EEES 2160- Biodiversity
Spring 2006
Week 2. SIMULATING NATURAL SELECTION
Items of Special Attention
1. Chart your data from Figure 3 on the main lab whiteboard when finished, so to share and
compare results with your lab mates. Record the final collective graph. Observations about these
compiled data will be part of your lab report!
2. Observing live specimens in lab, note the extent of variation among individuals from a single
population of a species, and do so for both species selected for uniformity (commercial crop
cultivars of corn & pepper), compared to wild species (various grasses, agave, cactus, lambs
quarters, etc.).
3. For next week, week 3 lab- POPULATION GENETICS, you will need to research and
record the blood types of your relatives, as found in Table 2 of the Lab Manual.
Objectives for Week 2 Simulating Natural Selection
1. Use simulation method to understand the process of natural selection.
2. Have a better understanding of how natural selection can result in a change in the genetic
make-up of a population.
Questions to be answered in your lab report:
1. Did the mean camouflage and visual acuity increase or decrease? By how much?
2. Did population size change for either prey or predator? Was there any pattern or trend to the
changes in the size of the two populations? What would you expect to happen in nature?
3. Compare the initial and final frequency distributions in Figure 3. Did the variability of the two
populations change? By how much? (Hint: an approximate measure of variability is the range of
scores for each population.)
4. Draw and include graphs to show how the mean scores, population sizes, and frequency
distributions changed through time. Each graph should show two lines (1 = predator, 1 = prey).
5. Were results for your group always the same as results from other groups? Speculate as to
why or why not. Implications of this similarity or difference for evolution by natural selection?
5. You probably noticed that there is an element of chance in this simulation. Explain.
6. If you increased the initial size of each population to 1000, would this increase or decrease the
importance of chance events on the final outcome? Explain.
7. How did the extent of variation among individuals of a species differ among the different
species in the lab (e.g., for commercial species compared to wild species)?