates the genus
– Second part indicates the species to which the organism belongs.
– i.e. Perissodus microlepis
Field of taxonomy [Gk. taxis, arrange, put in order + nomos, law].
Figure 1.4
Hierarchy of Relatedness
Eretmodus
Nip algae with chisel-like teeth
Tanganicodus
Insect pickers
Perissodus
Scale eaters
• Brood their young
• Dogtooth cichlid
The Fontosa
Body form
An Evolutionary Perspective
• Share a common evolutionary past and evolutionary
forces that influence their history
– Resulted in 4 to 100 million species of animals
• Understand evolutionary process to understand
– What it is
– How it originated
• Evolutionary concepts hold the key to understanding
– why animals look and act
– Habitat
– Characteristics
Ecological Perspective
• Ecology- (Gr. okois, house + logos, to study)
• Study of the relationships between organisms and
their environment
• Human dependence on animals (food, medicine,
clothing)
• Humans upset the delicate ecological balances that
has evolved
In the 1950’s in an attempt to increase the lake’s fishery
• Nile perch introduced into Lake
Victoria
• Reduced cichlid population from 99%
to <1%
• Most cichlid feed on algae, the algae
grew
• Algae died and decayed
• Lake depleted of oxygen
• Introduced nonnative plant (water
hyacinth)
• Water hyacinth has overgrown and
resulted in further habitat loss
• Darwins nitemare
• Fishhead video Nile perch
• The Darwinian revolution challenged traditional
views of a young Earth inhabited by unchanging
species
• In order to understand why Darwin’s ideas were
revolutionary
– We need to examine his views in the context of other
Western ideas about Earth and its life
• 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
Lamarck’s Theory of Evolution
• Lamarck hypothesized that species evolve
– Through use and disuse and the inheritance of acquired traits
• Environmental changes generate new needs
• These needs determine the use or disuse of some organs
• Such organs develop or are diminished
• The acquired characters are hereditary
– But the mechanisms he proposed are unsupported by evidence
functions create organs and heredity
determines the change in offspring
Fossils, Cuvier, and
Catastrophism
• The study of fossils
– Helped to lay the groundwork for Darwin’s ideas
• Fossils are remains or traces of organisms from
the past
– Usually found in sedimentary rock, which appears in
layers or strata
• 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
HMS Beagle in port
SOUTH
AMERICA
AUSTRALIA
Andes
Darwin in 1840,
after his return
AFRICA
Cape of
Good Hope
Cape Horn
Tierra del Fuego
Tasmania
New
Zealand
Darwin’s Focus on Adaptation
• As Darwin reassessed all that he had observed during
the voyage of the Beagle
– He began to perceive adaptation to the environment and
the origin of new species as closely related processes
• From studies made years after Darwin’s voyage
– Biologists have concluded that this is indeed what
happened to the Galápagos finches
(a) Cactus eater. The long,
sharp beak of the cactus
ground finch (Geospiza
scandens) helps it tear
and eat cactus flowers
and pulp.
Figure 22.6a–c
(c) Seed eater. The large ground
finch (Geospiza magnirostris)
has a large beak adapted for
cracking seeds that fall from
plants to the ground.
(b) Insect eater. The green warbler
finch (Certhidea olivacea) uses its
narrow, pointed beak to grasp insects.
• In 1844, Darwin wrote a long essay on the origin
of species and natural selection
– But he was reluctant to introduce his theory publicly,
anticipating the uproar it would cause
• In June 1858 Darwin received a manuscript from
Alfred Russell Wallace
– Who had developed a theory of natural selection
similar to Darwin’s
• Darwin quickly finished The Origin of Species
– And published it the next year
Evolutionary Processes
• Organic evolution- change in the genetic makeup of
populations over time.
– Source of animal diversity
– Explains family relationships within animal groups
• Charles Darwin
• Published The Origin of Species- evidence of
evolution in 1859
• Proposed a mechanism
• Understanding diversity of animal structure and
function arose is one of the many challenges
• i.e cichlid scale eaters of Africa
Resistance to the Idea of Evolution
• The Origin of Species
– Focused biologists’ attention on the great diversity of
organisms
– Shook the deepest roots of Western culture
– Challenged a worldview that had been prevalent for
centuries
• 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
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
– With multiple branchings from a common trunk to the
tips of the youngest twigs that represent the diversity of
living organisms
Sirenia
Hyracoidea (Manatees
(Hyraxes)and relatives)
ElephasLoxodontaLoxodonta
maximus africana cyclotis
(Asia) (Africa) (Africa)
phylogenetic tree (Gk. phylon, stock, tribe + genus, birth, origin):
Wolf
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
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
• Natural selection can produce an increase over time
– In the adaptation of organisms to their environment
(a) A flower mantid
in Malaysia
(b) A stick mantid
in Africa
Figure 22.11
• If an environment changes over time
– Natural selection may result in adaptation to these new
conditions
• Darwin’s theory explains a wide range of
observations
• Darwin’s theory of evolution
– Continues to be tested by how effectively it can
account for additional observations and experimental
outcomes
Homology, Biogeography, and
the Fossil Record
• Evolutionary theory
– Provides a cohesive explanation for many kinds of observations
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We will explore these key questions:
What is homology?
How do we identify anatomical homologies?
What do genes do? How do genes control other genes to build complex
structures like eyes?
How can genes be homologous?
Anatomical Homologies
• Homologous structures between organisms
– Are anatomical resemblances that represent variations on
a structural theme that was present in a common ancestor
Homology
Is similarity resulting from
common ancestry
Human Cat
Whale
Bat
• Comparative embryology
– Reveals additional anatomical homologies not visible in
adult organisms
Pharyngeal
pouches
Post-anal
tail
Chick embryo
Figure 22.15
Human embryo
• Vestigial organs
– Are some of the
most intriguing
homologous
structures
– Are remnants of
structures that
served important
functions in the
organism’s
ancestors
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
Homologies and the Tree of
Life
• The Darwinian concept of an evolutionary tree of life
– Can explain the homologies that researchers have
observed
• 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%
Biogeography
• Darwin’s observations of the geographic distribution
of species, biogeography
– Formed an important part of his theory of evolution
• Some similar mammals that have adapted to similar
environments
– Have evolved independently from different ancestors
NORTH
AMERICA
Sugar
glider
AUSTRALIA
Flying
squirrel
Figure 22.17
The Fossil Record
• The succession of forms observed in the fossil record
– Is consistent with other inferences about the major
branches of descent in the tree of life
• 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
• 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