Evolution
Evolution and Natural Selection
New species can arise when barriers to reproduction within a population lead to two populations that over time e…
Item SP006002: When two populations of organisms interbreed, alleles from one will be found in the other (trout in Lakes Unknown, Mystery, and Forgotten).
A hundred years ago, a network of streams connected three lakes: Lake Unknown, Lake Mystery, and Lake Forgotten. These streams allowed trout to travel freely between the three lakes and interbreed.
Due to environmental changes, the streams connecting the lakes dried up, so trout in each lake can no longer breed with trout from the other two lakes. Biologists are interested in how this change has affected the frequencies of different alleles of Gene Z. The chart below shows the allele frequencies of Gene Z in the three populations.
Suppose that several floods created new streams that run between the three lakes. Which of the following pieces of evidence would suggest that trout populations between the three lakes are interbreeding again?
- Allele 3 disappears from Lake Unknown
- Allele 1 disappears from all three lakes.
- Allele 2 disappears from all three lakes.
- Allele 3 appears in Lake Mystery and Lake Forgotten
Pre-Test
Answer Choice |
Overall |
Grades |
Gender |
Primary Language |
||||
|---|---|---|---|---|---|---|---|---|
| n = 559 |
6–8 n = 23 |
9–12 n = 499 |
Male n = 221 |
Female n = 300 |
English n = 516 |
Other n = 13 |
||
| A. | Allele 3 disappears from Lake Unknown | 22% | 17% | 23% | 19% | 25% | 22% | 15% |
| B. | Allele 1 disappears from all three lakes. | 11% | 9% | 12% | 13% | 10% | 11% | 23% |
| C. | Allele 2 disappears from all three lakes. | 9% | 26% | 8% | 10% | 10% | 9% | 8% |
| D. | Allele 3 appears in Lake Mystery and Lake Forgotten | 57% | 48% | 57% | 58% | 56% | 57% | 54% |
Post-Test (Control)
Answer Choice |
Overall |
Grades |
Gender |
Primary Language |
||||
|---|---|---|---|---|---|---|---|---|
| n = 281 |
6–8 n = 18 |
9–12 n = 229 |
Male n = 109 |
Female n = 135 |
English n = 243 |
Other n = 9 |
||
| A. | Allele 3 disappears from Lake Unknown | 26% | 44% | 26% | 22% | 29% | 28% | 0% |
| B. | Allele 1 disappears from all three lakes. | 9% | 6% | 7% | 9% | 7% | 7% | 22% |
| C. | Allele 2 disappears from all three lakes. | 7% | 6% | 7% | 6% | 6% | 6% | 11% |
| D. | Allele 3 appears in Lake Mystery and Lake Forgotten | 57% | 44% | 60% | 63% | 59% | 59% | 67% |
Post-Test (Treatment)
Answer Choice |
Overall |
Grades |
Gender |
Primary Language |
||||
|---|---|---|---|---|---|---|---|---|
| n = 305 |
6–8 n = 3 |
9–12 n = 280 |
Male n = 139 |
Female n = 150 |
English n = 276 |
Other n = 8 |
||
| A. | Allele 3 disappears from Lake Unknown | 25% | 33% | 26% | 31% | 21% | 26% | 25% |
| B. | Allele 1 disappears from all three lakes. | 5% | 0% | 5% | 4% | 6% | 5% | 0% |
| C. | Allele 2 disappears from all three lakes. | 5% | 0% | 4% | 4% | 5% | 4% | 13% |
| D. | Allele 3 appears in Lake Mystery and Lake Forgotten | 65% | 67% | 65% | 61% | 68% | 65% | 63% |