1. Species Variation

2. Scientists know Earth has changed over time
Scientists know Earth has changed over time. Scientists estimate that Earth is billion years old.
We also know that as populations have changed over time(adaptations), new species form and other species die out (go extinct).
Newer species descend from older species.

3. Evolution as Theory and Fact
Confusion sometimes arises as to
whether Evolution is a theory or a fact.
Actually it is both!
The theory of Evolution deals with how
Evolution happens. Our understanding
of this process is always changing.
Evolution is also a fact as there is a
huge amount of indisputable evidence
for its occurrence.
Presenter notes: There is often considerable confusion as to whether the concept of evolution is a theory or a fact. Actually it is both! Evolutionary theory deals with how evolution happens. This is an area of active research and new insights are constantly emerging to explain how one species gives rise to another. However, Evolution is also a fact because there is a great deal of indisputable evidence, as we will see in this talk, in support of its occurrence. What is uncertain is exactly HOW it happens, NOT whether it has happened at all.
Further background reading: Stephen Jay Gould, "Evolution as Fact and Theory," Discover 2 (May 1981): 34-37; available here:
Rodin’s “The Thinker”

4. Fixed species Michelangelo’s fresco on the ceiling
of the Sistine Chapel
Presenter notes: So let’s start by thinking about the discovery of Evolution. Beginning in Classical times and persisting until long after the Renaissance, scientists thought species were fixed and unchangeable (or ‘immutable’ to use the language of the era). Their reasoning ran something like this: if God’s creation was perfect from the start, why would He bother to tinker with it at a later date?
en.wikipedia.org/wiki/The_Creation_of_Adam
From Classical times until long after the Renaissance, species
were considered to be special creations, fixed for all time.

5. Evolution-
is change in the inheritable traits of biological populations over successive generations (gradual change over time)
Evolutionary processes give rise to diversity at every level of biological organization, including the levels of species, individual organisms, and molecules.

6. Generation
A population of offspring that are all born around the same time period.

7. Darwin’s Voyage From 1831-1836, a young naturalist called
Charles Darwin toured
the world in HMS
Beagle.
He was dazzled by the
amazing diversity of
life and started to
wonder how it might
have originated
Presenter notes: In the early nineteenth century, Charles Darwin ( ) rekindled ideas about evolution. In a sense, Evolution was in Darwin’s blood because, as we’ve already noted, his grandfather was an early supporter of the concept. From , Darwin toured the world on HMS Beagle as a young naturalist. He was dazzled by the amazing diversity of life, including some amazing fossils such as rodents the size of hippopotamuses and started to wonder how it might have originated.
Voyage of the Beagle
en.wikipedia.org/wiki/Image:Charles_Darwin_by_G._Richmond.jpg
en.wikipedia.org/wiki/Image:HMS_Beagle_by_Conrad_Martens.jpg

8. Also known as survival of the fittest
Natural Selection
Darwin proposed that evolution happens through a process called natural selection.
Natural selection- the process by which individuals better adapted to their environment survive and reproduce more successfully than less well adapted individuals do.
Also known as survival of the fittest

9. How Adaptation occurs…
All in the Genes
The genetic make-up of
an organism is known as
its genotype.
An organism’s genotype
and the environment in
which it lives determines
its total characteristic traits
i.e. its phenotype.
Presenter notes: In this second part of the talk, we will think about the mechanism of evolution, or to put it more simply, how evolution works. Earlier, we’ve mentioned the importance of genetics in the discovery of Evolution, and we’ll think much more about that over the next few slides. But first of all, let’s introduce ourselves to a few technical terms. The genetic make-up of an organism is known as its genotype. The genotype of an organism and the environment in which it lives (nature and nurture together) determine the characteristic traits of the organism, or its phenotype.
Genotype
Phenotype
commons.wikimedia.org/wiki/Image:DNA_double_helix_vertikal.PNG

10. Mutation However, occasional Types of mutation
mutations or copying errors
can and do occur when
DNA is replicated.
Mutations may be caused
by radiation, viruses, or
carcinogens.
Mutations are rare and often have
damaging effects. Consequently organisms
have special enzymes whose job it is to
repair faulty DNA.
Types of mutation
Mutant fruitfly
Presenter notes: However, very occasionally, tiny copying errors can and do occur when DNA is replicated. These copying errors are called mutations. Mutations may be caused by a number of factors including radiation, viruses, or carcinogens (cancer-causing materials). As the genotype provides the blueprint for how each cell should grow and function, even a tiny mutation might mean that the cells fail to work properly. Take for example the common fruitfly: a single mutation in the fruitfly can change the colour of the eye from red (its normal colour) to white. White-eyed fruitfly are less successful at mating. Because of the potential for mutation, most organisms have a group of special enzymes whose job it is to go round and repair any faulty DNA.
upload.wikimedia.org/wikipedia/commons/7/79/Types-of-mutation.png humansystemstherapeutics.com/bb.htm

