1. Do Now
Bacillus thuringienses (Bt) bacteria produce a natural insecticide (kills insects). Widespread use of Bt has lead to Bt resistance among insects. Why is this occurring?
a) Individual insects that have mutations providing resistance to Bt can survive in the presence of Bt. The survivors pass this Bt resistance on to their offspring.
b) Bt-resistant insects increase in the population by chance. There are so many insects that some of them are resistant to each type of insecticide.
c) In the presence of Bt, individual insects evolve to become Bt resistant.
d) Natural selection causes insects to generate genes providing resistance to Bt.
** choose and justify your answer**

2. Get back with your groups.
You have 15 minutes to check in on your presentations. CHECK EACH OTHER.
You present tomorrow! Presentations are due to me electronically by 7:30am tomorrow.

3. Topic: Natural selection
Essential question: How do organisms change over time?

4. How do organisms change over time?
several different mechanisms can produce change in organisms over time
one of these mechanisms is natural selection
natural selection is the process whereby organisms that are more adapted to their environment are more likely to survive and reproduce

5. how does natural selection work?
individuals show variation in traits
these variations are passed from parents to offspring (they are heritable)
some individuals are more successful at surviving and reproducing than others
individuals with favorable variations are more likely to survive and reproduce

6. how does natural selection work?
individuals in this population of beetles
vary in their color
color is a heritable trait
some beetles are more likely to survive and reproduce than others
crows prefer to eat green beetles
brown beetles
specifically are more likely to survive and reproduce
they pass on their brown color to their offspring
over many generations, the population will consist of brown individuals
University of California Museum of Paleontology's Understanding Evolution (

7. important terminology: brown beetles are more “fit”
fitness is the ability of an individual to survive and reproduce in its environment
“survival of the fittest”

8. important terminology: brown color is “adaptive”
an adaptation is a trait or characteristic that increases the survival or reproduction of an individual relative to individuals without the trait

9. Galapagos finches: an example of natural selection in action
Rosemary and Peter Grant and colleagues performed studies of finches on Daphne Major over many decades
they have been able to witness natural selection in action

10. Galapagos finches
medium ground finch (Geospiza fortis) eats seeds by cracking them with its beak
the Grants measured bird size, beak size and what they were eating every year

11. there is variation in beak size in the population
beak size is correlated with size of seeds the finch collects and eats: bigger beaks, bigger seeds

12. beak size is heritable big beaked parents have babies with big beaks
small beaked parents have babies with small beaks

13. individual finches vary in their success at surviving and reproducing
severe drought in 1977 caused plants to produce very few seeds, many finches starved to death and did not reproduce

14. survival and reproduction was correlated with having a large beak
the most abundant seeds during the drought were large, hard seeds
large seeds of Tribulus cistoides

15. survival and reproduction was correlated with having a large beak
finches with large beaks were more likely to survive and reproduce

16. misconceptions about natural selection
an individual does not change in response to natural selection
the characteristics and make up of populations change in response to natural selection

17. misconceptions about natural selection
natural selection is not forward looking
there is no ideal end point to natural selection
natural selection is not “perfect”
organisms cannot be adapted to future environmental conditions

18. misconceptions about natural selection
selection does not act for the good of the species
if a trait increased the fitness of the group while reducing the individual’s fitness, it would strongly be selected against
e.g. alarm calls by monkeys that warn the group but draw attention to the caller, causing it to get eaten

19. ** choose and justify your answer**
Bacillus thuringienses (Bt) bacteria produce a natural insecticide. Widespread use of Bt has lead to Bt resistance among insects. Why is this occurring?
a) Individual insects that have mutations providing resistance to Bt can survive in the presence of Bt. The survivors pass this Bt resistance on to their offspring.
b) Bt-resistant insects increase in the population by chance. There are so many insects that some of them are resistant to each type of insecticide.
c) In the presence of Bt, individual insects evolve to become Bt resistant.
d) Natural selection causes insects to generate genes providing resistance to Bt.
** choose and justify your answer**

20. Do Now
Re-read your Natural selection notes from yesterday.
Highlight key terms and ideas
Write a summary at the bottom
*I will be coming around to stamp this today*

21. Your grade on presentation
20 points possible
15 points from presentation
above standard is extra credit
I will be filling out the rubric as you do your presentation
5 points from your peer evaluation rubric
number of points based on the distribution of work.
Equal distribution, everyone gets 5 points.
People who didn’t do their share get less than 5 points.
People who did no work get 0 points.

22. 2nd Presentations
Columbia:
Emory
Harvard
MIT
Northwestern (ppt – Antibiotic resistance solution)
Stanford (ppt – overprescription)
UCLA:

23. 3rd Presentations
UCLA
Stanford
Northwestern:
MIT
Harvard
Emory
Columbia

24. 6th Presentations
Columbia
UCLA
Harvard
Stanford
MIT
Emory:
Northwestern

25. Quiz tomorrow! Bacteria Antibiotics Adaptations Variation Fitness
Biotic potential (concepts, not math)
Natural selection
(after the quiz we will finish up the presentations)

26. Do Now What is the variation in this population?
Why are some mice white and some grey?
What is the selective pressure (what is causing the change in the population) in this example?