Transcript Biology CP- Chapter 14 & 15 evolution notes

Darwin’s Theory of
Evolution
Concept 14.1 pp. 292-298
Pre-Darwin IdeasThat species are fixed, permanentunchanging.
The Earth was less than 10,000 yrs. old
and relatively unchanging.
These ideas were challenged as people
became aware of diversity of plants,
animals and the geological processes of
Earth.
Evolution

the biological history of life.
All the changes that transformed life over an immense
time.
Influences1. Fossil Study- Georges Buffon
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Suggests Earth is much older.
Specific fossils and certain living animals were similar
but not identical. Suggesting- A common ancestor
2. Lamark proposes life evolves or changes.
Evolution is a process of adaptation.
Inheritance of Aquired CharacteristicsLamark incorrectly thought that by using or
not using certain body parts the organism
developed characteristics that could be
passed on to the offspring.
Giraffe example
For this to occur DNA ( genes) have to be
modified.
Adaptations
Adaptation- an inherited characteristic that
improves an organism’s ability to survive
and reproduce in a particular environment.
Examples of adaptations.
3. Darwin’s Voyage
1831- HMS Beagle
Darwin made observations in South America.
Darwin questions his views.
He notices the plants and animals of South
America were distinct from species of Europe.
Species living in South America were descended
from ancestral species on that continent.
Galapagos Islands.
Chain of volcanic islands off the western coast of South
America.-Equador
Darwin notices - species are similar but different from the
plants and animals of the nearby mainland. Each island
had different species from each other.
Darwin infers - species changed and adapted to their new
environments on the islands after they colonized the
islands.
4. Charles Lyell’s - gradual and observable geological
processes that explain physical features of Earth
today.

Examples include erosion and earthquakes .
Conclusion- Earth is much older than previously thought.
Influences on Darwin
5. Malthus essay- Human suffering

human population’s growth rate is faster than
the rate at which food and other resources
can be supplied.
Darwin realized this concept applies to all
species.
6. Alfred Wallace- describes the same idea
of evolutionary change.
The Origin of Species
Darwin publishes his book in 1859.
2 main points1. Descent with Modification- Accounts for
diversity of life
Species on organisms on Earth today
descended from ancestral species.
This spread into various habitats occurred over
millions of years.
In their habitats they accumulated different
modifications or adaptations.
Example: fur color in rabbits.
2. Natural SelectionA process, individuals with inherited
characteristics that are well-suited to the
environment leave more offspring than other
individuals.
Over time this process can cause a change in
the characteristics of a population.
Natural Selection as a cause of evolution
Adaptation is the result of evolution.
Figure 14-9- Example of snails.
Different from selective breeding by farmersoccurs over a shorter time and the farmers do
the selection not the environment.
Evidence for Evolution
Concept 14.2 pp. 299-304
Fossil Record
Fossils are preserved remains -past.
Most fossils -sedimentary rocks; rivers,
lakes,swamps, sea .
Fossil record-chronological collection.
Each rock layer-a particular time period.
Older fossils- bottom.
Prokaryotes-oldest form of life; in rocks
~3.5 billion yrs. old
Terms
extinct species- species that no longer
exists.
Paleontologist- scientist that studies
fossils.
Fossils of ancestral life link the past and
the present.
Geographical Distribution
Patterns explain evolution.
Geographic distribution of organismshow species possibly evolved.
Explains why related species are found
today in a particular geographical area.
Examples- Australia has many pouched
mammals (marsupials) and few
placental animals.
Hypothesis_______________________
________________________________
____.
Homologous structuresDefinition- similar structures in species
that share common ancestor.
Example- forelimbs of mammals have
the same skeletal parts even though
the function of these limbs is completely
different.
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Human arm, cat foreleg, whale flipper, bat
wing.
These structures have become adapted.
Vestigial StructuresDefinition- remnant of a homologous
structure that no longer has a function in
modern related species.
Often vestigial structures -reduced size.
Example- whale vestigial hipbones.

