UTSG
BIO120H1
FINAL EXAM
STUDY GUIDELecture 1
Saturday, October 3, 2015
3:20 PM
Key Things To Know
Dobzhansky
Dobzhansky began analyzing the
... [Show More] genes of wild fruit flies, traveling from Canada to Mexico to catch
members of the species Drosophila pseudoobscura. He found that different populations of D.
pseudoobscura did not have identical sets of genes. Each population of fruit flies he studied bore
distinctive markers in its chromosomes that distinguished it from other populations. Dobzhansky
helped discover that different fruit fly populations have different frequencies of two different
versions of the same chromosome; chromosome A might be more frequent in one population
while chromosome A' is more frequent in a neighboring population. If there was no standard set
of genes that distinguished a species, what kept species distinct from each other? The answer,
Dobzhansky correctly realized, was sex. A species is simply a group of animals or plants that
reproduces primarily among themselves. Two animals belonging to different species are unlikely
to mate, and even if they do, they will rarely produce viable hybrids. Dobzhansky ran experiments
on fruit flies that demonstrated that this incompatibility is caused by specific genes carried by one
species that clash with the genes from another species.If the members of a population of flies
should breed among themselves more than with other members of the species, their genetic
profile would diverge. New mutations would arise in the isolated population, and natural selection
might help them to spread until all the flies carried them. But because these isolated flies were
only breeding within their own population, the mutations could not spread to the rest of the
species. The isolated population of flies would become more and more genetically distinct. Some
of their new genes would turn out to be incompatible with the genes of flies from outside their
own population.
Darwin's Theory of Evolution - The Premise Darwin's Theory of Evolution is the widely held
notion that all life is related and has descended from a common ancestor: the birds and the
bananas, the fishes and the flowers -- all related. Darwin's general theory presumes the
development of life from non-life and stresses a purely naturalistic (undirected) "descent with
modification". That is, complex creatures evolve from more simplistic ancestors naturally over
time. In a nutshell, as random genetic mutations occur within an organism's genetic code, the
beneficial mutations are preserved because they aid survival -- a process known as "natural
selection." These beneficial mutations are passed on to the next generation. Over time,
beneficial mutations accumulate and the result is an entirely different organism (not just a
variation of the original, but an entirely different creature
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find more resources at oneclass.com Evolutionary History (macroevolution) – Determining the evolutionary relationships of
organisms in terms of common ancestry – phLJlogeŶetiĐs. Hoǁ the past has shaped todaLJ͛s
world. It involves affinities of organisms like taxonomy and systemic. Comparative data from
biogeography, paleontology, morphology and development are used.
Evolutionary Mechanisms (microevolution) – Determining the ecological and genetic
mechanisms responsible for evolutionary change. It involves population-level studies of natural
selection, adaptation and speciation using diverse organisms.
Founder Events
1. An initially large population
2. A small group of individuals leave the large population and colonize a new area that is geographically
or physically separated from the original population.
3. Due to chance alone - or to Genetic Drift - the genetic composition of the small colony differs from
the large population.
4. Because of these genetic differences, the two populations are reproductively isolated when they
come back into contact with one another. (Chance and genetic drift really are unlikely to be powerful
enough to cause reproductive isolation.)
Founder Events can Dramatically Change Gene Frequencies:
Consider a founder event of two individuals (or one gravid female)
•A ŵadžiŵuŵ of 4 alleles/loĐus aƌe tƌaŶsŵitted
•Most ƌaƌe alleles ǁill ďe lost
•AŶ oĐĐasioŶal ƌaƌe allele ǁill ŵake it thƌough
•“taŶdaƌd theoƌLJ suggests fouŶdeƌ eǀeŶts should ďe ƌelatiǀely unimportant The rare allele will have a
frequency of 0.25
Founder Flush Speciation
Mayr and Carson suggested there was more to the theory
•TheLJ had a ͞WƌightiaŶ͟ ǀieǁ of geŶetiĐs
•Postulated that ƌaŶdoŵ ĐhaŶges iŶ geŶe fƌeƋueŶĐLJ ĐhaŶged the geŶetiĐ environment
•Postulated that a peƌiod of ƌeladžed seleĐtioŶ ;the ͞flush phase͟Ϳ alloǁed edžteŶsiǀe ƌeĐoŵďiŶatioŶ
•The fouŶdeƌ/flush pƌoĐess Đould lead to a geŶetiĐ ƌeǀolutioŶ.
