Transcript Evolution - IB BiologyMr. Van Roekel Salem High School

EVOLUTION
IB BIO II
Van Roekel
4/14/14
BILL
• What are some examples of evolution you know of? Outline how/why
that evolution took place.
• Example: Peppered moths – during industrial revolution, soot covered
the trees, so a species of moths that were once peppered colored
became black to blend in to their environment.
Darwin’s Theory of Evolution
• Charles Darwin traveled around the world on
HMS Beagle for five years making various
observations.
• In 1859 Published On the Origin of Species
• Came up with the Theory of Evolution by
Natural Selection
• Evolution: the process of cumulative change in
the heritable characteristics of a population
Evidence for Evolution
• Fossil Record: by observing fossils one can
conclude that life on Earth is Constantly changing
and these changes occur over hundreds of
thousands or millions of years.
• Artificial Selection: Small changes over time in
domesticated animals by breeders to produce
animals with the most desirable characteristics
• Homologous Structures: Similar structures with
different functions provide evidence of common
ancestors.
Homologous Structures
Structural Evidence con’t.
• Vestigial organs
• Organs of many animals
are so reduced in size
that they are just
vestiges, or traces, of
homologous organs in
other species
• These do not affect an
organism’s ability to
survive and reproduce
Embryonic Similarities
• Early stages, or embryos, of animals with a backbone are
very similar
• Same groups of embryonic cells develop in the same
order and pattern to produce the tissues and organs of all
vertebrates
Embryos
Mechanism of Evolution
• Overproduction of offspring
• Most organisms produce far more offspring than
could survive
• Creates competition for resources in
populations (struggle for survival)
• Competition leads to adaptive behaviors to
gain/use more resources.
• Leads to variation within species and
populations
• Variations can provide individuals with
advantage or disadvantage for survival
Causes of variety in offspring
• Mutations in DNA can lead to harmful or
beneficial changes in organisms phenotype
• In Each generation only a few genes mutate and most
have little affect on phenotype
• Sexual reproduction is more powerful source of
variation through meiosis and fertilization
• Meiosis: Random distribution of chromosomes results in
each egg and sperm having different combinations from
others
• Fertilization: Combination of different genes from sperm
and egg cell and only one sperm cell can fertilize one
egg cell. Leads to variation in offspring
Natural Selection
• Natural selection determines which individuals
survive and which do not based on their
environment and the compatibility of
characteristics to survive.
• AKA Survival of the fittest
• Fitness: an individual’s ability to survive and
reproduce in a given environment
Process of Natural Selection
• Individuals w/in population overproduce offspring,
which have natural variation due to genetic
differences
• Individuals with poorly adapted characteristics are
less successful at gathering resources and have
lower chance of survival
• Individuals with well adapted characteristics are
more successful at gathering resources and have a
higher chance of survival
• Individuals that survive have a better chance at
reproducing and passing on their genetic traits
• Over many generations the accumulations of
genetic characteristics in a population results in
evolution
Examples: Antibiotic Resistance Bacteria
• Antibiotics are medicines that kill or inhibit growth
of bacteria
• Some bacteria can develop resistance to
medicine
• Occurs when an individual take a course of
antibiotics and not all of strain is destroyed
• Remaining bacteria multiply and more are
resistant to antibiotics
• Occurs because of mutations, or plasmid transfer
(one bacteria donates genetic information to
another)
BILL
• Evolution is caused by Natural Selection. Outline the process
of natural selection.
• Individuals w/in population overproduce offspring, which
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have natural variation due to genetic differences
Individuals with poorly adapted characteristics are less
successful at gathering resources and have lower chance of
survival
Individuals with well adapted characteristics are more
successful at gathering resources and have a higher chance
of survival
Individuals that survive have a better chance at reproducing
and passing on their genetic traits
Over many generations the accumulations of genetic
characteristics in a population results in evolution
Assessment Statements
• D.1 Origins of Life on Earth
• D.1.1 Describe the process needed for the spontaneous origin of life
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on Earth
D.1.2 Outline the experiments of Miller and Urey into the origin of
organic compounds
D.1.3 State that comets may have delivered organic compound to
Earth
D.1.4 Discuss possible locations where conditions would have
allowed the synthesis of organic compounds
D.1.5 Outline two properties of RNA that would have allowed it to
play a role in the origin of life
D.1.6 State that living cells may have been preceded by protobionts,
with an internal chemical environment different from their
surroundings
D.1.7 Outline the contribution of prokaryotes to the creation of an
oxygen-rich atmosphere
D.1.8 Discuss the endosymbiotic theory for the origin of eukaryotes
Problems for Starting Life
1. Life is based on organic molecules, such as amino
acids.