Hypothesis- whales descended from land
dwelling organisms with 4 limbs.
Natural selection favors survival of
individuals with genes for reduced
versions of these structures.
Comparison of Embryonic
Development
Closely related organisms have similar
stages of development.
All vertebrates evolved from a common
ancestor.
 Example- pouches on side of throat.
Fish
gills
Birds and primates
bones of
skull.
Molecular BiologyDNA sequences
Common genetic code shared by all species.
Unrelated individuals-more differences in
DNA sequence.
If 2 species have genes and protein
sequences that match closely- recent
common ancestor .
If 2 species have more differences in DNA
and protein sequences- no close common
ancestor.
Figure 14-16- Humans, chimps, and gorillas
based on Hemoglobin amino acid sequences
are closely related.
Natural Selection
Concept 14.3 pp 305-309
A population- a group of individuals of
the same species living in the same
area at the same time.
Finches on Galapagos Islands
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Individual finches of each island make up a
separate population. Over time, due to
isolation they become isolated and
eventually become separate species.
13 species of fincheskey characteristic- beak- food sources.
VariationDefinition- differences among members of the
same species.
This variation is inherited and passes to
offspring.
Siblings share more traits with each other and
their parents than they do with unrelated
individuals
Individuals with inherited traits best suited to
their environment survive and reproduce
better than less fit individuals.
Figure 14-19.
Artificial Selection
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Selective breeding by humans ( plants and
animals) to produce offspring with
desirable genetic traits. ExamplesGreat change in short time.
Natural Selection- comparison- the
environment does the selecting
Natural Selection- pesticides
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Figure 14-21
The pesticide does not create resistance; it
selects for resistant insects already
present.
Pesticide Resistance
By spraying crops with poisons to kill insect pests, humans have favored the reproduction of
insects with inherited resistance to the poisons over those with no resistance.
Gene Pools
Concept 14.4 pp. 310-316
Gene Pool
Definition- all the alleles of a population.
A population -smallest level of evolution.
Reservoir of genes for natural selection.
Supplies genetic variation.
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Sexual recombination- meiosis and
fertilization contributes to variety.
Mutations & sexual recombination -random
Frequency of alleles -how often certain alleles occur in the gene
pool. Usually expressed as decimal or a percentage,
Changes in Gene Pools
Microevolution- generation to
generation change in the allele
frequency.
2 main factors :
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Genetic drift
Natural selection
Hardy-Weinberg Equilibrium-
Describes populations in which
the gene pool does not change.
 Such populations have constant
allele frequencies; are not
evolving.
 Rare for populations to remain in
H-W equilibrium.
 Serves as a no-change baseline

Genetic Drift
Definition-a change in the gene pool
due to chance.
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The smaller the population the greater the
impact of genetic drift.
Larger populations are more stable.
Reduction in Population Size
Reduces the size of gene pool ;reduces
genetic variation in a population.
2 Big effectsBottleneck Effect- disasters –
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Earthquakes, floods, fires, droughts
Drastically reduce pop. size; new
population has less variation.
May affect a population’s ability to adapt.
Ex.- cheetah pop.
Founder Effect- a few individuals colonize a new
habitat.

