Mastering Biology Chapter 22 HW
Charles Darwin _____. - answer proposed natural selection as the mechanism of
evolution
*Although Wallace submitted his work for publication first, Darwin's work was known to
have pre-dated Wallace's work and was much more detailed; therefore, Darwin was
given credit for the theory.
Why did dark-colored rock pocket mice first appear in a population of light-colored rock
pocket mice? - answer They have a genetic mutation that affects their fur color.
*The rock pocket mice that Dr. Nachman catches in the film have a mutation in a gene
that leads to the dark fur color.
Why do dark-colored rock pocket mice on dark lava flows have white bellies? - answer
There is no selection for dark bellies by visual predators.
*The color of a rock pocket mouse's belly is not visible to a predator and therefore is not
under strong selection pressure.
Mutations are always __________. - answera change in an individual's DNA
*Mutations are rare genetic changes that can be neutral, beneficial, or detrimental
depending on an individual's circumstances. A dark-color fur mutation is good for a rock
pocket mouse living on black lava and bad for one living in the sandy desert.
When dark-colored fur gives mice a 1% competitive advantage and 1% of the
population begins with dark fur, in about 1000 years, 95% of the population will have
dark fur. Which of the following statements is true? - answerIf dark-colored rock pocket
mice had a competitive advantage of 0.1%, it would take longer for 95% of the
population to have dark fur.
*A small evolutionary advantage can lead to large changes in a population. The larger
the advantage, the faster the changes occur.
What does Dr. Carroll mean when he says, "while mutation is random, natural selection
is not"? - answer- Mutations for advantageous traits are more likely to be passed on to
the next generation.
- Natural selection favors some mutations.
- Natural selection acts on traits.
, *Natural selection can only work on variation existing in a population. Mutation creates
variation randomly. Natural selection is not random; by determining which traits are
passed to the next generation, it can shape populations.
In the lab, Nachman examined dark mice from two different populations living hundreds
of miles apart. The mice looked nearly identical. Their dark color was caused by two
different genes. What does this tell you? - answer- Under very similar conditions, natural
selection can favor very similar adaptations.
- There are at least two genes involved in creating dark mouse fur.
- Two completely different mutations in two separate genes can generate the same
phenotype.
- Dark fur color evolved independently on each lava flow.
From his observations of organisms in the Galapagos islands, Darwin reasoned that
_____. - answerorganisms had adapted to new environments, giving rise to new
species
*Darwin reasoned that natural selection had increased the match between the
organisms and their environment.
This experiment is an example of hypothesis-based science.
What question did the researchers ask? - answerCan predation result in selection for
color patterns in guppies?
*Researchers transplanted guppies from pools containing pike-cichlid fish (intense
guppy predators) to pools containing killifish (less active predators that prey mainly on
juvenile guppies). They then determined whether color patterns in the transplanted
population changed over time.
What was the researchers' main hypothesis? - answerPredation results in selection for
more drab color patterns in guppies.
*Researchers hypothesized that predation should result in selection for more drab
colors in guppies because guppies with bright colors are more conspicuous to
predators.
Researchers further hypothesized that if predation pressure is reduced, drab coloration
would become less beneficial (since females prefer brightly colored mates). Based on
this hypothesis, what prediction did the researchers test in this experiment? -
answerWhen guppies with drab colors are transferred to a pool with only killifish, the
transplanted population will evolve brighter colors than the original source population.
*In pools with only killifish, predation would not counteract selection pressure resulting
from female guppies' preference for brightly colored males. As a result, the guppies
should evolve to be more brightly colored than the source population.
Charles Darwin _____. - answer proposed natural selection as the mechanism of
evolution
*Although Wallace submitted his work for publication first, Darwin's work was known to
have pre-dated Wallace's work and was much more detailed; therefore, Darwin was
given credit for the theory.
Why did dark-colored rock pocket mice first appear in a population of light-colored rock
pocket mice? - answer They have a genetic mutation that affects their fur color.
*The rock pocket mice that Dr. Nachman catches in the film have a mutation in a gene
that leads to the dark fur color.
Why do dark-colored rock pocket mice on dark lava flows have white bellies? - answer
There is no selection for dark bellies by visual predators.
*The color of a rock pocket mouse's belly is not visible to a predator and therefore is not
under strong selection pressure.
Mutations are always __________. - answera change in an individual's DNA
*Mutations are rare genetic changes that can be neutral, beneficial, or detrimental
depending on an individual's circumstances. A dark-color fur mutation is good for a rock
pocket mouse living on black lava and bad for one living in the sandy desert.
When dark-colored fur gives mice a 1% competitive advantage and 1% of the
population begins with dark fur, in about 1000 years, 95% of the population will have
dark fur. Which of the following statements is true? - answerIf dark-colored rock pocket
mice had a competitive advantage of 0.1%, it would take longer for 95% of the
population to have dark fur.
*A small evolutionary advantage can lead to large changes in a population. The larger
the advantage, the faster the changes occur.
What does Dr. Carroll mean when he says, "while mutation is random, natural selection
is not"? - answer- Mutations for advantageous traits are more likely to be passed on to
the next generation.
- Natural selection favors some mutations.
- Natural selection acts on traits.
, *Natural selection can only work on variation existing in a population. Mutation creates
variation randomly. Natural selection is not random; by determining which traits are
passed to the next generation, it can shape populations.
In the lab, Nachman examined dark mice from two different populations living hundreds
of miles apart. The mice looked nearly identical. Their dark color was caused by two
different genes. What does this tell you? - answer- Under very similar conditions, natural
selection can favor very similar adaptations.
- There are at least two genes involved in creating dark mouse fur.
- Two completely different mutations in two separate genes can generate the same
phenotype.
- Dark fur color evolved independently on each lava flow.
From his observations of organisms in the Galapagos islands, Darwin reasoned that
_____. - answerorganisms had adapted to new environments, giving rise to new
species
*Darwin reasoned that natural selection had increased the match between the
organisms and their environment.
This experiment is an example of hypothesis-based science.
What question did the researchers ask? - answerCan predation result in selection for
color patterns in guppies?
*Researchers transplanted guppies from pools containing pike-cichlid fish (intense
guppy predators) to pools containing killifish (less active predators that prey mainly on
juvenile guppies). They then determined whether color patterns in the transplanted
population changed over time.
What was the researchers' main hypothesis? - answerPredation results in selection for
more drab color patterns in guppies.
*Researchers hypothesized that predation should result in selection for more drab
colors in guppies because guppies with bright colors are more conspicuous to
predators.
Researchers further hypothesized that if predation pressure is reduced, drab coloration
would become less beneficial (since females prefer brightly colored mates). Based on
this hypothesis, what prediction did the researchers test in this experiment? -
answerWhen guppies with drab colors are transferred to a pool with only killifish, the
transplanted population will evolve brighter colors than the original source population.
*In pools with only killifish, predation would not counteract selection pressure resulting
from female guppies' preference for brightly colored males. As a result, the guppies
should evolve to be more brightly colored than the source population.
