Mastering Biology Chapter 22
What was the researchers' main hypothesis?
Predation results in selection for more drab color patterns in guppies.
Charles Darwin _____.
proposed natural selection as the mechanism of evolution
What was the control group in this study?
the source population in the pike-cichlid pools
Identify the four postulates of natural selection.
-Individuals with certain traits are more likely to survive and reproduce. -Individuals in a population vary in the traits they possess. -Some trait differences are heritable. -Survival and reproductive success are variable among individuals in a population.
What does Dr. Carroll mean when he says, "while mutation is random, natural selection is not"?
-Mutations for advantageous traits are more likely to be passed on to the next generation. -Natural selection acts on traits. -Natural selection favors some mutations.
Some monkey flowers (Mimulus guttatus) living near the sites of copper mines can grow in soil containing high concentrations of copper, which is toxic to most plants. Copper tolerance is a heritable trait. The map below shows the area near an old copper mine, which contaminated the nearby soil with copper. A stream flows past the mine toward the lake at the bottom right of the map.
-Nearly 100% of monkey flowers growing in copper-contaminated soil are copper tolerant. -If you were to test monkey flowers growing on the shore of the lake, you would expect nearly 100% of them to be copper tolerant. -The population that existed before mining must have included both copper-tolerant and copper-intolerant plants.
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?
-Two completely different mutations in two separate genes can generate the same phenotype. -Dark fur color evolved independently on each lava flow. -Under very similar conditions, natural selection can favor very similar adaptations. -There are at least two genes involved in creating dark mouse fur.
This experiment is an example of hypothesis-based science. What question did the researchers ask?
Can predation result in selection for color patterns in guppies?
Which of the following statements is an accurate combination of postulates 1 and 2 of natural selection?
Heritable variation exists for traits among individuals in a population.
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?
If 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.
Which of the following statements is an accurate combination of postulates 3 and 4 of natural selection?
Individuals experience differential success in their ability to survive or reproduce due to differences in certain traits.
Does the ability of a Mycobacterium tuberculosis cell to infect a new host depend on its drug-resistant phenotype?
No, drug-susceptible cells and drug-resistant cells are equally likely to infect a new host.
What conclusion would you draw from the data presented?
Predation results in selection for more drab coloration in pike-cichlid pools.
In the United States today, about half of the corn crop is genetically engineered with a protein that is toxic to corn borers, an insect pest of corn. Which of the following conditions would be necessary for evolution of resistance to the toxic protein to occur in the corn borer?
The corn borer must have or generate (by mutation) heritable variation in resistance to the toxic protein. The resistant corn borers must survive better or reproduce more than nonresistant corn borers.
Which of the following statements describes the evolution by natural selection of Mycobacterium tuberculosis bacteria in their new environment?
The drug-resistance trait is an adaptation to the environment in which human hosts are medicated with the antibiotic rifampin.
Why do dark-colored rock pocket mice on dark lava flows have white bellies?
There is no selection for dark bellies by visual predators.
Why did dark-colored rock pocket mice first appear in a population of light-colored rock pocket mice?They have a genetic mutation that affects their fur color.
They have a genetic mutation that affects their fur color.
Suppose that after 22 months, guppies from the transplanted population were returned to the source pool. What would most likely happen to those guppies?
They would experience a higher rate of predation than the native population, and over time they would evolve and resemble the original source population.
How did the types of data the researchers collected enable them to test their prediction?
Tracking the number and area of colored spots provided a quantitative way to compare the brightness of different populations.
True or false? It would be difficult to assess whether the drug-susceptible or drug-resistant phenotype in a population of Mycobacterium tuberculosis was more fit in an environment without antibiotics.
True
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?
When guppies with drab colors are transferred to a pool with only killifish, the transplanted population will evolve brighter colors than the original source population.
Mutations are always __________
a change in an individual's DNA
A challenge to traditional (pre-1860) ideas about species came from embryology, when it was discovered that _____.
embryos of dissimilar organisms, such as sharks and humans, resemble each other
The wing of a bat is homologous to the _____ of a whale.
flipper
Which of the following would help strengthen the researchers' conclusion?
if no other characteristics differed significantly between the source and transplanted populations
From his observations of organisms in the Galapagos islands, Darwin reasoned that _____.
organisms had adapted to new environments, giving rise to new species
What data should you collect in order to test your prediction?
predation rate on transplanted versus original source guppies, and color patterns of the population over time
What was the experimental group in this study?
the transplanted population in the killifish pools