Exam 58: A Changing Biosphere

Ocean fisheries have been a major source of human food for centuries.But with the rapid rise of human populations and the development of high-tech fishing gear, extreme overharvesting of many species has occurred in the last century.This harvesting for food contrasts with harvesting by people who obtain and sell aquarium fish from coral reefs.Compare and contrast these two types of overharvesting.How does overharvesting affect the ecosystem in each case?

A fern lives in the tropical rainforest and depends on the dense shade of the forest to survive.Then the rainforest where the fern lives is cut down and replaced with open pastureland, which is warmer and drier.The fern goes extinct.This is an example of biodiversity loss due to

In Southern California, scientists watched 15 culverts and underpasses and found that various carnivores, mule deer, small mammals, and reptiles traveled through them to other parts of the area.Although not designed for that purpose, the culverts and underpasses served as

Arctic ice algae grow in nutrient-rich pockets in and under sea ice.The algae are food for zooplankton, which are eaten by Arctic cod.The cod are eaten by marine mammals such as seals, which in turn are eaten by polar bears.As Arctic temperatures warm and sea ice melts, there is less and less habitat for ice algae.How will this change affect this Arctic food web?

The recent rediscovery of the pygmy tarsier, thought to be extinct for the previous 85 years, suggests that

Major causes of the global decrease in biodiversity include all of the following except

Refer to the figure. Study the maps showing changes in vegetation in the eastern United States since the last ice age, 18,000 years ago (18 ka).Describe the change in patterns for mixed forest, deciduous forest, and southeast forest.What general conclusions can you draw about the movement of vegetation as ice melted and receded to the north? How does this pattern relate to changes occurring today?

For more than 200 years, sea otters were exploited for their beautiful pelts.When otter populations declined, populations of their main food source, sea urchins, exploded.Urchins then overharvested kelp, their primary food source, leaving areas barren of kelp and depriving many other species of habitat.This description suggests that the species in this ocean ecosystem that were harmed by sea otter overharvesting included

The cane toad is native to Central and South America and can grow to be a foot long.It was introduced into Hawaii, the Philippines, and the Caribbean to control pests in sugarcane fields.It quickly became a serious pest itself because it eats anything it can fit into its mouth.It also secretes a powerful toxin.The cane toad can best be described as a(n) _______.

Overharvesting would most likely result in extinction for a species that is

Winter moth, a species of moth that was introduced to the United States from Europe, has spread widely and become a threat to many trees.Winter moth would be classified as a(n) _______ species.

Controlling the spread of invasive species around the world is especially difficult because of the

The extinction of heath hens, a subspecies of prairie chickens (in the grouse family), on Martha's Vineyard, Massachusetts, was the result of

What major factor prevents the use of captive breeding programs as a solution for saving endangered species?

A national park in Bolivia was designed with three distinct areas.Area A is a large central area designated "no extraction"; no resources of any kind can be removed from it.Area B is a large surrounding area populated by indigenous peoples and designated to allow them to continue to farm and hunt there.Outside both areas, area C is zoned for "extractive" uses (for example, livestock raising and a gas pipeline).What terms would best describe areas A and B, respectively?

The fungal pathogen Batrachochytrium dendrobatidis, or Bd, has been strongly implicated in the decline of amphibians around the world.Researchers are currently debating whether Bd is a novel pathogen, recently introduced into wild populations (the "novel pathogen hypothesis"), or whether it existed before the declines and emerged because of human-caused environmental changes (the "emerging endemic hypothesis").Based on what you know about this disease and its spread, which hypothesis seems more likely? Justify your choice.

Refer to the graph. So far, the IUCN has assessed more than 76,000 species, but there are at least 8.7 million species on Earth (probably more), and most of them are invertebrates.Few plants and invertebrates have been assessed.Their list of at-risk organisms is heavily skewed toward vertebrates, which are larger and easier to measure.Given this knowledge, what is the most reasonable conclusion that can be drawn regarding the at-risk groups shown on the graph?

To accommodate the needs of various local groups, park managers in the Philippines maintained the outer boundaries of a national park but adjusted the internal boundaries.They defined a core area where biodiversity was completely protected, and they assigned several outer multiple-use zones.These multiple-use zones might also be called _______.

The government must assess a species' extinction risk and decide that it is endangered before it can be placed on the U.S.endangered species list.This usually happens in response to a petition from an environmental group or other agency.Which factor is most likely to cause the government to reject the species (that is, decide not to place it on the endangered list)?

Leatherback turtles occur in the Atlantic, Pacific, and Indian oceans and migrate among all three oceans.In 1980, there were 115,000 nesting females globally; by 2015, that number had dropped to between 26,000 and 43,000.This decline resulted from poaching for eggs and meat, destruction of nesting sites, accidental catches by fishermen, disorientation of nestlings due to artificial lighting from coastal developments, and more.What does this information suggest about the future of leatherback turtles?