January 19th, 2017

Stickleback Fish Lab

The Mystery behind the Stickleback Fish

Purpose:

The purpose of this lab was to determine if the Spine On gene was dominant or if the Spine Off gene was the dominant gene.

Hypothesis:

The Spine On gene was hypothesized to be the dominant gene because of results of a specific experimentdone on the fish. To determine if Stickleback fish that had not had a spine for decades could still develop a spine, the Spine On gene was inserted into the fish. After a few years, the experiment finally was successful and the fish began to develop a spine.

Predicted Results:

If the hypothesis is true and Spine On gene is the dominant gene, the first generation of Stickleback Fish will all have the Spine On gene. Afterwards when crosscutting the offspring of the first generation, it is predicted that 75% of the fish will have the spine and 25% will not.

Let the Spine On Gene = B (Homozygous dominant)

Let the Spine Off Gene =b (Homozygous recessive) BB x bb

Figure 1: F1 Generation predicted results

b / b
B / Bb / Bb
B / Bb / Bb

Genotypic Ratio= 100% Bb

Phenotypic Ratio = Spine On : Spine Off

4 : 0

100% Spine On Gene

When crossed, 100% of the Stickleback fish are heterozygous:

Figure 2: F2 Generation predicted results Bb x Bb

B / b
B / BB / Bb
b / Bb / bb

Genotypic Ratio: AA: Aa: aa

1 : 2 : 1

Phenotypic Ratio: Spine On : Spine Off

3 : 1

Spine On Gene: 1 Homozygous and 2 Heterozygous Dominant

Spine Off Gene: 1 Homozygous Recessive

Results:

Figure 3: Reviewing the total results of the F1 and F2 generations

Fish Generation and Number / Was it developing a spine? / Fish Generation and Number / Was it Developing a spine? / Fish Generation and Number / Was it Developing a spine?
F11 / Yes / F24 / Yes / F223 / Yes
F12 / Yes / F25 / No / F224 / Yes
F13 / Yes / F26 / Yes / F225 / Yes
F14 / Yes / F27 / No / F226 / Yes
F15 / Yes / F28 / Yes / F227 / Yes
F16 / Yes / F29 / Yes / F228 / Yes
F17 / Yes / F210 / Yes / F229 / Yes
F18 / Yes / F211 / Yes / F230 / Yes
F19 / Yes / F212 / Yes / F231 / Yes
F110 / Yes / F213 / Yes / F232 / Yes
F111 / Yes / F214 / Yes / F233 / No
F112 / Yes / F215 / Yes / F234 / Yes
F113 / Yes / F216 / Yes / F235 / No
F114 / Yes / F217 / Yes / F236 / Yes
F115 / Yes / F218 / Yes / F237 / No
F116 / Yes / F219 / Yes / F238 / Yes
F21 / No / F220 / Yes / F239 / No
F22 / No / F221 / Yes / F240 / Yes
F23 / No / F222 / Yes / Total Number of Spines / 47
The information in this Table illustrates the results of two experiments done on Generations F1 and F2. The table lists each fish by number and states whether it had a spine after the experiment. These results were achieved by crosscutting the first generation of true breeding Stickleback fish of fish that had a spine with fish that did not. Subsequently, the offspring of the first generation are crosscut and the second generation is created.

Summary:

In total, there are 47 fish that possess the Spine On gene and 9 fish that possess the Spine Off Gene. Every single fish from the first generation (16 fish total) and 31 fish from the second generation (40 fish total) had spines. The remaining 9 fish with the Spine Off Gene belong to the second generation. By percentage this means that 78% of the second generation has the Spine On gene and 22% have the Spine Off gene.

Conclusion:

Thus, the proposed hypothesis was proved to correct and the Spine On gene was proven to be the dominant gene. When comparing the predicted results with the actual results, the first generation predictions were correct. The predictions for the second generations were that 75% of the fish would have spines and 25% would not. However the actual results showed that 78% of the fish had and spine and 22% did not, furthermore proving that the Spine On gene is the dominant gene.

Evaluation Form

Item / Mark
Title / /1
Purpose / /2
Hypothesis / /2
Predicted Results
Letters used to denote alleles are defined
Crosses clearly indicate which generation is being predicted
Crosses clearly indicate the parents in the cross
Correct alleles for gametes in Punnett Square
Correct genotype for offspring in Punnett Square
Correct Genotype Ratios given and effectively communicated
Correct Phenotype Ratios given and effectively communicated
/ /5
Results
Data effectively summarized in a written paragraph
Detailed data effectively communicated in Table
Appropriate titles on data tables
Tables numbered
Appropriate Legends on all tables
Minimal interpretation included in results
/ /6
Conclusion / /2

*The effective use of technical terminology in this lab will be evaluated.