CHAPTER 19 DESCENT WITH MODIFICATION
Scientific Skills Exercise
Teaching objective: Students build scientific skills by making and testing predictions on how
natural selection will affect color patterns in guppies.
Teaching tip: A version of this Scientific Skills Exercise can be assigned in MasteringBiology.
Answers:
1. (a) Can predation result in selection for color patterns in guppies? (b) Predation can result in
selection for less noticeable (more drab) coloring in prey populations of guppies. (This
hypothesis implies that reduced predation would result in a more brightly colored guppy
4. If the hypothesis is correct, then the transplanted guppies that are returned should experience a
higher rate of predation than the guppies already in the source pool, because their brighter colors
Suggested Answers for End-of-Chapter Essay Questions
See the general information on grading short-answer essays and a suggested rubric at the
beginning of this document.
7. Focus on Evolution
Organisms share many characteristics from their common descent, and more closely related
8. Focus on Interactions
Sample key points:
All organisms interact with the living and nonliving components of their environment.
An organism whose inherited traits cause it to be particularly successful in its environmental
interactions will tend to leave more offspring than other organisms.
change in one or more of the species affected by the change in environmental conditions.
Sample top-scoring answer: All organisms interact with the living and nonliving components
of their environment. Furthermore, as a result of descent with modification by natural selection,
an organism whose inherited traits cause it to be particularly successful in its environment will
9. Synthesize Your Knowledge
The expandable abdomen of the honeypot ants is an adaptation that allows them to store food