Evolution Lab
BIO/101
Pooja Thakur
7-23-12

Evolution Resulting From Natural Selection

INTRODUCTION The Evolution Lab simulates environmental situations to determine effects on evolution over periods of time. This lab experiments with the evolution of finches on two different islands over 100, 200, and 300 years. By manipulating parameters that influence natural selection, the effects that natural selection have on the evolution process can be studied.

HYPOTHESES • The size of the island will influence the population. • The amount of precipitation will influence beak size. • Variances in beak size will influence beak size.

MATERIALS The materials needed for this experiment consist of a computer and access to the Evolution Lab on the University of Phoenix student website. In the Evolution Lab there are two islands, Darwin Island and Wallace Island. There are seven variables that can be changed to run many different experiments on both islands. The variables are beak size, variance of beak size, heritability, clutch size, island size, population, and precipitation.

METHODS In all of the experiments Darwin Island was used as the control group and Wallace Island was the experimental group. So, in each test, the variables for Wallace Island were altered and the variables for Darwin Island were left alone. The first experiment was to determine whether or not the size of the island affected the population. To do this, the only variable that needed to be changed was island size. Darwin Island was left at 0.5 km and Wallace Island was changed to 1.0 km. The experiment was run over 300 years then the data was collected. The second step was to test beak size in relation to the amount of precipitation each island received. The only variable that was changed was precipitation for Wallace Island. The amount of precipitation was changed from 20 cm to 40 cm, double that of Darwin Island. Then the data was collected after revisiting in 300 years. Then to test if variances in beak sizes from bird to bird influences the evolution of beak size, the variance on Wallace Island was changed from 1 mm to 2 mm. This test was also run for 300 years then the data was collected.

DATA Test 1
|Parameter |Darwin Island |Wallace Island |
|Initial Beak Size |12 mm |12 mm |
|Heritability |0.7 |0.7 |
|Variance |1 |1 |
|Clutch Size |10 eggs |10 eggs |
|Precipitation |20 cm |20 cm |
|Population |200 birds |200 birds |
|Island Size |0.5 km |1 km |
| |Results | |
|Year |Darwin Island |Wallace Island |
|2096 |578 |1107 |
|2196 |632 |1236 |
|2296 |689 |1458 |

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DATA Test 2
|Parameter |Darwin Island |Wallace Island |
|Initial Beak Size |12 mm |12 mm |
|Heritability |0.7 |0.7 |
|Variance |1 |1 |
|Clutch Size |10 eggs |10 eggs |
|Precipitation |20 cm |40 cm |
|Population |200 birds |200 birds |
|Island Size |0.5 km |0.5 km |
| |Results | |
|Year |Darwin Island |Wallace Island |
|2096 |18.79 mm |16.38 mm |
|2196 |22.38 mm |19.64 mm |
|2296 |25.27 mm |20.78 mm |

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DATA Test 3
|Parameter |Darwin Island |Wallace Island |
|Initial Beak Size |12 mm |12 mm |
|Heritability |0.7 |0.7 |
|Variance |1 |2 |
|Clutch Size |10 eggs |10 eggs |
|Precipitation |20 cm |20 cm |
|Population |200 birds |200 birds |
|Island Size |0.5 km |0.5 km |
| |Results | |
|Year |Darwin Island |Wallace Island |
|2096 |16.82 mm |21.39 mm |
|2196 |20.87 mm |28.4 mm |
|2296 |24.7 mm |29.69 mm |

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DISCUSSION In the first test, the size of the island was very influential on the population growth. As shown in the table above, Darwin Island capped out at 689 birds and Wallace Island ended up with 1458 birds. Wallace Island was twice as big as Darwin Island and was able to sustain twice the population. In the second test, Wallace Island had twice the precipitation as Darwin Island did, allowing a more diverse food source than Darwin Island. As a result, beak size on Darwin Island steadily increased over the years at a rate greater than that of Wallace Island. After 300 years, the beak size on Darwin Island was 25.27 mm compared to 20.78 mm on Wallace Island, thus confirming that precipitation has great influence on the evolution of beak size. Finally, in test three, the variance in beak size from bird to bird was increased on Wallace Island. This resulted in a dramatic increase in beak size for the first 200 years, but planed out after that. After 100 years the control group beak size increased to 16.82 mm, whereas Wallace Island beak size increased to 21.39 mm. At the end of the study, Darwin Island beak size was 24.7 mm and Wallace Island beak size was 29.69 mm, substantiating the theory that variance in beak size affects the evolution of beak size.

CONCLUSION This experiment proves that simple factors can cause big changes over long periods of time. A creature’s ability to adapt to its environment is detrimental to the survival of their species. Limited resources and crowded environments create competition for inhabitants and those who cannot adapt and overcome die out. The victors pass on their winning traits to their successors and, over time, natural selection turns into evolution.

References

1. Evolution Lab (2011) Evolution Lab. http://www.biologylabsonline.com/axia/EvolutionLab/evlab.php.