Charles Darwin (1809-1882) was an English naturalist who proposed the theory of evolution by natural selection. Darwin spent five years on a voyage around the world, with most of his time spent in South America and neighboring islands. For more information, access the provided Wikipedia link about Charles Darwin.

1. Charles Darwin (1809--1882) was an English naturalist and is credited for proposing that
the mechanism for the process of evolution is natural selection. Darwin spent five
years on a voyage that took him around the world with the majority of his time spent in
South America and its neighboring islands. For more information access this link:
http://en.wikipedia.org/wiki/Charles_Darwin

2. 11/08/15
Emphasize that the fossil record clearly shows that species change over time. What we
now know is how evolution happens. Evolution occurs within the gene pool of a
species (not to be confused with individuals).
Ask students to examine the frogs. Ask them how many phenotypes exist (three). Have
them list them (red, green, blue). Ask them to examine the gene pool. They should
notice only two types of genes red or green. So, why are some frogs blue??

3. 11/08/15
Have students tally the number of frogs of each color before moving to the next slide!
Allele frequency calculations follow on the next slide.

4. 11/08/15
Be sure to connect that the frequencies are the p and q of the Hardy-Weinberg
equilibrium equation. Students don’t usually make that connection on their own.
Introducing 4 new green frogs changes the population. Now, there are 15 green frogs,
2 blue and 3 red. (20 individuals, thus 40 alleles)
Have students “do the math” before moving to the next slide.
You can also survey the room to determine the gene pool for human eye color in your
classroom population. Use B and b for the alleles. When a brown-eyed student is
found, ask them the phenotype of their parents. If one is blue, then you know that the
student is Bb.

5. 11/08/15
What do we conclude? Did the allelic frequencies change? Yep! That indicates
evolution occurred.
You can also revisit your brown eyed problem by asking them what happens if 6 blue-
eyed students joined the population. Let them determine how the allele frequency will
change.

6. 11/08/15
Some would argue that the words immigrate and emigrate apply only to human
populations.

7. 11/08/15
What do we conclude? Did the allelic frequencies change? Yep! That indicates
evolution occurred.
Emphasize that allele frequencies can be changed by gene flow OR emigration and
immigration occurring. Now, what would happen if four green frogs joined the
population but the population was twice as large as the original population?

8. 11/08/15
The next few slides are investigating the effect of large versus small sample size. What
happens to the allelic frequencies when the frog population is twice as large. Have
students tally the frogs prior to moving to the next slide.
Additionally, you can ask the students what happens to the allele frequency in the
classroom population if the six blue-eyed students joined the school gene pool instead
of just the class gene pool. (It would not have as great an effect since the school
population is much larger than the class population.)

9. 11/08/15
There is a change in allelic frequency, but it is a relatively small change (0.02). Evolution
does still occur.

10. 11/08/15
There is a more dramatic effect on allelic frequency upon addition of four green frogs
to the small population. The change in frequency is 0.05 for the small population
compared to 0.02 for the larger population which is more than twice as much!

11. 11/08/15
The diagram is showing how genes can become fixed in gene pool.

12. 11/08/15
Populations that experience a bottleneck effect or a founder effect are usually more
susceptible to genetic drift. Genetic drift can lead to the existence of completely
separate subpopulations (genetically). However, it is important to note that even large
populations can experience genetic drift. This is relatively new in more recent books.

13. 11/08/15
Populations that experience a bottleneck effect or a founder effect are usually more
susceptible to genetic drift. Sometimes it’s a social pressure among humans in
particular. The instances of hemophilia among the British royal family for instance.
“Pressure” was (and in some cases still is) placed on members of the Royal Family to
marry only Royals. The result is that genes become magnified since there is a reduction
in genetic diversity.

14. 11/08/15
Emphasize that a reduction in genetic diversity has a negative impact on offspring.
For example, most deleterious alleles like cystic fibrosis are recessive. If these negative
genes are ones that are left in the reduced gene pool then it increases the probability
that they will be expressed.

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The new, yet small population colonizes the area.

16. 11/08/15
http://io9.com/the-founder-effect/

17. 11/08/15
http://io9.com/the-founder-effect/

18. 11/08/15
Another interesting American case of the Founder
Effect involves the Fugates of Troublesome Creek in
Kentucky.
http://www.rootsweb.ancestry.com/~kyperry3/Blue
_Fugates_Troublesome_Creek.html and
http://news.yahoo.com/humans-eventually-look-
brazilians-140349518.html

19. 11/08/15
Random mating is the exception rather than the norm. Most mating is nonrandom.
Emphasize that time and space also factor into nonrandom mating. For example, pollen
from Ohio is more likely to cross pollinate a neighboring tree in Ohio rather than a tree
in Oregon. However, truly nonrandom mating would imply that these events would
have an equal probability.

20. 11/08/15
Emphasize that in addition to a flashy appearance males often have vocalizations and
compete with other males to attract females.

21. 11/08/15
Emphasize a gene is determined beneficial if it gives an organism an advantage which
depends entirely on the environment.

22. 11/08/15
Godfrey Hardy (1877-1947), an English mathematician, and Wilhelm Weinberg (1862-
1937), a German physician, both found a way to link genetic probability and evolution
the early 20th century. Hardy and Weinberg independently worked on finding a
mathematical equation to explain the link between genetic equilibrium and evolution in
a population of species.