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Early Earth only had inorganic matter, so either these materials
somehow combined to form organic molecules, or they were
extra-terrestrial
2. Organisms must be organized
1. Organic molecules must become polymers, larger molecules
necessary for life such as polypeptides (proteins)
3. Living things must reproduce
1. Needed self-replicating molecules (RNA is needed to form DNA)
4. Water dissolves molecules
1. Living organisms needed to form membranes to separate
internal and external environments
Miller and Urey
• Simulated Earth’s believe atmosphere in a lab to see if
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they could recreate formation of organic molecules by
chemical evolution
Introduced gases believed to be present at the time
(methane, hydrogen, ammonia, water vapor, etc)
Heated and cooled water to recreate water cycle
Heated water (simulate volcanic activity)
Sparked electricity (lightning)
Exposed “atmosphere” to UV radiation (sun)
Miller and Urey Results
• Organic compounds formed!
• 13 of naturally occurring 20
amino acids were found
• Some sugars and nucleic
acids
• Does not represent life, but
now have building blocks of
life and know they can be
formed from inorganic
material
Comets Delivery
• Panspermia: idea that life originated on Earth from
materials delivered on a comet in the form of amino acids,
or bacteria
• Late Heavy Bombardment: shower of comets 4 billion
years ago
• Existing bacteria and archaebacteria have been found in
odd and extreme environments, making it feasible that
they could survive on comets in space.
Synthesis of Organic Compounds
• Several Hypotheses about where synthesis of organic
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compounds could have taken place, including:
Space
Volcanoes
Deep Ocean
Intertidal zones with alternating wet/dry environments
Synthesis of Organic Material
• Space
• Astronomers claim to have found glycine (simple amino
acid) in space
• Cosmic radiation could provide energy necessary for
formation of complex compounds
• Materials from Mars could have been thrown into space
from comets
• Does not prove life originated in space, just that it can
travel through it
Synthesis of Organic Compounds
• Volcanoes
• Eruptions release water vapor and other gases and
minerals into atmosphere, which could be used to create
organic compounds
• Rich source of materials and warm environment are
favorable in formation of amino acids
Synthesis of Organic Compounds
• Deep Ocean
• Hydrothermal vents in deep ocean release hot water from
beneath ocean floor
• Hot water rises from earth’s crust, carrying minerals along
the way
• Hot bed for strange and ancient creatures, supporting
idea of early life
• http://exploringorigins.org/fattyacids.html
Synthesis of Organic Compounds
• Alternating Wet/Dry Zones
• Intertidal zones or flood plains have drying clay particles
that could have created catalyzing reactions
• When clay dries out and is heated, up to 200 amino acids
can spontaneously join as polypeptide chain.
• Stromatolites, one of earth’s oldest life forms, live in
intertidal zones.
• Suggests conditions that were favorable for early life
Early Reproduction
• Most organisms today pass genetic info using DNA and
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enzymes to replicate DNA
PROBLEM!!
Prebiotic Earth had no enzymes, meaning DNA unlikely
hereditary source
What is a likely source that can store, transmit, and
replicate genetic information?
RNA
Early Reproduction
• RNA, however, can replicate without the use of enzymes
in some situations.
• RNA acts as a catalyst (enzyme) helping certain chemical
reactions occur, such as formation of peptide bonds,
polymerization of nucleotides
• RNA acting as an enzyme is called ribozyme
• Believe to be genetic material in early earth.
Bill - Review Questions
• Outline the Role of clay molecules in the possibility of
creating organic compounds
• What is the theory of panspermia
• Outline the experiments of Miller and Urey in the origin of
organic compounds.