Galapagos Island species.
Lesser mechanisms for changing
allele frequencies
1. Gene Flow –
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The exchange of genes with another
population.
Migration of fertile individuals between
populations.
Gene flow reduces genetic differences
between populations and… could result in a
single population.
2. Mutations – change in DNA
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If carried by a gamete- enters the gene pool.
Original source of variation.
Important in asexually reproducing organismsbacteria.
If favorable ; rapid increase due to natural selection
Natural Selection
Not random
Leads to adaptation
Biological Fitness- Contribution to the
gene pool of the next generation of the
most “fit”.
Production of healthy, fertile offspring is
what counts.
Darwin’s Finches
Peter and Rosemary Grant’s Research
30 yr. Study in the Galapagos.
2 species of finches with different beak
sizes.
Their data related beak size to changes
in environment- wet and dry seasons
and types of seeds available.
Data provided evidence for natural
selection occurring in a shorter time
span.
Grant’s research on Darwin’s
Finches.
Evolutionary Biology 14.5
Natural Selection and Sickle Cell Disease.
 Sickle Cell Disease- abnormal shaped rbcs- 2
alleles needed for the disease
 Heterozygous- no disease but immunity to
malaria.
 30% of the African population is heterozygous
in endemic malaria areas.
 Natural selection maintains a higher allele
frequency.
Malaria trophozoites and life
cycle.
Antibiotic Resistance- evolution in
action
Natural selection
Resistant strains of bacteria
 Huge public health issue
Resistant tuberculosis
Resistant HIV
Methicillin resistant
staphylococci.
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Origins of Biological
Diversity
Chapter 15: pp 322-351
Concept 15.1
The origin of new species.
Essential question:
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How do biologists identify species?
How do species arise?
Objectives:
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Explain biological species concept.
Compare microevolution and
macroevolution.
Describe types of reproductive barriers.
Analyze how adaptive radiation contributes
to species diversity.
What is a species?
A distinct form of life.
Biologists use the biological species
concept to define a species as a
population whose members breed with
one another to produce fertile
offspring.
Members of one species do not breed
with members of another species.
This definition- for sexually reproducing
organisms.
How does macroevolution differ from
microevolution?
Microevolution is evolution on the smallest
scale; generation to generation change in the
allele frequencies in a population.
Macroevolution is dramatic changes that are
seen in the fossil record. To explain how we
evolved from simpler life forms. Includes:
 Origin of different species- speciation.
 Extinction of species.
 Evolution of major features
Key concept- new species leads to
biodiversity
Reproductive Barriers:
Reproductive isolation- keeps 2 similar
species from breeding. Due to:
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Timing- different breeding seasons. Skunk
example.
Behavior- different courtship/mating. Ex.
Songs of birds
Habitat- adapted to different habitats- Fish
ex.
Incompatible reproductive structures.
Infertile hybrids- Horse x Donkey
mule.
Geographic Isolation separates
populations leading to new species.
Examples include:
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mountain ranges- range of ecological zones.
Glaciers and isolated islands
Depends on the organisms’ ability to move
about. Examples:deep canyons,wide rivers.
Birds, pollen, coyotes vs. antelope squirrels.
Splinter populations-separation of a small
portion of the population from the main
population.
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Crucial event in origin of a new species.
Genetic drift- chance and Natural selection can
make the splinter population less and less like the
main population.
Do all isolated populations
survive and become new
species?
No , not all isolated populations survive
and become new species.
Speciation only occurs if the two
populations can no longer interbreed
Not all isolated populations survive and
become new species. with each other.
Figure 15.6 model- pg 328.
Adaptive Radiation
Evolution from a common ancestor that
results in diverse species adapted to
different environments.
Transparency- Figure 15-7 pg. 328.
Islands serve as showcase- ex.
Hawaiian islands.
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Physically diverse with differences in
altitude and rainfall .
New lava flow supports adaptive radiation.
Most native species are found nowhere
else.
Tempo of Speciation
Punctuated equilibrium- a model used to
address the observation that species often
diverge in spurts of rapid change, then exist for
long periods of time with little change.
The refining of a scientific theory of gradual
change.
Natural selection and adaptation happen, but
when the species is “young” .
Major changes are less common once the
species is established.
Speciation is rapid in terms of the fossil record.
Most successful species last 1-5 million years.
Figure 15-9
In contrast to a more gradual model of evolution,