23. 11/08/15
This slide and the next slide explain that three of the five conditions for Hardy-
Weinberg can never be met, therefore evolution occurs within populations.

24. 11/08/15
The next three slide derive the Hardy-Weinberg equilibrium.

25. 11/08/15
As long as the allelic frequencies are remaining constant, there is no evolution of the
population.

26. 11/08/15
Whoever said “It isn’t easy being green?”

27. 11/08/15
Ask students if they know the “FOIL” method for solving (p + q)2
. FOIL stands for “first
by the first, outsides, insides, second by the second.” It’s a mnemonic device math
teachers use to teach binomial expansions and arrive at p2
+ 2pq + q2
which equals 1
in this situation since p + q = 1, thus (p + q)2 =
12
= 1 as well, and gives this algebraic
expression: p2
+ 2pq + q2
. It may have been a while since your last Algebra class, but it
hasn’t been that long since students mastered this skill!
This pair of equations along with a subsequent Chi square calculation allow us to
determine if a population is in H-W equilibrium.

28. 11/08/15
Emphasize to students that the phrases “survival of the fittest” and “struggle for
existence” are commonly used to describe natural selection, BUT they should not be
taken to mean between individuals! There are reproductive advantages among animals
that are passive and do not involve a form of battle:
•An animal may be a better “food gatherer”, thus has more energy to lay more eggs.
•An animal may be better camouflaged, thus lives longer and produces more offspring.

29. 11/08/15
The next few slides deal with a hypothetical deer mouse population with heritable
variation in fur coloration from light to dark.
Emphasize to students that the width of the curve corresponds to variance (numerical
range of the x-axis) and the “peak” corresponds to the mean (corresponds to the
numerical value on the y-axis). This type of curve goes by many names: normal
distribution, bell curve, optimum, etc.
When a particular trait confers an advantage to an organism in a given environment,
then one would expect a change in the gene pool over time. The next slides explain the
three types of selection with examples for each type illustrating how the gene pool

30. 11/08/15
Emphasize that the arrow symbolizes selective pressures AGAINST certain phenotypes.
Ask students to interpret the “before and the after” regarding these two graphs. Ask
“What’s the scoop?” They should conclude that the environment changed such that
the lighter mice were selected against. Perhaps they live among dark rocks, etc. which
makes it harder for them to hide from predators. Revisit the peppered moth as an
example of directional selection.

31. 11/08/15
Ask students to propose possible consequences of continual directional selection
(extinction or speciation).

32. 11/08/15
The mice in (b) have colonized a patchy habitat made up of light and dark rocks, with
the result that mice of an intermediate color are selected AGAINST as indicated by the
arrow.
This art is from the 8th
edition of Campbell, revised art from the 9th
edition has (b)
labeled as “Disruptive selection”. Once again, synonyms are troublesome for students!

33. 11/08/15
The mice in (b) have colonized a patchy habitat made up of light and dark rocks, with
the result that mice of an intermediate color are selected AGAINST as indicated by the
arrow.
This art is from the 8th
edition of Campbell, revised art from the 9th
edition has (b)
labeled as “Disruptive selection”. Once again, synonyms are troublesome for students!

34. 11/08/15
Ask students to explain the significance of the shape change of the graph in (c). They
should point out that the value of the mean has increased and the variance of the
population has decreased.
If the environment consists of rocks of an intermediate color, both light and dark mice
will be selected AGAINST.

35. 11/08/15
Ask students to identify “differences in secondary sexual characteristics”. Possible
answers include: size, color, ornamentation and behavior.

36. 11/08/15
Remind students that the prefix intra- means “within” as opposed to the prefix inter-
which means “between” as in interstate highways that connect states. HI and AK don’t
have those types of highways!
Ask student to come up with examples of intrasexual selection: patrolling a group of
females, male to male combat, marking a territory, etc.

37. 11/08/15
Ask student to come up with examples of showiness and its possible consequences:
bright coloration—sacrifice of camouflage, mating call or song—alerting would be
predators of the prey’s location, etc.

38. 11/08/15
Genetic variation in a gene pool is beneficial. The question is how certain populations
can maintain genetic variation. These next slides explain how genetic variation can be
maintained.

39. 11/08/15
Recessive alleles might not be favored under present environmental conditions, but can
still bring new benefits if the environment changes.

40. 11/08/15
Recessive alleles might not be favored under present environmental conditions, but can
still bring new benefits if the environment changes.

41. 11/08/15
Natural selection may favor non-poisonous butterflies that have the same color pattern
as poisonous butterflies. This system is called Batesian mimicry. When they are rare,
birds will tend to avoid the mimics, because they will have already have encountered a
poisonous butterfly of the same appearance. But when the non-poisonous type is
common, the previous encounters of birds with butterflies of their appearance are
more likely to have been rewarding; the birds will not avoid eating them, and their
fitness will be lower. The fitness of the mimics is negatively frequency-dependent.

42. 11/08/15
Though natural selection leads to adaptation, nature abounds with examples of
organisms that are less than ideally “engineered” for their lifestyles.

43. 11/08/15
With these 4 constraints, evolution does not tend to craft perfect organisms. Natural
selection operates on a “better than” basis. As a result, many organisms contain
imperfections.