Review Answers
• Organic Molecules Stick to the clay, which can then act as
a catalyst causing organic molecules to be brought
together
• Panspermia is the theory of the origin of species by the
arrival of organic compounds from space.
• Simulated the conditions of pre-biotic earth in a sealed
apparatus. They used gases such as methane, ammonia,
water vapor, and hydrogen. Then using boiling water to
simulate temperature, electricity to simulate lightning, and
uv radiation to simulate the sun, they recreated the
conditions of earth to see if organic compounds could
form from inorganic compounds. Found organic
compounds such as amino acids, sugar, and nucleic
acids.
Protobionts
• Protobionts: evolutionary precursors to prokaryotic cells
• Proteinoid: microsphere, tiny bubble of polypeptide
chains that surrounded polymers, establishing and
maintaining different internal environments from the
external
• Coacervate: microscopic sphere formed from lipids that
formed spontaneously due to hydrophobic forces. Also
maintain separate internal environment and are
selectively permeable
Protobionts
• Protobionts served the purpose of separating internal
environments from external, to protect polynucleotides
such as RNA, and allow different chemical reactions to
take place
• Over time true cell membranes evolved and other cellular
abilities such as respiration and reproduction were
developed
Oxygen Production
• Remember, no oxygen was present in prebiotic earth,
meaning earliest life forms were anaerobic
• Anaerobes consumed food, increased in population, and
eventually food ran scarce
• Some bacteria developed a form a chlorophyll allowing
the ability to perform photosynthesis and began producing
oxygen (about 3.5 billion years ago)
Importance of Oxygen
• Oxygen is toxic to anaerobes, so many were destroyed
• Broke down chemicals in atmosphere to carbon dioxide
and oxidized certain sediments
• Formed ozone layer, blocking harmful UV radiation
Endosymbiotic Theory
• States that organelles found inside modern cells were
once independent prokaryotic cells that were engulfed by
a bigger cell. Rather than being digested, they formed a
mutualistic relationship with the host
• Supported by the fact that Mitochondria and Chloroplast :
• have double membrane
• Have own circular DNA (similar to prokaryotes)
• Can perform protein synthesis using small ribosomes (prokaryotes)
• Can make copies of themselves when more are needed by binary
fission
Review Questions
• State the name of one organic monomer and one organic
polymer on prebiotic Earth
• Describe one hypothesis of how prebiotic polymers solved
the problem of depolymerization
• Explain why UV radiation levels were higher in the
atmosphere of early Earth than they are today.
• Outline the theory of Endosymbiosis.
Answers
• State the name of one organic monomer and one organic
polymer on prebiotic Earth
• Monomers could be amino acids, simple sugars, or
nucleotides
• Polymers could include polypeptide chains,
polysaccharides, or RNA
Answers
• Describe one hypothesis of how prebiotic polymers solved
the problem of depolymerization
• Surrounds themselves with proetinoid microspheres or
coacervates that would protect them from the external
environments
Answers
• Explain why UV radiation levels were higher in the
atmosphere of early Earth than they are today.
• There was no oxygen present in early earth and
consequently, no ozone layer. After oxygen began to be
produced by organisms that performed photosynthesis,
the formation of the ozone layer began.
Answers
• Outline the theory of Endosymbiosis.
• A bacteria cell engulfed another bacterial cell but instead
of digesting it, they formed a mutualistic relationship. The
smaller cell provided energy to both cells and the larger
cell provided protection to the smaller cell.
SPECIES & SPECIATION
4/7/14
Assessment Statements
• D.2.1 Define allele frequency and gene pool
• D.2.2 State that evolution involves a change in allele frequency
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in a population’s gene pool over a number of generations
D.2.3 Discuss the term species
D.2.4 Describe three examples of barriers between gene pools
D.2.5 Explain how polyploidy can contribute to speciation
D.2.6 Compare Allopatric and sympatric speciation
D.2.7 Outline the process of adaptive radiation
D.2.8 Compare Convergent and divergent evolution
D.2.9 Discuss ideas of the pace of evolution, including
gradualism and punctuated equilibirium
D.2.10 Describe one example of transient polymorphism
D.2.11 Describe sickle cell anemia as an example of balanced
polymorphism
Gene Pools
• Gene Pool: all the genetic information present in
the reproducing members of a population at a
given time.