•The geŶetiĐ ƌeǀolutioŶ ǁould ďe the Đause of speĐiatioŶ.
The Founder Flush process
1. An initially large population
2. A small group of individuals leave the large population and colonize a new area that is geographically
or physically separated from the original population.
3. Due to chance alone - or to Genetic Drift - the genetic composition of the small colony differs from
the large population.
4. During the flush phase recombination and relaxed selection allows the formation of a new adaptive
gene complex
5. Because of these genetic differences, the two populations are reproductively isolated when they
come back into contact with one another.
Approaches and Assumptions in Evolutionary Biology
There are four different approaches: observational, theoretical, comparative, experimental.
Biodiversity and Adaptation
Both are products of evolution. The latter is either a state or a process; any trait that contributes to
fitness or the evolutionary process that leads to the origin and maintenance of traits. The former refers
to the variety of life on earth.
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find more resources at oneclass.comClonal Propagation
Asexual reproduction in plants for example, water hyacinth.
Bird Pollination
Aids sexual reproduction in plants. For example, the mouse-tailed plant found in deserts. Many birds
and plants are adapted to conduct this form of pollination.
Perch Function
A protruding stick-like part of a plant designed to provide a platform for the bird to land on in order to
reach into the plant.
Reproductive Success
Passing on of genes in a way that allows the offspring to also pass on the same genes to their future
offspring.
Lecture 2
Saturday, October 3, 2015
4:03 PM
Lamarck
He came up with a linear rather than a branching view of evolution and went further to suggest a causal
mechanism which was the inheritance of acquired characteristics. According to Lamarck, if a giraffe stretched its
neck for leaves, a nervous fluid would make its neck longer and this trait would pass on to its offspring. This meant
that organs or features which an organism did not find useful would disappear or shrink.
Lamarck was wrong since somatic (body) cells have no function in inheritance which is mostly and only governed
by the gametes.
Weismann
He pƌoposed the ͚geƌŵ-plasŵ͛ theoƌLJ of heƌeditLJ statiŶg that aŶd oƌgaŶisŵ has tǁo kiŶds of Đells. These tǁo Đells
did not exchange information – variation originated from the germ cells. He rejected LaŵaƌĐkiaŶ ͚aĐƋuiƌed
ĐhaƌaĐteƌistiĐs͛
Wallace
He co-discovered the chief mechanism of evolution i.e. natural selection alongside Darwin. It occurred to him that
animals and plants experience population pressures i.e. organisms cannot reproduce to their full potential. Many
die before they become adults. He was in close correspondence with Darwin and even wrote him a letter.
Lyell
He wanted to find a way to make geology a true science. He argued that gradual changes had produced the
featuƌes of the Eaƌth͛s surface and found evidence for many rises and falls of sea level. He came up with
͚uŶifoƌŵitaƌiaŶisŵ͛ aŶd fieƌĐelLJ iŶsisted that the pƌoĐesses that alter the Earth are uniform through time. His
contributions allowed Darwin to decipher the history of the Canary Islands.
Malthus
His work in economics influenced the idea of population pressures.
Inheritance of acquired characteristics (See Lamarck)
Germ plasm theory (See Weismann)
Gradualism
Descent with modification (adaptation)
Natural Selection
Requirements for Evolution
Reproduction, variation, and selective pressure.
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find more resources at oneclass.comLecture 3
Saturday, October 3, 2015
5:40 PM
Grant Research
TheLJ ǁoƌked oŶ DaƌǁiŶ͛s fiŶĐhes shoǁiŶg that Ŷatuƌal seleĐtioŶ ĐaŶ soŵetiŵes ďe ǀeƌLJ stƌoŶg aŶd
when it is, evolutionary change can occur rapidly. It has also shown that if you study a system long
enough, you can make new discoveries. They documented the origin of a new specie; a speciation event.
