Lamarck is Silly

1
Lamarck is Silly
2
Evolution

• Lesson 3

3
Summary of Darwins Theory Evolution

• Observation Individuals of a population vary
  extensively in their characteristics with no two
  individuals being exactly alike.
• Observation Much of this variation between
  individuals is heritable.

4
Variation and Heritability

• -Differences between individual organisms exist
  due to differences in genetics.
• -These genetic differences arise from genetic
  mutations.

5
Variation and Heritability

• Mutations are not all good. Many of them do
  nothing at all, while others are absolutely
  harmful. Mutations occur randomly and have
  random effects.
• When a mutant breeds, these genetic mutations
  are inherited by the offspring.
• Examples Extra Fingers, Sickle Cell Anemia

6
Examples Mutations
Extra Fingers (Polydactyl)
Sickle Cell Anemia
7
Genetic Change Key Terms

• Gene Particular parts of DNA that results in
  traits.
• Gene Pool The combined collection of genes for
  all traits in a population.
• Genetic Equilibrium Occurs when the gene
  frequencies are stable from generation to
  generation
• Bell Curve The shape of a graph depicting a
  normal distribution of genes

8
Gene Pool

• Gene Pool The combined collection of genes for
  all traits in a population.

9
Genetic Equilibrium

• No Fur Average Fur Thick Fur
• G1 15 30 15
• G2 30 60 30
• G3 15 30 15

10
Bell Curve
11
Bell Curve Male Height
12
Bell Curve Female Height
13
Flash

• Which are closer in height to one another?
• A Males
• B Females

14
Bell Curve Male Height
15
Bell Curve Female Height
16
Natural Selection and Genetic Equilibrium

• Natural Selection can affect a Gene Pool (and
  Bell Curve) in 3 ways.
• Directional Selection Individuals at one end
  of the curve have higher fitness than those in
  the center or at the other end.
• Stabilizing Selection Individuals near the
  center of the curve have higher fitness than
  those at either end.
• Disruptive Selection Individuals at both end of
  the curve have higher fitness than those in the
  center.

17
Three Forms of Natural Selection
18
Flash

• If Lions in Africa are unable to attack the
  largest elephants, what kind of natural selection
  will occur?
• A Stabilizing
• B Directional
• C Disruptive

19
Flash

• Fashion writers publish an article saying that
  the fur from small rabbits is too fine, while
  that from large rabbits is too coarse. Trappers
  now want only average rabbits.
• A Stabilizing
• B Directional
• C Disruptive

20
Flash

• In a school of fish, those that are too big stand
  out, while those that are too small struggle to
  keep up. As a result, the largest and smallest
  fish are eaten.
• A Stabilizing
• B Directional
• C Disruptive

21
Sexual Selection

• Sexual Selection A special case of selection
  that occurs when the choice of mates is based on
  a trait (or traits). Sexual selection may be
  directional, stabilizing, or disruptive.

22
Sexual Selection
23
The Hardy-Weinberg Principle

• The Hardy-Weinberg Principle states the
  conditions necessary for a population to remain
  in Genetic Equilibrium. If all the conditions
  are not met then evolution will occur.

24
The Hardy-Weinberg Principle

• Random Mating Sexual selection will alter the
  Gene Pool.
• Large Population Small populations lead to
  random fluctuations of the Gene Pool.
• No Mutation Genetic mutations add new genes the
  Gene Pool.
• No Migration Individuals entering or leaving a
  population adds or subtracts genes from the Gene
  Pool.
• No Natural Selection All individuals in the
  population must have an equal chance at surviving
  and reproducing.

25
Evolving New Species

• Speciation The evolution of a new species.
• In order for speciation to occur, populations (or
  segments of populations) must become
  reproductively isolated.
• There are 3 ways that a population can become
  reproductively isolated.

26
Reproductive Isolation

• Behavioral Isolation Occurs when two
  populations are physically capable of
  interbreeding, but have different reproductive
  behaviors.
• Geographic Isolation Occurs when a physical
  barrier (mountain, lake, etc.) separates two
  populations.
• Temporal Isolation Occurs when populations are
  capable of interbreeding, but each breed at
  different times.

27
Behavioral Isolation
28
Geographic Isolation
29
Geographic Isolation
30
Temporal Isolation
31
Flash

• Mark and Jane work together at Blockbuster. Mark
  likes Jane and wants to ask her out on a date.
• Before he gets the chance, his family moves to
  another state. Mark has to quit his job and he
  never sees Jane again.
• A Behavioral Isolation
• B Geographic Isolation
• C Temporal Isolation

32
Flash

• Mark and Jane work together at Blockbuster. Mark
  wants to ask her out on a date.
• Mark shows Jane his collection of StarWars toys
  to impress her. Jane says that Mark is a dork
  and makes fun of him.
• A Behavioral Isolation
• B Geographic Isolation
• C Temporal Isolation

33
Flash

• Mark and Jane work together at Blockbuster. Mark
  wants to ask her out on a date.
• Before Mark has a chance to ask her out, his boss
  switches their schedules so that they work at
  different times.
• A Behavioral Isolation
• B Geographic Isolation
• C Temporal Isolation

34
Convergent and Divergent Evolution

• Convergent Evolution Two unrelated species
  develop similar traits due to similar
  environments. Convergent evolution causes
  Analogy.
• Divergent Evolution Two similar species develop
  differences due to different environments.
  Divergent Evolution causes Homology.

35
Convergent Evolution
36
Divergent Evolution
Flying
Swimming
Running
Grasping
37
Review

• Types of Selection
• Stabilizing, Disruptive, Directional
• Sexual
• Hardy-Weinberg Equilibrium
• Explains 5 conditions for when evolution does not
  occur.
• Speciation
• Requires reproductive Isolation
• Geographic, Temporal, Behavioral
• Divergence and Convergence
• Result in Analogy and Homology