• Large gene pools in populations with substantial
variety in traits
• Small gene pool in populations with little
variation, most notably in cases of inbreeding
Allele Frequency
• Allele Frequency measures the proportion of a
specific variation of a trait in a population, or the
chance a chromosome carries that specific allele
• i.e 25% of fruit flies have an allele for white eyes
• Does not mean that that many members of the
population have the allele, just that it is present
on one of the chromosomes
• What is the allele frequency of A and a in population 1 & 2
• ¾ A & ¼ a in population 1
¾ A & ¼ a in population 2
• How many individuals express the trait coded for by the
allele a in population 1 & 2?
• O in population 1 and 2 in population 2
Evolution and Alleles
• Gene pools are relatively stable over time, however, when
changes occur, evolution is seen
• New combinations of alleles lead to new phenotypes, that
can then be selected for or against by the environment
• Alleles that are advantageous to a populations survival
will be passed on and have a higher frequency in later
generations
• Alleles that are disadvantageous will not be passes on
and have a lower frequency in later generations
Evolution and Alleles
• Immigrations and
emigrations will also have
an effect on allele
frequencies
• For whatever reason, when
a gene pool in modified,
some degree of evolution
has occurred.
BILL
• What are gene pools? How can you tell evolution
occurred by looking at gene pools? What would cause a
change in the gene pool of a species/population?
• Gene pools are all of the genetic information present in
the reproducing members of a population at a given time.
• If there is a change in allele frequency (the amount of
alleles in a gene pool) then some type of evolution has
occurred.
• Alleles that are advantageous to a populations survival
will be passed on and have a higher frequency in later
generations
• Alleles that are disadvantageous will not be passes on
and have a lower frequency in later generations
Species
• Species is the basic unit for classifying organisms
which included organisms that:
• Have similar physiological and morphological
characteristics which can be observed and
measured
• Have the ability to interbreed and produce fertile
offspring
• Genetically distinct from other species
• Have common phylogeny
Barriers between Gene Pools
• Occasionally, there are barriers between
populations of the same species
• Barriers can be:
• Geographical Isolation
• Temporal Isolation
• Behavioral Isolation
• Hybridization
Geographical Isolation
• Physical barriers such as land or water prevent
males and females from find each other and
breeding
• Rivers
• Mountains
• Clearing a forest
Temporal Isolation
• Incompatible time frames which prevent the
populations or gametes from encountering each
other
• Female parts of flowers of one population
mature at a different time from the release of
pollen on another population
• One population is still hibernating or has not
returned from migrations when another
population is ready to mate
Behavioral Isolation
• Population’s lifestyle and habits are not
compatible with those of another population
• Birds rely on courtship displays in order for one
sex to mate with the other, if displays of one
population are different from another, they will
not consider each other for mating
• Hybrids are infertile, so difficult to continue
population on their own.
What about Horses and Donkeys?
• When they mate, they produce an offspring called a mule.
Why aren’t they the same species?
• Both parents are equines (of the same family) so they are
related but are not the same species. They do not posses
the same number of chromosomes which is one of the
reasons the offspring are infertile.
Questions
• Compare and Contrast Geographical and
Temporal Isolation
• Both are examples of barriers to gene pools but
geographical isolation is a physical barrier such as a
mountain or a river whereas temporal isolation is a
problem in the synchronization of time when
populations try to connect.
• Explain why a zebroid (combination of a zebra
and a horse) is not considered a new species.
• Because like most hybrids, it is considered
infertile and cannot produce offspring.
Speciation
• The process of an evolving population changing
significantly enough so that the production of
offspring with the original population is no longer
possible
• Two types of speciation:
• Allopatric
• Sympatric
Allopatric Speciation
• Occurs when a new species forms because it is
physically separated from an existing species.
• Gene flow is cut off between these two
populations, causing different evolutionary
directions
• Once populations have been separated into 2
gene pools they can diverge through natural
selection or through random genetic drift.
