A small island is home to a unique population of land snails. This population was founded by 10
individuals that floated to the island on a log, and it has been isolated from the large mainland
population ever since. The mainland population has consistently had about 10,000 individuals in it
through time. The island population reached 1000 individuals after several generations, and then
stayed at this size through time.
A team of researchers compared the genetic variation of the mainland and the isolated island
populations for a few generations after colonization. Would a biologist agree (eens) or disagree
(oneens) with the following statements?
1. Genetic drift is more pronounced in the island population than the mainland population.
2. The biologists observed genetic drift but not evolution.
3. The island population likely has fewer alleles — that is versions of genes — than the
mainland population.
4. Some harmful traits may have become more common in the island population than the
mainland population.
After forty generations, biologists measured the genetic variation of the isolated island snail
population again. They concluded that the population of snails on the island had remained isolated
and that genetic drift had occurred. Would a biologist agree (eens) or disagree (oneens) with the
following statements about the processes that contributed, at least in part, to genetic drift in the
population of island snails?
5. The fact that snails needed to adjust to the environment contributed to genetic drift.
6. The fact that individuals that were best suited to the environment had a higher rate of
survival contributed to genetic drift.
7. Random survival of different individuals could not have contributed to genetic drift because
random processes are unpredictable.
8. The island population may have adapted to conditions on the island through genetic drift.
A biologist raised 100 populations of flies in a lab. At the beginning of the experiment, each
population had 16 flies: 8 with plain wings and 8 with striped wings. These 16 flies reproduced to
form the first generation of offspring. In each of the 100 populations, the biologist randomly chose 16
of the offspring as breeders for the next generation. She repeated this process for 20 generations. At
the end of the experiment, half of the populations contained only plain ‐winged flies, and the other
half contained only striped‐wing flies. Wing pattern is a genetically controlled trait that does not
affect how well flies survive or reproduce. Would a biologist agree (eens) or disagree (oneens) with
the following statements about the experimental results?
9. The experiment did not control for all the variables, so the environments were different
enough that natural selection contributed to the changes in the frequency of the two wing
types in these populations.
10. The small number of individuals reproducing each generation contributed to the rapid
changes in the frequency of the two wing types in these populations.
11. The populations were isolated from each other so genetic drift could not have caused the
results.
individuals that floated to the island on a log, and it has been isolated from the large mainland
population ever since. The mainland population has consistently had about 10,000 individuals in it
through time. The island population reached 1000 individuals after several generations, and then
stayed at this size through time.
A team of researchers compared the genetic variation of the mainland and the isolated island
populations for a few generations after colonization. Would a biologist agree (eens) or disagree
(oneens) with the following statements?
1. Genetic drift is more pronounced in the island population than the mainland population.
2. The biologists observed genetic drift but not evolution.
3. The island population likely has fewer alleles — that is versions of genes — than the
mainland population.
4. Some harmful traits may have become more common in the island population than the
mainland population.
After forty generations, biologists measured the genetic variation of the isolated island snail
population again. They concluded that the population of snails on the island had remained isolated
and that genetic drift had occurred. Would a biologist agree (eens) or disagree (oneens) with the
following statements about the processes that contributed, at least in part, to genetic drift in the
population of island snails?
5. The fact that snails needed to adjust to the environment contributed to genetic drift.
6. The fact that individuals that were best suited to the environment had a higher rate of
survival contributed to genetic drift.
7. Random survival of different individuals could not have contributed to genetic drift because
random processes are unpredictable.
8. The island population may have adapted to conditions on the island through genetic drift.
A biologist raised 100 populations of flies in a lab. At the beginning of the experiment, each
population had 16 flies: 8 with plain wings and 8 with striped wings. These 16 flies reproduced to
form the first generation of offspring. In each of the 100 populations, the biologist randomly chose 16
of the offspring as breeders for the next generation. She repeated this process for 20 generations. At
the end of the experiment, half of the populations contained only plain ‐winged flies, and the other
half contained only striped‐wing flies. Wing pattern is a genetically controlled trait that does not
affect how well flies survive or reproduce. Would a biologist agree (eens) or disagree (oneens) with
the following statements about the experimental results?
9. The experiment did not control for all the variables, so the environments were different
enough that natural selection contributed to the changes in the frequency of the two wing
types in these populations.
10. The small number of individuals reproducing each generation contributed to the rapid
changes in the frequency of the two wing types in these populations.
11. The populations were isolated from each other so genetic drift could not have caused the
results.
