Adaptation and Context-dependent fitness in Avida-ED

1. Adaptation and Context-dependent fitness in Avida-ED • Maren Friesen & Andy Jarosz • 06 June 2015

2. Courses 162: second biology course 445: upper-level evolution Juniors & seniors 100 students 2 x 50 min lectures + 50 min recitation (25 students each) Tier 2 writing course Quantitative skills (algebraic problem-solving)  many students (still) really struggle • Freshman & sophomores • 120 students • 2 x 90min lectures/wk • Scientific reasoning & writing • Quantitative skills (algebraic problem-solving)  many students really struggle

3. Why do organisms "match" their environments?

4. What will happen when environments change? http://www.npr.org/2013/09/08/220188619/climate-change-leaves-hares-wearing-the-wrong-colors

5. Learning Goals • Concept: Fitness is context-dependent • Objectives: • Make predictions about how organisms that have evolved in one environment will perform in another environment • Explain how some mutations can be adaptive under all environments while others can only be adaptive under some environments

6. Avida-ED • 3 types of environments • 1000 cycles with no rewards • 1000 cycles with only "nan" • 1000 cycles with only "not" • Save 3 Avidian genotypes per selection regime (2% mutation rate) • Measure fitness under all environments, plus "nan & not" [novel environment]

7. Predict which genotype(s) will be most fit in each environment

8. Measuring Fitness start with ancestor and 9 evolved genotypes turn mutation off, update for 50 cycles Ancestor no reward nanose notose

9. Measuring Fitness start with ancestor and 9 evolved genotypes turn mutation off, update for 50 cycles Ancestor no reward nanose notose

10. Measuring Fitness start with ancestor and 9 evolved genotypes turn mutation off, update for 50 cycles Ancestor no reward nanose notose

11. Fitness Worksheet Environment they evolved in Environment fitness is measured in Ancestor

12. no reward not ancestor no reward nanose norose not & nan nan

13. Questions • What happened to make all the evolved genotypes have higher fitness than the ancestor in the no-reward environment? • Explain why the fitness values are different in the "not" environment compared to the "nan" environment. • What do you predict will happen if a "not"-adapted avidian is competed against a "nan"-adapted avidian in a not environment? What about if they compete in a nan environment? What about if both not & nan are available?

14. no reward not ancestor no reward nanose norose not & nan nan

15. Fitness Worksheet (M) Environment they evolved in Environment fitness is measured in Ancestor

16. Fitness Worksheet (A) 2000 cycles @ 0.5% Environment they evolved in Environment fitness is measured in Ancestor Discuss!

17. Assessment: Exam Q • Case study: Antibiotic-resistant bacteria. Fitness is measured in the presence and absence of the antibiotic for two different strains • Strain 1: 0.52 with antibiotic; 0.52 without • Strain 2: 0.64 with antibiotic; 0.45 without • a) Predict the evolutionary outcome of a population containing both genotypes of bacteria (1) in the presence of the antibiotic (2) in the absence of the antibiotic. • b) Explain why strain 1 and strain 2 have different fitnesses. • c) What do you hypothesize about the environment that each strain evolved in?