This did not agree with current data about speciation.
Conducted the lost study of NS of beaks. Finches had different shaped beaks. Showed that beaks were
diverging.
Janzen
Tropical ecologist, mark-recapture studies to see how far large bees travelled pollinating trees of the
same species. Trap line foraging. Asked if the distribution of seedlings under a tree had anything to do
with levels of fertility. Found that seeds that fell had low survival probability underneath the maternal
parent since the pests on the tree have adapted to the defenses of the tree. And it is a waste competing
with their offspring. Famous for coevolution/mutualism in ant-acacia of the pea family. These had
thorns which had ants. The ants got benefits from the tree and vice versa.
Tropical vs. Temperate Ecosystems
Tropical – large number of species with great distances; trees are evergreen but wind pollination is
tough in these forests, high diversity, animal population, dense canopies
Temperature, diversity. Differences have an impact on pest pressure on plants.
Biotic vs. Abiotic Factors
Biotic – interactions between organisms which may or may not result in coevolution or mutualism
Abiotic – physical factors; ice, wind. Dominate in places like Chile.
Animal Pollination
Showy bracts; butterflies. Control and Experimental group comparisons.
Mutualism
Co-evolution. Two species exist while relying one each other. Ant-plant mutualism.
Pest Pressure
Plant Herbivory
Field Experiments
Epiphytes
Plants that grow on other plants; not parasitic. Use trees as substrates; aerial roots. There are many
different forms in different families; convergent evolution.
Convergent Evolution
Long-distance dispersal
Adaptive Radiation
Gives us so much biodiversity. It is a process of speciation. Evolution of phenotypical within a rapidly
multiplying lineage as a result of speciation. From a single common ancestor, we radiate many different
species. Identified by four features: (1) has to be evidence of common ancestry, (2)cottelation between
phenotypic function and environment, (3)rapid speĐiatioŶ. Most faŵous of DaƌǁiŶ͛s fiŶĐhes; he ŵade a
mistake by mixing them up.
Flightless Birds
Same specie which flew in other places and whose ancestors flew have lost their ability to fly.
Flightlessness is very common on islands. This evolved as a trait because flying is exhaustive.
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find more resources at oneclass.comSexual Dimorphism
Males and female look and behave differently. In birds, males are flashy and show off. The marine bird
on the Galapagos Island.
Endemism
Geographical Isolation
Darwin realized this when he found marine fossils on the mountains.
Galapagos Islands
A common ancestor split on these islands and adapt allowing exploitation of habitats and resources
Volcanic Islands; 15. Very Old. Their flora and fauna got there by long-distance dispersal – biogeography
DistiŶĐt ǀaƌiatioŶ; eaĐh islaŶd had a diffeƌeŶt speĐies. EŶoƌŵouslLJ iŶflueŶtial foƌ DaƌǁiŶ͛s theoƌLJ of
evolution. Prickly pear cactus; colonized volcanic lands of Galapagos, bird disperse fleshy fruits by
defecation.
Two iguanas; one has radiated into the marine world. These have evolved mechanisms to deal with
salinity. The other specie eats the prickly pear cactus.
Australia
It͛s a ĐoŶtiŶeŶt aŶd aŶ islaŶd; has ŵaŶLJ uŶiƋue adaptatioŶs aŶd high leǀels of eŶdeŵisŵs i.e. speĐies aƌe
restricted to that area. Unique because of isolation. Gene flow has been restricted and without gene
flow lineages are restricted. The tropical forests look like the others in the world; as a result of
convergent evolution. Gum trees are very common; endemic to Australia. These burn very easily;
contain chemicals which make the super combustible. Koalas have gum trees in their diet and they
detoxify the leaves. Banksia is another life form in Australia which is an endemic and is pollinated by
rodents.
Lecture 4
Saturday, October 3, 2015
5:40 PM
McClintock
DisĐoǀeƌed ͚juŵpiŶg geŶes͛ iŶ ŵaize. DetaĐh fƌoŵ geŶoŵe aŶd ŵoǀe to aŶotheƌ plaǀe. TheLJ aƌise fƌoŵ
mutations. They are transposable elements.
