Assignment: Natural Selection

ANSWER SHEET

Presimulation Question

Q1. Describe the process of natural selection in your own words. You can answer this either as a paragraph or in a list format. Include all the necessary components and how these relate to each other, leading to change over time.

How species adapt to their environment to survive. Organisms better adapted to their environment are more likely to survive and reproduce than those less adapted. Natural selection results in Evolution, which is the changes in allele frequency. It is the basic mechanism of evolution. First step in natural selection is variation in traits of the organism, next will be a differential reproduction. An example of this is if there are brown and green beetles and birds like the color of the green beetles, they will eat and kill those, leaving the brown beetles to survive and thrive. The next step is heredity; the brown beetles will have brown babies and they survive.

Natural Selection Bunny Simulation

Experiment 1

Q2. Prediction: Read through the experiment. Then in the space below hypothesize how the recessive mutation for brown fur will affect the evolution of this bunny population over the next 10 generations. When writing hypotheses, scientists use a common format: If ——-, then ——-. Example: If a plant receives fertilizer, then it will grow bigger. In this case, I would also like you to give a reason for your hypothesis (because…).

If the brown fur is a recessive trait then it will appear less than the white. Recessive does not mean that the trait will disappear through the span of 10 generations but the numbers of brown bunnies will slowly increase. The ratio of white bunnies to brown bunnies will probably be 100:1. This depends on how often the bunnies reproduce but if brown bunnies reproduce with other brown bunnies there will be more but either way the dominant trait, which is white fur, will far outnumber the brown bunnies.

Data table 1	Graphical Data			Percentage calculations
Generation number	Number of Brown	Number of White	Total	% Brown Rabbits	% White Rabbits
2	0	6	6	0	100
4	2	52	54	3.7	96.3
6	6	485	491	1.22	98.8

Analysis:

Calculate the percentage of each color of rabbit using the following method:

% Brown rabbit = (Brown rabbits / Total rabbits) X 100

% White rabbit = 100% – % brown rabbits.

Q3. Briefly explain how the brown fur mutation affected the allele frequency of the population. Besure to use your data in this explanation.

Q4. Does the data in the table above support the hypothesis for this experiment?  Be sure to use your data in an explanation of why the data does or does not support your hypothesis.

The data supports my hypothesis; the white bunnies far outnumbered the brown fur bunnies.  The ratio was a bit off but nonetheless what I said was still correct.

Experiment 2

Q5. Prediction: Read through the experiment. Then in the space below hypothesize how the dominant mutation for long teeth will affect the evolution of this bunny population over the next 10 generations. (Remember…if, then, because statements)

If long teeth are dominant the number of long teeth rabbits will outnumber the normal teeth rabbits. Because of this mutation at the end of the 10 years the number of dominates rabbits should surpass the normal teeth rabbits.

Data table 2	Graphical Data			Percentage calculations
Generation number	Number of Normal teeth	Number of Long teeth	Total	% Normal Tooth Rabbits	% Long Tooth Rabbits
2	6	0	6	100	0
4 6 6	27 390	10 100	37 490	73 79.6	27 20.4
7
10

 

Calculate the percentage of each tooth type using the following method:

 

                   % Long tooth rabbit = (Long tooth rabbits / Total rabbits) X 100

                   % Normal tooth rabbit = 100% – % Long tooth rabbits.

Q6. Briefly explain how this change in DNA affected the allele frequency of the population. Besure to use your data in this explanation.

Q7. Does the data in the table above support the hypothesis for this experiment?  Be sure to use your data in an explanation of why the data does or does not support your hypothesis.

My hypothesis was wrong; the number of normal teeth rabbits still surpassed the dominant long teeth rabbit. Maybe not 10 years but after 20 years or more the number of long teeth rabbits will surpass the normal teeth rabbits.

Experiment 3

Q8. Prediction: Read through the experiment. Then in the space below hypothesize how the dominant mutation for a long tail will affect the evolution of this bunny population over the next 10 generations. (Remember…if, then, because statements)

If the dominant trait is long tail then there should be less of the long rabbits than the short tails. In my previous experiment the number of my dominate rabbits were less than the less dominate rabbit, so im assuming in will be the same in this one.

Data table 3	Graphical Data			Percentage calculations
Generation number	Number of Short Tail	Number of Long Tail	Total	% Short Tail Rabbits	% Long tail Rabbits
2	0	0	0	0	0
4	44	10	54	81.48	15.52
6	380	103	483	78.67	21.33
7	1160	320	1480	78.37	21.63

Calculate the percentage of each tail type using the following method:

% Short tail rabbit = (Short tail rabbits / Total rabbits) X 100

% Long tail rabbit = 100% – % brown rabbits.

Q9. Briefly explain how this change in DNA affected the allele frequency of the population.  Be sure to use your data in this explanation.

Q10. Does the data in the table above support the hypothesis for this experiment?  Be sure to use your data in an explanation of why the data does or does not support your hypothesis.

My data supported my hypothesis, I was correct in that the dominate long tail rabbits will be less than the short tail rabbits 

Discussion Questions

Use your data, your knowledge of evolution, and genetics to answer the questions that follow.

Q11.Given the current definition of evolution being a change in allele frequency over time, did any of the mutations above fail to cause the population to evolve?  If so which one?  Use your data to explain how you know.

Q12. Predict what would have happened in simulation 1 if you had switched the environment from equator to arctic. Do you think the brown rabbits could have been completely bred out of the population like the white ones may have been in simulation 1?  Why or Why not?

Q13. In simulation three there should have been very little change in the percentage of each type of rabbit.  Why did the allele frequencies not change as drastically in this simulation as they did in the other two?

Q14. Compare your data from simulation 1 and simulation 2.  In simulation 1 the mutation was recessive; in simulation 2 the mutation was dominant.  What was different about how these two populations evolved after the mutation?  Did being the dominant form of the trait insure that it would be selected for?

Q15. The mutations you made were in reality small changes in the DNA.  Briefly explain how a small change in DNA can cause such a huge evolutionary shift within a population.