In a species of snail, dark-shelled individuals are better hidden from bird predators in the shady forest, while light-shelled individuals are better hidden in well-lit brushy edge areas. If there were no areas of intermediate brightness in this habitat, which type of selection would act on shell color in these snails?
Small lizards have difficulty defending their territory, but large lizards are more likely to be preyed upon by owls. Which type of selection would act on body size in these lizards under these conditions?
An elk herd is observed over many generations. Most of the full-grown bull elk have antlers of nearly the same size, although a few have antlers that are significantly larger or smaller than this average size. The average antler size remains constant over the generations. Which of the following effects probably accounts for this situation?
After a copper smelter begins operation, local downwind populations of plants begin to adapt to the resulting air pollution. Scientists document, for example, that the acid tolerance of several plant species has increased significantly in the polluted area. This is an example of
A rabbit population consists of animals that are either very dark on top or very light on top. The color pattern is not related to sex. No rabbit shows intermediate coloration (medium darkness). This pattern might result from
Large antlers in male elk, which are used for battles between males, are a good example of a trait favored by
Mate-attracting features such as the bright plumage of a male peacock result from
If you had to choose, where would you rather get infected with a serious bacterial disease?
In a remote, sparsely populated area where the bacteria have not been exposed to antibiotic drugs
Which of the following would most quickly be eliminated by natural selection?
a harmful allele in an asexual, haploid population
The sickle-cell allele produces a serious blood disease in homozygotes. Why doesn't natural selection eliminate this allele from all human populations?
In populations where endemic malaria is present, heterozygotes have an important advantage: They are resistant to malaria and therefore are more likely to survive and produce offspring that carry the allele.
Frequency-dependent selection, as seen in the case of the scale-eating fish in Lake Tanganyika, tends to
maintain two phenotypes in a dynamic equilibrium in a population.
Tay-Sachs is inherited as an autosomal recessive allele. Homozygous individuals die within the first few years of life. However, there is some evidence that heterozygous individuals are more resistant to tuberculosis. Which of the following statements about Tay-Sachs is true?
This situation is an example of heterozygote advantage if tuberculosis is present in a population
Mothers and teachers have often said they need another pair of eyes on the backs of their heads. And another pair of hands would come in handy in many situations. You can imagine that these traits would have been advantageous to our early hunter-gatherer ancestors as well. According to sound evolutionary reasoning, what is the most likely explanation for why humans do not have these traits?
Because these variations have probably never appeared in a healthy human. As tetrapods we are pretty much stuck with a four-limbed, two-eyed body plan; natural selection can only edit existing variations.
Scientists studying evolution on the Solomon Islands described which animal as the 'poster child' for the biological species concept?
When Darwin wrote On the Origin of Species, he knew very little about the subject of _____, an essential component of evolutionary theory today.
What does it mean to say that pigweed is resistant to herbicide?
Pigweed plants thrive despite the application of herbicides intended to kill them
In the past, herbicides were very effective as a pigweed killer, but today _____.
pigweed is taking over fields of cotton and soybeans
The scientists who produced the herbicide warned against overuse, saying that over time, ____.
resistant weeds would increase in number
Which of the following sets of animals are likely to be found on the Galapagos Islands?
tortoises, finches, blue-footed boobies
Tourism on the Galapagos Islands is being restricted by requiring tourists to _____.
be escorted by trained guides at all times
You wish to research how genetics determine color of deer mice. How many genes should you focus on?