Mendel
His research contributed to our knowledge about how genes are transmitted. He saw traits were
discontinuous. Discontinuous variability – two distinct variations, no intermediate. Inheritance is
determined by discrete variables – genes. Particulate Inheritance – two copies of each gene.
Fisher
Genotype
Genetic constitution of an organism. For example, Aa.
Phenotype
What you can see.
Genome
DNA
Gene
Functional unit of inheritance, unit of hereditary information located on chromosomes, DNA sequence
composed of codons. Code for protein which make up an organism. Very important.
Allele
Mutation
find more resources at oneclass.com
find more resources at oneclass.comUltimate source of genetic variation. But if we study a given population, there can be other factors
which mix up the variation. Mutations are often neutral in one environment and deadly/beneficial in
another; these are context dependent.
Point mutations, a common form, there is a change in a single nucleotide.
Jumping genes, an insertion or deletion
Repeats of nucleotides giving rise to a class of variability
Chromosomal rearrangements, the most drastic kind of mutations. The genes are mistaken; not able to
make protein, do not contain the right information. This is a very dramatic mutation. Instead of the
organism being diploid, they are tetraploid.
Rates of mutations are not fixed.
Recombination
Types of Mutation
Homeotic mutation – basis of evo devo.
SEE MUTATIONS
Transposable Genetic Elements
Fitness Effects of Mutations
Blending and Particulate Inheritance
The latter refers to the fact that each individual carries a copy of a gene from one parent and the other
half from the other parent.
Discrete vs. Continuous Traits
In some cases, traits are not simply inherited. Continuous traits include height, weight. The differences
are continuous because the trait is controlled by many genes. Continuous are controlled by many genes.
Each of these has an impact on the phenotype.
Mendelian vs. Quantitative Inheritance
Fisher’s FuŶdaŵeŶtal Theoreŵ
Brought genetic into evolution. States that the rate of increase in a fitness of a population at any time is
equal to its genetic fitness.
Not all genes mutate at the same frequency. It varies between species.
MutatioŶs aƌe ĐoŶtedžt depeŶdeŶt. EĐologLJ aŶd eǀolutioŶ aƌe iŶteƌtǁiŶed ďeĐause theƌe͛s Ŷo suĐh thiŶg
as an organism that does not live.
Most genetic variation comes from sex. Mutation gives very little genetic variation.
Polymorphism
When we have discrete traits which can be put into categories, we call that a polymorphism. Because
the differences are genetic, it is a genetic polymorphism. If there is coexistence of two forms, this is
polymorphism. Two different forms; no intermediate. DOES NOT APPLY TO HEIGHT.
Discontinuous Variation
If one or two genes control a trait; Mendelian traits. Genes of large effect, controlling an entire
phenotype. At the population level, this is polymorphism.
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find more resources at oneclass.comLecture 5
Saturday, October 3, 2015
3:20 PM
Measuring genetic variation is easier when you have polymorphism since you can easily tell which trait is varying
for example, colour.
Fisher, Haldane, Wright
Bring into evolutionary biology genetics by mathematical contributions. Showed that continuous variation and
DaƌǁiŶiaŶ Ŷatuƌal seleĐtioŶ ǁeƌe ĐoŶsisteŶt ǁith MeŶdel͛s laǁs. Demonstrate role of genetic variation in
evolution.
Their approach revealed how mutations arise and, if they are favoured by natural selection. Wright introduced the
͚adaptiǀe laŶdsĐape͛; the ǀaƌLJiŶg fitŶess of diffeƌeŶt ĐoŵďiŶatioŶs of geŶes as a hillLJ laŶdsĐape, the ǀalleLJs
representing less-fit combinations and the peaks representing the fitter ones. Natural selection moves population
towards the peak of the hills.
Morgan
Bred fruit flies and tried to create mutant flies with x-rays, acid etc. Saw the sudden occurrence of white eyes. He
realized that a gene had been altered and it had produced a new kind of eye. He then bred the
white-eyed fly with a red-eyed fly and got a generation of red-eyed hybrids and when he bred
these, the resulting generation consisted of white-eyed flies. He established a new science;
genetics [Show Less]