Note: though the turtles have different colors, color is a random trait. You’ll usually see one color go to fixation.
First, look at the evolution of the population when mate choices are purely random. We can simulate this by setting lek-size to 1. Set carrying-capacity to 100, and the log-mutation-rate to -1 (which is pretty high), so there are a lot of mutations. Also, set genetic-linkage to 0, so that alleles are passed on to offspring independent of each other. Click setup and go. Stop it at about the 250 generation mark. Pay attention to any changes in the graphs.
5)How have the following changed?
- Preference for size
- Preference for turning bias
- Turning bias
- Size
- 6)Since the frequency of the various traits has changed (most notably, new preferences have emerged), this population has evolved. What factors affected the evolution of this population? How did these factors affect evolution in this population? (i.e. selection, mutation, genetic drift, migration.)
- Now let’s look at what happens if organisms have the opportunity to choose between different mates. Try setting the lek-size to 2 (the minimum, non-zero level of sexual selection). Click setup and go. Stop it at about the 250 generation mark. Pay attention to any changes in the graphs.
- 7)How has the following changed?
- Preference for size
- Preference for turning bias
- Size
- Turning bias 8)How does size or tuning bias affect the organism’s fitness in this population? 9)In a real population, what could prevent runaway selection from occurring? Let’s see what happens when sexual selection is more intense. Set lek-size to 10. Click setup and go. Stop it at about the 250 generation mark. 10)What did you see in this run of the simulation that was different from the previous one? List 3 things.
- We have been running the model with extremely high mutation rates (10% per generation). Let’s look at how things change when we lower the mutation rate. Leave lek-size at 10, Set log-mutation-rate to -2.7. Click setup and go. Stop it at about the 500 generation mark. Pay attention to any changes in the graphs. 11)Looking at the graph of Mating Preferences, what patterns do you observe in how preferences changed? 12)What do you notice about the variance in the turning bias and size traits (i.e. the range in sizes/turning biases present) compared to the simulations with a higher mutation rate? 13)Why did lowering the mutation rate affect the results?
- Let’s see what else can happen. Click setup and go again. Stop it at about the 500 generation mark and record what you saw. Do this until you get a different result than before. 14)What was the result and how was it different? List 3 things that you noticed were different.
- Here you will report the results of experiments that test how population size, mutation rate, generation time, and heritability affects the rate of evolution (i.e. the time it takes to reach a fertility of 2).First, set up a control experiment with the following parameters.carrying-capacity to 100log-mutation-rate to -1generation-time to 3heritability to 0.5Maximum-Fertility-Change to 0.2Click setup and run-experiment. Run the experiment 5 times. 19) How many “generations” (which in the output are more equivalent to years) does it take to evolve an average fertility rate of 2 (where the simulation stops)?
- Change the carrying capacity, run 5 times
- 20) What did you change it to?
- 21)How did your results change compared to the control? Why did this change in carrying capacity generate these results?
- Reset to control values, and change the mutation rate, run 5 timesNote: the higher the negative number, the lower the mutation rate. 0 is the highest mutation rate. 22)What did you change it to? 23)How did your results change compared to the control? Why did changing the mutation rate lead to these results?
