Download 2B Doc #2 Natural Selection New

2B Doc #2 : Natural Selection
Name:________________________________ Period: _____
Essential Questions:
1. Who is Charles Darwin? How did he formulate the Theory of Natural Selection?
2. What are the four postulates of natural selection?
Video: “What causes antibiotic resistance” by Ken Wu (Youtube, TedED)
What are some of the benefits of having bacteria in our body?
What types of medicines can fight bacteria that are harmful to us?
How can different bacteria prevent the medicine from working?
What do we do as humans to increase the chances that the bacteria will win over the medicine?
Darwin’s Four Postulates of Natural Selection:
1. Organisms produce more offspring than can survive.
Examples of why offspring die before they can reproduce:
2. Variations occur within a population of organisms.
Example Trait:
Examples of traits and their variations:
Variation 1
Variation 2
Variation 3
Height in Humans
Body Hair
Work Ethic
3. Some variations within a population are beneficial. (Remember what makes an adaptation beneficial)
In order to determine if an adaptation is beneficial we have to put an organism in an environment to judge
it’s adaptation:
Example Trait:
Variation 1
Which variation is beneficial?
Variation 2
Variation 3
Environment: Environmental Disaster; force to live in caves and underground.
Height in Humans
Environment: Nuclear winter; sun is blocked out and the Earth is colder
Body Hair
Environment: Pandemic kills 90% of world and all technology is lost.
Work Ethic
4. Overtime, populations will consist of more individuals with the beneficial variation (adaptation).
Example Trait:
What trait will make up more of the population?
Variation 1
Variation 2
Variation 3
Environment: Environmental Disaster; force to live in caves and underground.
Which variation will be most common in the population several hundred years in the future if
the environmental pressure continues?
Height in Humans
Environment: Nuclear winter; sun is blocked out and the Earth is colder Which variation will be
most common in the population several hundred years in the future if the environmental
pressure continues?
Body Hair
Environment: Pandemic kills 90% of world and all technology is lost. Which variation will be
most common in the population several hundred years in the future if the environmental
pressure continues?
Work Ethic
Now we are going to apply Darwin’s Four Postulates to Antibiotic Resistance. Here are the four steps:
1. More offspring are produced than can survive.
2. Variations exist within a population.
3. Beneficial variations help an organism survive and reproduce.
4. Over time, more individuals will have the beneficial trait.
Yikes, you have a bacterial infection in your body! Let’s show the process of what happens when the
bacteria reproduce to cause the infection and how antibiotics work:
Before Antibiotics:
Introduction of Antibiotics:
Antibiotics over Time:
(Full Course)
(Stop Early)
After taking antibiotics:
After taking antibiotics: