Change in Precipitation
Ramon Pena
BIO101
February 14, 2011
Dr. Richard Steiner

Change in Precipitation
Introduction
This experiment will take course during a 300-year-time -period simulation. This experiment will consist of two islands, Darwin Island, Wallace Island and take only into account the bird population of these two islands. The parameter will stay the same, except for one variable; precipitation. I will record how the precipitation changes the beak size of the bird population and what other effects it has on them. My hypothesis is that if the amount of precipitation is changed in one of the island then there will be more food. If there is more food in one of the islands then I can assume that more birds have access to more food, thus requiring a bird’s beak to stay the same while the birds from the other island have an increase in beak size due to the fact that they have to scavenge more for their food.
Materials
For this experiment, I will use a windows-based desktop computer with a 24-inch monitor for better viewing of graphs and simulations. I will also use notebook for recording cross time period information. Within the computer, I will be using a Java-based tool simulation, named Evolution Lab that will run the experiment and demonstrate the results. This will be the most important material for this experiment.
Procedures
First, this experiment takes place on a computer simulation called Evolution Lab. The Evolution lab can be accessed through the University of Phoenix web portal for students and faculty members. Upon access to the simulation and starting up there is a button that can change the inputs of certain parameters, in this experiment, I will only change the amount of precipitation that falls on one of the islands. Upon changing the amount I can already see that there is a change in food.
The seed from the island that we are changing precipitation is Darwin Island. The amount of change is by two. Wallace Island will get 20.0 cm is precipitation and Darwin Island will get 40.0 cm in precipitation. The data will also be examined for multiple time periods; 100 years, 200 years and 300 years.
Data
The food change is as followed; the hard seed count from Wallace Island to Darwin Island decreased, from 64 percent down to 36 percent. The medium size seeds increased from 32 percent up to 48 percent. And the soft seed count increased as well from 4 percent to 16 percent.
The Changes here demonstrate how the hard seed count declined and went from a 1:1 ratio to 16:9 [ There are no sources in the current document. ] [ There are no sources in the current document. ] in hard seed count. The medium-size seed population saw in increase in a 3:2 ratio compared to Wallace Island. In the small-size seed population the ratio was 4:1; it quadrupled the amount of seeds in this category.
Visiting the date for the first 100 years shows an increase in beak size for both bird populations in both islands; however Wallace saw a bigger increase. Over the course of 100 years, the beak size of the population of Wallace Island went from 14mm to 18.34mm.
The population of Darwin Island only grew 16.8mm. Over the course of 200 years, the beak size of the Wallace Island birds has now grown to 22.2mm while the Darwin Island birds now have a beak size of 20.11mm. Over the course of 300 years, the beak size of the Darwin Island population has increased but not by much, now they have a beak size of 20.5mm average while those of Wallace island has increased to 24.11mm.
The graphs show that there are more birds with the average size beak than any other bird with a different beak size. The average being those numbers stated above.
Results
The results show that an increase in precipitation by twice as much in one island affect the animals, and the vegetation altogether. The seed population gained more soft seeds in the island and lost heavy seeds in the Darwin Island, the island that had more precipitation. Wallace Island, kept more of the heavy seeds and less of the soft seeds.
Darwin Island birds had an increase of beak size from 12mm to 20.5mm during a 300 year period. Wallace Island birds had a bigger increase in their beak size, from 12mm to 24.11 during the same time period.
The population of the Darwin Island birds dramatically increased in the first 200 years, while the bird population of Wallace Island only steadily increases for 300 years until reaching the same average of that of Darwin Island.
The data shows that the island with more heavy seed had a larger beak size increase during the 300 year time period. My hypothesis was off but what I do conclude is this; since it rains more in Darwin Island, there is more fresh and new food growing all the time. Birds in this island do not have to search for long and even less battle with the seed in other to eat it. In Wallace Island, There is a lack of rain, thus the vegetation grows a bit tougher. Since it is tougher, the birds have to fight more to get their food, requiring a bigger beak. The population in this island is more controlled, since those that do get their food, get to live, while on Darwin Island, every bird seem to procreate despite the lack of a longer beak.
Conclusion
With the help of a desktop computer and a big screen monitor, I was able to conclude that changing the precipitation between two identical islands can have a change in population, size of and growth rate of animals and vegetation. In this experiment we took only data from the bird population and some factors of vegetation to conclude that those birds that have less rain in their habitat do have a larger beak to ensure survival.

References
EvolutionLab, 2001. California State University and Benjamin Cummings.