Transcript trade-offs
Objectives 1.Use data (evidence) to make claims about variation, fitness, selection and evolution in populations. 2.Apply the general definition of Natural Selection and the concept of trade-offs to specific cases (e.g., guppies and antibiotic resistance in bacteria) Sex and Guppies http://www.pbs.org/wgbh/evolution/sex/guppy/gallery.html Trade-offs Initial population: Mostly drab LOW level of predation Time 1: Number of guppies: 227 Number of generations: 5 Number of weeks: 112 Time 2: Number of guppies: 232 Number of generations: 12 Number of weeks: 407 Trade-offs Initial population: Even mix HIGH level of predation Time 1: Number of guppies: 171 Number of generations: 4 Number of weeks: 57 Time 2: Number of guppies: 100 Number of generations: 7 Number of weeks: 203 Trade-offs What would happen if... Initial population: •EVEN mix of guppy coloration •MEDIUM level of predation? What would the population look like after 7 generations? Make a prediction. You can test your prediction at: http://www.pbs.org/wgbh/evolution/sex/guppy/low_bandwidth.html Trade-offs: define Each trait may have both costs and benefits. It is impossible for any population of organisms to evolve optimal solutions to all agents of selection at once. Antibiotic resistance • Do you use antibacterial soap? Why or why not? Discuss in your groups. Reading in Angel: Microbes: What They Do & How Antibiotics Change Them Maura Meade-Callahan CQ Mutation acts directly on …. A. B. C. D. E. DNA RNA Amino acids Protein Phenotype CQ Fitness is …. A. Absolute B. Relative Antibiotic Resistance in Bacteria: an experimental approach Antibiotic Resistance in Bacteria: an experimental approach 1. Redraw this model and label: a) Bacterial lawn b) Inhibition zone c) Discs of antibiotics 2. Label a point on the model where bacterial are likely most resistant to the antibiotic. Variation and Antibiotic Resistance 1. Do you think there is variation among these bacteria? Explain. Variation and Antibiotic Resistance 1. Do you think there is variation among these bacteria? Explain. 2. What is the origin of this variation? 3. Is the variation heritable? Fitness and Antibiotic Resistance 1. Does the environment vary across the Petri plate? Fitness and Antibiotic Resistance 1. Does the environment vary across the Petri plate? 2. Are these bacteria equally fit in all environments? Antibiotic resistance: Selection Describe this graph. What can you say about: 1.Variation? 2.Fitness? 3.Selection? Antibiotic Resistance: putting it all together Create a model that demonstrates the evolution of an antibioticresistant bacteria population. Label your arrows with processes! Start Key to figure: • Blue = antibiotic-sensitive bacteria • Orange = antibiotic-resistant bacteria • x = antibiotic End Antibiotic resistance • Has your opinion about antibacterial soap changed? Reading in Angel: Microbes: What They Do & How Antibiotics Change Them Maura Meade-Callahan