1. Natural Selection
Pre-AP Biology

2. Addie’s Case – Patterns
Addie was cut while playing on the playground in 2011.
She went to the hospital after becoming sick due to an infection caused by one type of bacteria from this cut.
Doctors gave her an antibiotic that worked for a while, but then stopped working.
She ended up getting another infection from a different type of bacteria while in the hospital.
Doctors then gave her a different antibiotic that worked for a while, but then it stopped being effective and Addie got sicker. They tried a third antibiotic and Addie started to improve, but this antibiotic also stopped being effective and she got worse once again.
They repeated this process trying every antibiotic available to them.

3. Addie’s Case - Types of Bacteria
Two different species – Staphylococcus and Stenotrophomonas
Some of both kinds of bacteria appear to have been killed by antibiotics. On the other hand, some of both kinds of bacteria were not killed by those antibiotics.
It appears that there are two types of bacteria within each species —those that are resistant to an antibiotic (and lived) and those that are not resistant to an antibiotic (and died).

4. Addie’s Case - Antibiotic Cycles
New Antibiotic
Got better
Got Worse
Pan-Resistant Bacteria

5. Learning Goals 1. Define "Evolution" & "Natural Selection".
2. Describe the 4 steps of Natural Selection, giving an example of each.
3. Explain the importance of "Variation".
4. Does Natural Selection act on an organism phenotype or genotoype? Explain!
5. List the 5 evidences that support the Theory of Evolution.

6. Theory of Evolution Evolution: The process of change over time
Specifically, a change in the frequency of a gene or allele in a population over time

7. Charles Darwin Father of Evolution
Proposed a mechanism for evolution, natural selection
Darwin went on a 5-year trip around the world on the ship, the HMS Beagle
As the ship’s naturalist, he made observations of organisms in South America and the Galapagos Islands
Wrote a book, “Origin of the Species”

8. Darwin’s Finches
The shape of the beak is adapted to the diet and environment of the finch.
Each finch ate a different diet so they occupied a different niche and created less competition.

9. Natural Selection
Natural Selection: Organisms that are best adapted to an environment survive and reproduce more than others
Adaptation: an inherited trait that increases an organism’s chances of survival
Behavior, Physical, or Physiological traits
Darwin’s Theory of Natural Selection occurs in four steps:
Overproduction
Variation
Competition
Selection

10. What adaptations do you see?

11. 1. Overproduction
Each species produces more offspring that can survive

12. 2. Variation
Each individual has a unique combination of inherited traits from their parents.

13. Why is Variation Important?
Because the environment changes.
The more variation within a species, the more likely it will survive
EX: If everyone is the same, they are all vulnerable to the same environmental changes or diseases
The more variation of types of species in an habitat, the more likely at least some will survive
EX: Dinosaurs replaced by mammals

14. Which community has a better chance of surviving a natural disaster?
Community A
Community B

15. 3. Competition Fitness: the ability to survive and reproduce
Individuals COMPETE for limited resources:
Food, water, space, mates
Natural selection occurs through “Survival of the fittest”
Fitness: the ability to survive and reproduce
Not all individuals survive to adulthood

16. 4. Selection
The individuals with the best traits / adaptations will survive and have the opportunity to pass on it’s traits to offspring.
Natural selection acts on the phenotype (physical appearance), not the genotype (genetic makeup)
Ex: When a predator finds its prey, it is due to the prey’s physical characteristics, like color or slow speed, not the alleles (BB, Bb)

17. Individuals with traits that are not well suited to their environment either die or leave few offspring.
Evolution occurs when good traits build up in a population over many generations and bad traits are eliminated by the death of the individuals.

22. Peppered Moth A
Which moth will the bird catch? B

23. Descent with Modification
Descent with Modification – each living species has descended, with changes, from other species over time.
Common Descent – all living organisms are related to one another

24. Cladogram: Shows evolutionary relationships and common ancestry.

25. Evidence for Evolution:
Fossil Record
Homologous Body Structures
Vestigial Organs
Embryology
Biochemical Evidence

26. The Fossil Record
Fossils: a record of the history of life on Earth

27. Archaeopteryx
Missing link between reptiles and birds

28. Pangea

29. Homologous Body Structures
Homologous Body Structures: similar anatomy in different types of animals because of common ancestor

31. Vestigial Structures
Vestigial Structures: “leftover” traces of evolution that serve no purpose or function

33. Embryology
Embryology: embryos of all vertebrates are very similar early on

35. Biochemical Evidence
Biochemistry: DNA with more similar sequences suggest species are more closely related
EX: Humans and chimpanzees share more than 98% of identical DNA sequences

36. Speciation is the formation of new species
Speciation is the formation of new species. A species is a group of organisms that breed with one another and produce fertile offspring.

37. Isolating Mechanisms
As new species evolve, populations become reproductively isolated from each other.
When the members of two populations cannot interbreed and produce fertile offspring, reproductive isolation has occurred. (3 types)

38. Behavioral Isolation 
Behavioral isolation occurs when two populations are capable of interbreeding but have differences in courtship rituals or other reproductive strategies that involve behavior.

39. Geographic Isolation 
Geographic isolation occurs when two populations are separated by geographic barriers such as rivers or mountains.

40. Copyright Pearson Prentice Hall

41. Temporal Isolation Temporal isolation occurs when two or more species reproduce at different times.

43. Coral Snake (Venomous)
Milk Snake (Not Venomous)

49. Stick Mantid

50. Flower Mantid