Thursday May 4, 2017 I can: Agenda Catalyst HW: IP: Resistance explain how evolution affects bacteria and pests Agenda (10) Catalyst (15) GN: Resistance (25) Eyes of Nye Video (10) Partner Answer Review (20) Class Answer Review (10) IP: Resistance (5) Exit Ticket Catalyst Where does all the variation in a population come from? How does natural selection affect a population over time? Natural selection is also called: What are the 4 requirements for evolution? What happens to populations as their surroundings change? HW: IP: Resistance

bacteria evolve especially rapidly because they reproduce quickly… Natural selection is everywhere! Case Study #1: Antibiotic Resistance bacteria evolve especially rapidly because they reproduce quickly… …and have developed resistance to antibiotics. Antibiotics are medicines used to treat bacterial infections. Resistance is when something stops working.

Evolution requires these four things (VSIT): Variation – differences between individuals in a species Selection – some individuals have greater fitness than others in the environment Inheritance – the traits that result in greater fitness can be passed on to offspring Time – many, many generations must pass Let’s see if we can explain antibiotic resistance in terms of the four requirements for evolution by natural selection.

Variation: A few mutated individuals in a population of bacteria have genes that allow them to destroy, inactivate, or eliminate antibiotics. They are protected from the antibiotics. MUTANT MUTANT 4

Selection: The mutated bacteria have greater fitness Selection: The mutated bacteria have greater fitness. They are more likely to survive after the antibiotic is taken. MUTANT MUTANT 5

Inheritance: The mutated bacteria reproduce more and pass on their resistance genes. Time: Over many generations, more bacteria become resistant until resistance is widespread. MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT 6

ANTIBIOTICS APPLIED AGAIN! Inheritance: The mutated bacteria reproduce more and pass on their resistance genes. Time: Over many generations, more bacteria become resistant. MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT ANTIBIOTICS APPLIED AGAIN! MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT 7

Time: Over many generations, more bacteria become resistant. Inheritance: The mutated bacteria reproduce more and pass on their resistance genes. Time: Over many generations, more bacteria become resistant. MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT MUTANT 8

Antibiotic resistance is caused by a variety of factors: over-prescription of antibiotics: doctors prescribe antibiotics for viral infections, even though antibiotics only work on bacteria overuse of antibiotics in the meat industry failure to finish medication: patients not finishing their entire prescription leads to some bacteria surviving

Got strep? Too bad, antibiotics don’t work! Why is it a problem? If you get sick with resistant bacteria, you can’t treat it with antibiotics Got strep? Too bad, antibiotics don’t work!

Methicillin-resistant staphylococcus aureus.

What can be done to prevent further resistance? Doctors can prescribe fewer antibiotics Patients can finish ALL their antibiotics

Case Study #2: Pesticide Resistance A pesticide is a substance used to kill insects. Pesticide resistance occurs when insects are no longer affected by pesticides.

Why is pesticide resistance a problem? crop damage

Why is pesticide resistance a problem? spreads disease

Evolution requires these four things (VSIT): Variation – differences between individuals in a species Selection – some individuals have greater fitness than others in the environment Inheritance – the traits that result in greater fitness can be passed on to offspring Time – many, many generations must pass Let’s see if we can explain pesticide resistance in terms of the four requirements for evolution by natural selection.

Variation: A few mutated individuals in a population of bedbugs have genes that make them unharmed by pesticides.

Variation: A few mutated individuals in a population of bedbugs have genes that make them unharmed by pesticides.

Selection: The mutated bed bugs have greater fitness Selection: The mutated bed bugs have greater fitness. They are more likely to survive after the pesticide is applied.

Inheritance: The mutated bed bugs reproduce more and pass on their resistance genes. Time: Over many generations, more bed bugs become resistant.

Inheritance: The mutated bed bugs reproduce more and pass on their resistance genes. Time: Over many generations, more bed bugs become resistant.

Inheritance: The mutated bed bugs reproduce more and pass on their resistance genes. Time: Over many generations, more bed bugs become resistant.

What can we do? Farmers can use fewer pesticides, or rotate the pesticides they do use. Consumers can buy organic (no pesticides).