11. Variation
Some mutations will persist and increase genetic variation within a population.
For example, the one of
the genes for hair colour
comprises brown/blonde
alleles.
Presenter notes: Mutations give rise to variants, or alleles, of the same gene. One person may have one set of alleles, and another person, a different set. For example, take hair colour in humans. One of the genes that codes for hair colour occurs as two alleles, brown and blonde. If you throw you mind back to earlier in this talk you’ll remember how Mendel showed that one allele is usually dominant and the other recessive. In the case of hair colour, brown is dominant and blonde is recessive. So if a person gets a brown allele from one parent and a blonde allele from the other parent, they will have brown hair. A person will only have blonde hair where they receive blonde alleles from both parents.
majorityrights.com/index.php/weblog/comments/racial_variation_in_some_parts_of_the_skull_involved_in_chewing/

12. Natural Selection Mutant alleles spread through a
population by sexual reproduction.
If an allele exerts a harmful effect,
it will reduce the ability of the
individual to reproduce and the
allele will probably be removed
from the population.
In contrast, mutations with favorable
effects are passed on
Selection of dark gene
Presenter notes: If a person, or any other organism for that matter, develops a new allele (a mutation), they can spread this around the population by sexual reproduction. However, if the allele exerts a harmful effect on the individual then this will reduce the likelihood of it reproducing and the allele will be removed from the population. Only those mutant alleles that have beneficial effects that increase the likelihood of reproduction will be passed on to offspring. In this way, harmful alleles are removed from a population while favorable alleles accumulate. This is Darwin’s concept of Natural Selection and shows how a population adapts to its environment over time.
en.wikipedia.org/wiki/Image:Mutation_and_selection_diagram.svg

13. Example: Peppered Moth
Haldane and the peppered moth
The Peppered Moth is an
example of Natural Selection
in action discovered by Haldane
During the Industrial Revolution
the trees on which the moth
rested became soot-covered.  
Presenter notes: The case of the Peppered Moth is an excellent example of Darwin’s Natural Selection in action put forward by the biologist J.B.S. Haldane in The gene that controls the colour of the Peppered Moth occurs as two alleles, a mottled allele (pale colour) and a melanic allele (black colour). Early in the 18th century, pale moths were dominant in the countryside around Manchester. However, during the Industrial Revolution the trees on which the moths rested became covered in black soot. Pale mottled moths were poorly camouflaged on the black tree trunks and were preferentially eaten by birds. In contrast, the black melanic moths were better at avoiding predation. Natural Selection acted against the pale moths and in only a few generations, the melanic moths were dominant. However, there was one final twist. As the skies of Manchester became cleaner in the 20th century, the mottled moths made a comeback and displaced the melanic moths again.
This selected against the allele for pale
colour in the population (which were
poorly camouflaged from predators)
and selected for the dark colour allele.
en.wikipedia.org/wiki/Image:Biston.betularia.f.carbonaria.7209.jpg
en.wikipedia.org/wiki/J._B._S._Haldane

14. Speciation- formation of new species as a result of evolution
The three steps of speciation are:
1. Isolation/Separation (part of a population becomes separated from the
rest due to a landform or human activities such as roads)
2. Adaptation (the separated group may evolve different sets of traits )

15. 3. Division (two separated groups may become very different; groups may not be able to interbreed anymore)

16. Microevolution The dog is another example of how
selection can change the frequency
of alleles in a population.
All breeds of dog belong to the same
species, Canis lupus (the wolf) so this
is an example of Microevolution as no
new species has resulted.
Dogs have been artificially selected
for certain characteristics for many
years, and different breeds have
different alleles.
Presenter notes: The case of the Peppered Moth shows how natural selection can change the frequency (or relative proportion) of alleles in a population. A more straightforward example of the same phenomenon is the breeding of dogs. Humans have been breeding dogs for thousands of years and trying to develop certain characteristics. This “artificial selection” is exactly the same process as natural selection but controlled by human intention rather than natural forces. Although humans have been successful in changing the frequency of alleles in different dog breeds, they haven’t created new species. The definition of a species is a population that can interbreed and produce fertile offspring. Most dogs can successively interbreed with other dogs, and also with wolves, so in actual fact all dog breeds are just subspecies of the wolf, Canis lupus! Dog breeding is therefore an example of what biologists called Microevolution; the frequency of alleles in the population have changed, but not greatly enough to give rise to a new species.
Dogs are wolves

17. Macroevolution However, if two populations of a
species become isolated from
one another for tens of thousands
of years, genetic difference may
become marked.
If the two populations can no-longer
interbreed, new species are born.
This is called Macroevolution.
Darwin’s Galapagos finches are
an example of this process in action.
Galapagos finches
Presenter notes: To give rise to a new species, Microevolution needs to go on for more much longer than humans have been breeding dogs. For example, if a species was to become divided into two isolated populations for tens of thousands of years, then natural selection would eventually change the frequency of alleles to such an extent that members of the two populations could no longer interbreed. This process would result in the birth of new species or speciation. Where speciation occurs, biologists refer to the process as Macroevolution. An excellent example of Macroevolution is that observed by Charles Darwin during his world tour on HMS Beagle. When visiting the Galapagos Islands in the Pacific Ocean he noticed that each island had its own distinctive species of finch. Darwin argued that the islands had originally been colonized by just one species of finch, but then in isolation, each island population had evolved in response to different environmental conditions.

18. Speciation Today? The mosquito was introduced to
the London Underground during
its construction around 1900.
It became infamous in the War
for attacking people sheltering
from the Blitz.
Studies indicate several genetic
differences from its above-ground
ancestors. Interbreeding between
populations is difficult suggesting
that speciation may be occurring.
London Underground Mosquito
Presenter notes: An obvious question as we conclude our look at how evolution works is: are there any examples of evolution by natural selection going on today. Obviously, the answer is yes, as all species are undergoing evolution. However, as the rate of change is very slow, examples are very difficult to detect and even harder to prove. One possible example is the case of the ‘London Underground Mosquito’. This mosquito found its way into the Tube system around 1900 when the railway lines were being constructed. It became infamous during the Second World War as it would constantly bite people sheltering from the Blitz. The London Underground Mosquito has been isolated from the surface for over a hundred years and studies indicate that there are already genetic differences between it and its above-ground relatives. The differences are so great that the two populations have difficulty interbreeding. Perhaps here is an example of ongoing speciation today?
en.wikipedia.org/wiki/Image:Gb-lu-Angel-southbound.jpg
en.wikipedia.org/wiki/Culex

19. Separation refers to species being separated
Separation refers to species being separated. It stops populations from interbreeding so new species evolve
Isolated populations can be unable to interact with each other because of geographic boundaries like an ocean or mountain. They can develop unique characteristics and cannot interbreed.
Two populations can be isolated if they feed at different times or reproduce at different times of the year.
Two or more populations may evolve differently from each other.

20. Adaptation- a characteristic that improves an individual’s ability to survive and reproduce in a particular environment.
Adaptations may be physical (change in appearance), such as a long neck or striped fur. Adaptations may be behaviors that help an organism find food, protect itself, or reproduce.

21. Suppression
Suppression can be another form of a physical adaptation…Supression is the absence or non-development of a part or organ that is normally present. (Ex: Snakes used to have feet.)

22. Predominance
The quality or state of being superior or having more prevalence over other organisms or organisms in their own species.

23. Antibiotic resistance
Staphylococcus
We are all familiar with
the way that certain
bacteria can become
resistant to antibiotics
This is an example of natural selection in
action. The antibiotic acts as an
environmental pressure. It weeds out
those bacteria with low resistance and
only those with high resistance survive
to reproduce.
Presenter notes: A final and perhaps especially convincing piece of evidence for evolution is the familiar way that bacteria may become resistant to antibiotics. Bacteria have a fast life cycle and can produce a new generation every 4 hours. As natural selection acts on each generation this means bacteria can rapidly respond to environmental pressures. In effect the antibiotics act to weed out those bacteria with low resistance in each generation. Only bacteria with high resistance survive and pass their alleles to the next generation. Consequently, in just a short time, natural selection increases the resistance level of the bacteria population. This is an example of evolution in action amongst the simplest organisms on our planet – and then having an impact on the most complex organisms!
en.wikipedia.org/wiki/Image:Staphylococcus_aureus%2C_50%2C000x%2C_USDA%2C_ARS%2C_EMU.jpg

24. Genetic Resistance-When an organism changes or adapts to factors such as the environment, antibiotics, insecticides, and pollution to survive.

25. Extinct-describes a species that has died out completely with no one individual left to carry on the species’ population.
Most scientists think that the extinction of dinosaurs happened because of extreme changes in the climate of the Earth. These changes could have resulted from a giant meteorite hitting the Earth or forces within the Earth could have caused many volcanoes and earthquakes.