• http://www.mhhe.com/bi
osci/esp/2001_gbio/fold
er_structure/ev/m3/s2/ev
m3s2_4.htm
Sympatric Speciation
• When a new species forms from an existing
species while living in the same geographical
area
• Temporal and behavioral isolations could produce
a new species
Speciation Activity
• You will simulate the process of speciation in a specific
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environment
You will work in groups of 3 and will be isolated on a
island that has a specific climate
You must select and write down all the phenotypic
characteristics that exist in your group to improve your
group’s survival on the island.
Answer the questions on the activity on a separate piece
of paper (1 per group)
Draw individual on poster paper
Compare your species to classmates species and answer
questions
Polyploidy
• Polyploidy refers to individuals or populations
with three or more sets of chromosomes
• 3n = triploid
• 4n = tetraploid
• 5n = pentaploid
• Occurs when cell division does not completely
separate copies of chromosomes
Polyploidy
• Having multiple sets of chromosomes makes
errors more likely to occur during replication.
• Makes polyploidy individuals great source of
speciation
• Much more common in plants, which results in
more vigorous plants that produce bigger fruits or
are more resistant to diseases
Adaptive Radiation
• Occurs when many similar but distinct species
evolve relatively rapidly from a single or small
number of species
• Results in phenotypic (morphological and
physiological) adaptations that allow organisms to
exploit a different niche in environment
• Examples:
• Lemurs
• Darwin’s Finches (again)
Adaptive Radiation
• Lemurs
• Found in Madagascar and Comoro Islands
• No competition from apes or monkeys so able to
proliferate freely, which led to variation and
diversity
• Some adapted for living on ground, others in
trees, some live in rainforests, others in deserts,
some are nocturnal some are diurnal (day active)
Convergent and Divergent Evolution
• What do humans, octopi, and box jelly fish
all have in common?
• All have complex camera eyes. These traits
evolved independently in organisms that
are very distantly related. This is an
example of convergent evolution
Convergent and Divergent Evolution
• Convergent Evolution
describes the acquisition of the
same biological traits in
unrelated lineages
• Penguins in southern hemisphere
and Auks in Northern hemisphere
both have wings as flippers
• Flight in birds, bats, insects and
flying fish
• Features that come about as a
results of convergent evolution
are analogous structures
Convergent and Divergent Evolution
• Divergent Evolution is
when two organisms
become phenotypically
different from a common
ancestor because of
natural selection
• Features that arise from
divergent evolution are
called homologous
structures. These
features either look
different or have a
different purpose in
each species.
Gradualism and Punctuated Equilibrium
• Evolutionary biologist believe that pace of
evolution may be one of two main ideas:
• Gradualism: changes are small, continuous, and
slow
• Punctuated Equilibrium: changes are relatively
quick and followed by long periods of little or no
change
Gradualism
• Supporters argue that the fossil record shows a
succession of small changes in phenotypes of
species indicating the process of speciation is a
steady, constant process with transitional stages
between major changes.
Punctuated Equilibrium
• Speciation happen quickly, in a response to the
environment, i.e. a volcanic eruption that destroys
some species. Others then adapt, exploiting new
niches made available. The rest of the time,
species live for millions of years with little or no
change
Problems
• Only Evidence available is fossil record
• Could be incomplete and missing links are not
known
• Some characteristics, such as pigmentation,
behavior, or mating calls are not fossilized
• Just because fossilized structures look similar to
modern organisms does not guarantee they are
direct descendants
BILL
• Compare and contrast allopatric speciation and sympatric speciation;
convergent and divergent evolution; gradualism and punctuated
equilibrium
• Allopatric speciation occurs when two gene pools are completely cut off
from each other by a physical barrier, whereas sympatric speciation
occurs when a new species forms from an existing species while living in
the same geographical area, most likely because of temporal or
behavioral isolation.
• Convergent evolution describes the acquisition of the same biological
traits in unrelated lineages and results in analogous structures between
unrelated species. Divergent Evolution is when two organisms become
phenotypically different from a common ancestor because of natural
selection and results in homologous structures between different species.