punctuated equilibrium suggests that a new species
changes most as it buds from a parent species. There is
little change for the rest of the time the species exists.
Evolution is a
Remodeling Process
Concept 15.2
Refining Existing Adaptations
Examples- eyes, fins, flippers, wing
structures.
What are some functions of eyes in
animals?
How are these useful in owls, moths,fish,
rabbits, worms-planaria, humans?
Key- Natural selection/adaptations needed
in different environments.
Eye types founds in different
mollusks
What are mollusks?
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A diverse group of soft-bodied animals that include
snails, clams, mussels, oysters, octopus, squid.
Invertebrates- lack a backbone.
Characteristics- shell, muscular foot.
50,000-130,000 species- found in trees, gardens,
freshwater ponds,streams, estuaries,beaches,
ocean.
Occurred over several stages of
development.
View OnLine Activity 15.2
Complex structures evolved from simpler
structures.
Figure 15-11
These diagrams show the range of complexity in the structure of eyes
among various species of mollusks living today.
Adapting Existing Structures
Evolved structures fulfill different functions
later on.
Chitin- exoskeleton (shell) of arthropodssegmented invertebrates with jointed legs
(includes insects, spiders, lobsters, etc.)
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Earlier the chitin protected them from predators in
the ocean.
Now, on land the exoskeleton protects them from
dehydration.
Flippers of penguins (birds)- modified wings
used now for swimming. Since penguins
occupy islands where predators are rare,
flight is not as important, but getting food in
the water is.
Embryology
Explains genetic basis for
remodeling.
DefinitionMaster gene controls development.
Mutations can cause some bizarre
effects.
ExamplesRate/timing of some developmental
events
Example- Feet type in salamanders.
Questions:
Does evolution always
progress towards more
complex organisms or
adaptations?
Why or why not?
Examples?
Concept 15.3- Fossil Record
How Fossils Form:
 Types of fossilsGeological Time Scale:
 Earth’s history
 4 distinct eras (ages)
 Further subdivisions
 Boundaries-
Fossil Dating:
 Relative dating Actual age- radiometric dating
Uranium-238
Carbon dating
Continental Drift/ Plate movements:
 Affects climates
 Geographical isolation
 Similar species in different locations
 Major eventsFormation of Pangaea
Breakup of Pangaea
Mass Extinctions:
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Great species loss
Examples65mya. Extinction of dinosaurs Theories245mya.-90% loss of marine
animals.
AffectsNegative
Positive
Taxonomy
Concept 15.4 pp. 341-349
Taxonomy
DefinitionContinuous processGoals:
 A universal scientific name for
each species
Why is this necessary?
 Organize species into larger
groups.
Two main systems Older Linnaean system
 Modern cladistics
Classification
Carolus Linnaeus
Binomial Latin name
 First part- genus name
 Second part- species name
 Example- leopard
An ordering of species into broader
and broader groups.
 species-genus-family-order-classphylum-kingdom
 Figure 15-24 in textbook.
 Leopard example
Figure 15-24
The leopard shares many characteristics with the lion—which belongs to the same genus—but far fewer characteristics with snails, sponges, or
earthworms, though they are all members of the animal kingdom.
Evolutionary relationships among
species
Phylogenetic tree “evolutionary history”
 branching pattern
Shows common ancestors
Figure 15-25
Phylogenetic Tree
In a phylogenetic tree, each branch point represents a
common ancestor of the species above that point.
Classification based on
homologous
structures:
Homologous
structure definitionExampleEvolved from single structure in a
common ancestor
The more homologous structures;
the more closely related the species.
Homologous- structural parts match
up.
Convergent evolution
Definition-.
 Unrelated species from similar
environments have similar
adaptations.
 Analogous structures-.
example- wings of birds and
insects.
similar adaptations.
entirely different structures.
evolved independently.
no shared common ancestor.
Molecular data to classify
Comparing DNA/ protein sequences
Research- genome
Computer technology
Used to backup fossil data
Branching pattern
Figure 15-28
Wolves and cats diverges early on
Cats and leopards diverged later.
Identifying Clades
What is a clade?
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An evolutionary branch in a phylogenetic
tree.
Each clade consists of the ancestral
species and all of its descendants.
Figure 15-29. Identify the clades and
associated species.
All organisms in a clade share homologous
structures.- derived characters.
What is a cladogram?

Figure 15-30.
Figure 15-29
Each shaded area in the
phylogenetic tree
highlights one clade,
such as the yellow area
including species B
through H.
Figure 15-30
This cladogram shows how derived characters can be used to identify clades among certain vertebrates (animals with
backbones). All the species shown here share a common ancestor that had a backbone. (Each clade is actually defined by
several derived characters, not just one.)
5 Kingdom scheme vs 3 Domain
System
5 kingdoms- Monerans-bacteria
Protists
Plants
Fungi
Animals
3 Domains
 Bacteria
 Archaea
 Eukaryotes