Exam 58: A Changing Biosphere

A species of bird is critically endangered, and its habitat is rapidly disappearing.A conservationist committed to preventing the extinction of this species would be most likely to undertake which type of program in the short term?

Each country that participates in CITES issues a permit for the sale of all legal wildlife or plant species.Species listed by CITES are not permitted.At trade sites, merchandise is counted and checked to ensure its legality.In this way, the CITES agreement helps limit illegal trade in endangered species.What recent factor in elephant conservation has made enforcement of the CITES agreement less useful?

When it was established, the U.S.Forest Service instituted a "no fire" policy; they attempted to prevent forest fires and to quickly and completely suppress fires if they started.Their stated purpose was to protect the nation's timber supply.In the 1970s, they reversed this policy and now let some fires burn, especially those that start naturally.In some cases, they even start fires, a process called "controlled burning." What factor caused the Forest Service's reversal of policy on fires?

Extinctions, such as the extinction of the heath hen on Martha's Vineyard, Massachusetts, occur at the population or species level.But factors at other levels can be instrumental in causing an extinction.Which factor in the heath hens' extinction operated at the community level of diversity rather than the population level?

Plume hunting in the late 1800s to supply feather decorations for hats and clothing was responsible for the depletion and even extinction of many types of birds in the United States.This activity was an example of loss of biodiversity due to

Many native pollinators in Hawaii were driven extinct by non-native species.Now, many beautiful native Hawaiian flowers are pollinated by the Japanese white-eye bird.At first, Japanese white-eyes coexisted with native birds, but recently their numbers have increased in old-growth forests, leaving native birds too little to eat and threatening their survival.Today, the Japanese white-eye could best be classified as

Refer to the figure. The figure illustrates three ecological principles considered in the establishment of protected areas.Briefly explain why the characteristics in the "better" column (larger reserves, buffer zones, and habitat corridors) are considered superior to their opposites in terms of supporting viable populations and ecosystem services.

In the eastern United States, 28 species of migratory birds are nesting earlier in the spring than they did several decades ago, and northeastern birds that winter in the southern United States are returning north 13 days earlier than they did a century ago.These changes are most likely due to

Wild orca populations face many threats from humans.Sea World bred captive orcas from the 1980s until 2016.In captivity, orcas had their first calves much younger (8 years old) than wild orcas (14.9 years old).Captives were highly inbred and had a high number of stillbirths.Calves were later bred by artificial insemination.Suppose, in the future, orcas become endangered and the species must be saved through captive breeding and release.Based on this information, what factor or factors might limit the success of such a program?

Which situation would be considered an example of habitat degradation, as opposed to habitat loss or destruction?

A conservation group is debating the benefits of working specifically on the protection of an endangered species versus establishing a protected area that encompasses the habitat of that species.Which benefit would be provided only by the protected area option?

Introduced from Asia more than 5,000 years ago, dingoes (wild dogs) are now considered an "honorary native species" in Australia.They are the largest predators in the country.Like wolves, they hunt in packs and can bring down prey the size of buffaloes.Where dingoes are scarce, foxes and cats have caused the extinction of 20 mammals and threaten many more.Where more dingoes are present, fox and cat numbers are low, and mammal populations are protected.But farmers want to eradicate dingoes, which sometimes prey on sheep.Which would likely happen to the ecosystem if dingoes were removed?

Edge effects are often damaging to the biodiversity of the original habitat because they

Genetic drift, leading to inbreeding depression, combined with demographic stochasticity can threaten biodiversity because it results in a smaller _______.

One way ecologists try to estimate the effect of habitat loss on the rate of extinctions is by applying a concept from island biogeography known as the _______ relationship.

Refer to the figure. From the map, determine the locations in the world where overfishing is the most serious problem.Which continents or regions show high, moderate, and low exploitation? Why are the exploited areas close to continents?

Michigan scientists are trying to save the endangered Kirtland's warbler, a small songbird that breeds only in even-aged stands of jack pine.They have replanted stands of jack pine and used prescribed burning to develop stands of the middle-aged trees the warblers prefer.Which ecological concept is being used to aid this restoration ecology project?

In the past 20 to 50 years, many plants have reacted to rising temperatures by blooming earlier in the spring.Early flowering is particularly associated with insect-pollinated plants.Which would be the most likely result if insect pollinators did not also emerge earlier, or if their emergence did not coincide with flowering?

Deaths of individuals in a population could lead to genetic drift, inbreeding, and demographic stochasticity.This in turn reduces genetic diversity and fitness, which results in a smaller effective population size.This leads to a spiraling population decline known as a(n) _______.

Developers are building ten new homes on a parcel of land of one habitat type.Local zoning regulations require that they leave some of the land in its natural condition to conserve native species.They can set aside either one large plot or five small separated plots.The total amount of conserved area is the same in either case.Which choice, if either, would be best for maintaining biodiversity, and why?