Item SP001001: If individuals from two populations of fish (cichlids) cannot reproduce with each other, that is evidence that they are two different species.
Cichlids are fish that live in freshwater lakes. There are over a thousand different species of cichlids that differ in size, color, habitat, and diet. Which piece of evidence might scientists use to determine that two populations of cichlids are from different species?
- The two populations have a common ancestor.
- One population eats algae and the other population eats snails.
- Individuals from the two populations cannot reproduce with each other.
- One population lives at the bottom of the lake and the other lives near the surface.
Pre-Test
Answer Choice |
Overall |
Grades |
Gender |
Primary Language |
||||
|---|---|---|---|---|---|---|---|---|
| n = 2269 |
6–8 n = 91 |
9–12 n = 2013 |
Male n = 963 |
Female n = 1143 |
English n = 2055 |
Other n = 63 |
||
| A. | The two populations have a common ancestor. | 15% | 9% | 15% | 15% | 15% | 15% | 11% |
| B. | One population eats algae and the other population eats snails. | 17% | 19% | 17% | 19% | 16% | 18% | 13% |
| C. | Individuals from the two populations cannot reproduce with each other. | 44% | 45% | 45% | 47% | 43% | 44% | 48% |
| D. | One population lives at the bottom of the lake and the other lives near the surface. | 23% | 27% | 23% | 19% | 26% | 23% | 29% |
Post-Test (Control)
Answer Choice |
Overall |
Grades |
Gender |
Primary Language |
||||
|---|---|---|---|---|---|---|---|---|
| n = 1104 |
6–8 n = 70 |
9–12 n = 901 |
Male n = 434 |
Female n = 555 |
English n = 949 |
Other n = 33 |
||
| A. | The two populations have a common ancestor. | 11% | 16% | 11% | 11% | 11% | 11% | 3% |
| B. | One population eats algae and the other population eats snails. | 9% | 6% | 10% | 11% | 8% | 10% | 18% |
| C. | Individuals from the two populations cannot reproduce with each other. | 66% | 73% | 65% | 69% | 63% | 66% | 61% |
| D. | One population lives at the bottom of the lake and the other lives near the surface. | 14% | 6% | 14% | 9% | 17% | 13% | 18% |
Post-Test (Treatment)
Answer Choice |
Overall |
Grades |
Gender |
Primary Language |
||||
|---|---|---|---|---|---|---|---|---|
| n = 1165 |
6–8 n = 18 |
9–12 n = 1059 |
Male n = 535 |
Female n = 571 |
English n = 1055 |
Other n = 33 |
||
| A. | The two populations have a common ancestor. | 8% | 11% | 8% | 9% | 7% | 8% | 3% |
| B. | One population eats algae and the other population eats snails. | 8% | 6% | 8% | 9% | 8% | 8% | 12% |
| C. | Individuals from the two populations cannot reproduce with each other. | 76% | 78% | 75% | 74% | 77% | 75% | 79% |
| D. | One population lives at the bottom of the lake and the other lives near the surface. | 8% | 6% | 8% | 8% | 8% | 8% | 6% |