Keystone predators can maintain species diversity in a community if they
prey on the community's dominant species.
allow immigration of other predators.
reduce the number of disruptions in the community.
prey only on the least abundant species in the community.
competitively exclude other predators.
Scientific study of the population cycles of the snowshoe hare and its predator, the lynx, has revealed that
the hare population is r-selected and the lynx population is K-selected.
the prey population is controlled by predators alone.
both hare and lynx populations are regulated mainly by abiotic factors.
hares and lynx are so mutually dependent that each species cannot survive without the other.
multiple biotic and abiotic factors contribute to the cycling of the hare and lynx populations.
Although many chimpanzees live in environments containing oil palm nuts, members of only a few populations use stones to crack open the nuts. The likely explanation is that
members of different populations have different nutritional requirements.
the cultural tradition of using stones to crack nuts has arisen in only some populations.
members of different populations differ in manual dexterity.
the behavioral difference is caused by genetic differences between populations.
members of different populations differ in learning ability.
Which of the following statements about human population in industrialized countries is incorrect?
The survivorship curve is Type I.
Average family size is relatively small.
Age distribution is relatively uniform.
The population has undergone the demographic transition.
Life history is r-selected.
Graylag goslings imprint on a nearby object that moves away from them during a sensitive period in the first few hours after they hatch, and follow the object steadfastly from that time on. What is the adaptive value of this behavior?
This behavior is not adaptive because goslings may imprint on objects other than their parents.
This behavior is likely to increase gosling survival.
This behavior is genetic.
aprey on the community's dominant species.
bmultiple biotic and abiotic factors contribute to the cycling of the hare and lynx populations
cthe cultural tradition of using stones to crack nuts has arisen in only some populations.
dLife history is r-selected.
eThis behavior is likely to increase gosling survival.
5 Multiple Choice Questions
Behaviors with a genetic component can evolve through natural selection.
Changes in the behavior of cross-fostered young provide information about how the social and physical environment influences behavior.
Cross-fostering studies provide information about the relative importance of nature and nurture in the development of a trait.
Disturbances can create patches of different habitats in a community.
Dispersal occurs only on an evolutionary time scale.
determine the birth rate and death rate of each group in a population.
5 True/False Questions
Consider a population whose growth over a given time period can be described by the exponential model: dN/dt = rN. Select the correct statement about this population.
A population with an r of 0 will have no births or deaths during the time period under consideration.
A population with a positive value of r will grow exponentially.
A population with an r of 0.1 will decrease over time. → the rate of decomposition in the ecosystem
The observation that members of a population are uniformly distributed suggests that
the members of the population are competing for access to a resource.
the size of the area occupied by the population is increasing.
resources are distributed unevenly.
the members of the population are neither attracted to nor repelled by one another.
the density of the population is low. → the members of the population are competing for access to a resource.
When climbing a mountain, we can observe transitions in biological communities that are analogous to the changes
in a community through different seasons.
in biomes at different latitudes.
in an ecosystem as it evolves over time.
at different depths in the ocean.
across the United States from east to west. → in biomes at different latitudes.
According to Hamilton's rule,
natural selection is more likely to favor altruistic behavior that benefits an offspring than altruistic behavior that benefits a sibling.
natural selection favors altruistic acts when the resulting benefit to the beneficiary, corrected for relatedness, exceeds the cost to the altruist.
natural selection does not favor altruistic behavior that causes the death of the altruist.
altruism is always reciprocal.
the effects of kin selection are larger than the effects of direct natural selection on individuals. → Dispersal occurs only on an evolutionary time scale.
Gray wolves, once the top predators in Yellowstone National Park, were hunted to extinction there in 1926. In 1995, 15 wolves were brought to Yellowstone from Alberta. The wolf population has now grown to 300.
The forest community in Yellowstone National Park can be described by a top-down model of community organization. Wolves hunt and eat elk. Elk are herbivores that prefer riparian vegetation (plants growing next to streams and lakes). Ravens, bears, and eagles feed on elk carcasses.
How would you expect the return of the wolves to Yellowstone to affect the other species there?
Select all that apply.
Riparian vegetation would decline.
Elk populations would decline.
Bear populations would decline. → Elk populations would decline.