• Gradualism is the idea that evolution occurs very slowly by small,
continuous changes over a long period of time. Punctuated equilibrium
is the idea that evolutionary changes are relatively quick and stimulated
by some sort of environmental event, which is then followed by long
periods of little or no change
Polymorphism
• Different versions of a species are referred to as
polymorphisms (many shapes) and are typically
a result of mutations
• Results in more than one common form of a
population
• Transient Polymorphism occurs when the
versions change to best fit the environment and
these changes can be temporary
• Balanced Polymorphism when two or ore
alleles within a population are not changing but
are stabilized by natural selection
Transient Polymorphism
• Peppered moths have a peppered (grey) and
melanic (black) form
• During industrial revolution, melanic form was
more prevalent because it provided better
camouflage than the grey ones. Called Industrial
Melanism.
• Today, because of clean air act and reduced air
pollution the population has higher number of
peppered moths
Transient Polymorphism & Natural Selection
• In the case of peppered moths, it is natural
selection through predation by birds
• Phenotypes are fit or unfit depending on
environment
• Black moths more fit when trees covered with
soot
• Peppered moths more fit when trees are clean
• Survival of fittest
Balance Polymorphism & Sickle Cell Anemia
• Sickle cell anemia can be debilitating, but is also
very resistant to malaria.
• Malaria is an infectious disease that occurs in
tropical regions where a parasite (Plasmodium) is
transmitted to human blood by infected mosquitos
• Parasite attacks red blood cells and causes fever,
chills, and possibly death
Balanced Polymorphism & Sickle Cell Anemia
• Polymorphism versions:
• Normal RBC (HbAHbA): highly
susceptible to Malaria
• Sickle Cell Trait (HbAHbS):
resistant to Malaria due to
chemical imbalances (lack of
potassium kills Plasmodium), and
in most cases are not anemic
• Sickle Cell Anemia (HbSHbs):
highly resistant to Malaria, but
can be fatal because of curved
RBCs and anemia
Balanced Polymorphism & Sickle Cell Anemia
• Allele frequency of HbS (sickle cell) is stable and
shows balanced polymorphism because of two
pressures of natural selection
• Selected against because it can be lethally debilitating
• Selected for because it is resistant to malaria
• It can be selected for or against, so balance is
reached by heterozygotes, who are more fit to
survive in zones plagued by malaria.
Review Questions
• Outline the conclusions that Miller and Urey Drew from
their experiments. (2 marks)
• Discuss the possible roles of RNA in the origin of life on
prebiotic earth. (4 marks)
• Explain the process of speciation (5 marks)
• A man with sickle cell trait is climbing the mountains of
Zaire. He has much more difficulty breathing than his
fellow climbers. With reference to his genotype and
phenotype, explain the reason for this difficulty. (3 marks)
Answers
• Outline the conclusions that Miller and Urey Drew from
their experiments. (2 marks)
• Organic compounds were formed from inorganic compounds if the
conditions on pre-biotic earth were right. This means that organic
compounds could have existed on pre-biotic earth and life may
have arisen from non-living conditions.
• Discuss the possible roles of RNA in the origin of life on
prebiotic earth. (4 marks)
• RNA was thought to be the first genetic material on earth because it
can self-replicate. RNA can act as an enzyme called ribozyme,
which has catalytic properties. It can catalyze the formation of RNA
by binding amino acids to form polypeptide chains, and it can also
be transcribed into DNA using reverse transcriptase.
Answers
• Explain the process of speciation (5 marks)
• Process by which one or more species arise from a previous existing
population. This occurs as different populations become isolated.
Populations can be geographically isolated by physical barriers such
as rivers and mountains, or behaviorally isolated by different
courtships or habitat preferences. Isolation results in two separate
gene pools that will become genetically isolated because of natural
selection, which acts independently on the two separated populations.
After prolonged isolation, the two species will not be able to interbreed
and speciation has occurred.
• Sickle Cell Trait Difficulty (3 marks)
• The man has sickle cell trait, so he is a heterozygote, HbAHbS, which
means he has some normal red blood cells and some sickle shaped
blood cells which are inefficient for carrying oxygen. Therefore he
needs to take larger quantities of air and has more difficulty breathing
than others to supply sufficient quantities of oxygen to his cells.