Exam 58: A Changing Biosphere

A species of mussel is accidentally introduced into ballast water in Europe.The best way to prevent its becoming established at its destination in the United States is to

Two populations of an endangered species exist in separate locations.Population A has 20 individuals.Population B has 200 individuals.Each population undergoes accidental deaths during the year that reduce their respective numbers by 10 percent.Which population, if either, has a greater chance of extinction, and why?

Which of these populations is least likely to be at risk of extinction?

Which organisms would likely be the slowest to shift their range as a result of climate change?

The rapid growth of human populations is often cited as a causal factor in declining biodiversity.Human population growth would likely be implicated in all of these causes of declining biodiversity except

Vegetation protects the soil from erosion, and insect pollinators are necessary for the successful production of many food crops.These two functions depend on biodiversity and illustrate which reason for its importance?

The pangolin, or scaly anteater, a native of Asia and Africa, is the most trafficked animal in the world.In a single decade, more than a million pangolins were poached and sold for their meat and scales.Which method would conservationists likely use to most rapidly stem the loss of pangolins?

Since 1980, the world population of leatherback turtles has dropped by 63-77 percent.This decline has 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.This suggests that the decline in the leatherback turtle population is almost entirely due to _______, not natural, causes.

Biological control is the deliberate introduction of one species into an area to control an already invasive species.Mongooses were introduced to several Hawaiian islands in the 1880s to control rats in sugar cane fields.However, rats are nocturnal and mongooses are diurnal, so the two species never crossed paths.Instead, mongooses feed on nestlings and eggs of rare ground-nesting birds and endangered sea turtles.Mongooses usually avoid traps if prey is abundant.The U.S.Army is now trying a new mongoose trap used successfully in New Zealand.Based on this information, what can be said about the use of mongooses as a biological control method in this case?

A species can be considered invasive if it

Scientists varied the effective population size of a wildflower in a natural setting.After several generations, they found that populations with lower effective population sizes had lower rates of germination and survival because of inbreeding depression.This suggests that a low effective population size might eventually lead to

The Convention on Biological Diversity finds that about 40 percent of the world's economy and 80 percent of the needs of the poor depend on biological resources, that is, biodiversity.This suggests that

Of these locations, the one most likely to be described as a human-natural system is a(n)

A decline in U.S.puma populations over the past 60 years has caused drastic increases in deer populations and significant decreases in populations of hardwood trees, non-avian reptiles, and butterflies.This suggests that declines in puma, a top predator, led to a disruption in the food web that caused the ecological process known as a(n) _______.

Members of a conservation organization have funding to establish two protected areas.They can purchase either two 200 km² parcels of land or one parcel that is 400 km².Which option (if either) would best meet the goals of a protected area-protecting species and retaining the functions and services of the original ecosystem?

Ninety-eight percent of saltwater aquarium fish cannot be bred in captivity and are taken directly from coral reefs around the world.More than 90 percent of the 11 million fish entering the United States each year are captured by applying cyanide onto the reef.This kills many fish; others are stunned, scooped up, and sold.Many of them die in transit or soon after being sold.Also, for every live fish caught, about a square yard of coral is destroyed.Which action would likely be the most effective way to save the reef fish and the coral reef itself?

An invasive snail is accidentally introduced into a river.It carries a pathogen to which it is adapted; however, the pathogen is a generalist that can infect various other mollusk species in the river and downstream.What is the most likely effect the introduced pathogen will have on the mollusk diversity of the river?

When the brown tree snake was introduced onto the island of Guam, its introduction resulted in the

Habitat corridors, such as the overpasses across the Trans-Canada Highway, are most helpful in protecting biodiversity when they are used to connect

Unsustainable fishing, or overharvesting, of many ocean fish species is now occurring.What, if any, is a major ecological impact of this overharvesting?