Deck 59: Conservation Biology

Question 1

To effectively address the biodiversity crisis, the protection of individual species

A) must be used in concert with a principle of ecosystem management and restoration.
B) is a sufficient management approach that merely needs to be expanded to more species.
C) has no role to play in addressing the biodiversity crisis.
D) usually conflicts with the principle of ecosystem management.

Answer 1

(A) Efforts are being undertaken worldwide to preserve biodiversity in networks of reserves and other less protected areas designed to counter the influences of habitat fragmentation. Focusing on the health of entire ecosystems, rather than particular species, can often be a more effective means of preserving biodiversity.

Question 2

If 99% of the species that ever existed are now extinct, why is there such concern over the extinction rates over the last several centuries

Answer 2

Extinction is a fact of life. More than 99% of species once known are now extinct. Current rates of extinction are alarmingly high. Taking into account the current rapid and accelerating loss of habitat, especially in the tropics, it has been found that 20% of the world's biodiversity may be lost by the middle of this century. Historical extinction rates are best known for birds and mammals since they are conspicuously present. The majority of extinctions have occurred in last 150 years. This increase in the rate of extinction is the heart of the biodiversity crisis. Efforts are being undertaken worldwide to preserve biodiversity in networks of reserves and other less protected areas designed to counter the influences of habitat fragmentation. Focusing on the health of entire ecosystems, rather than particular species, can often be a more effective means of preserving biodiversity.
Species often vulnerable to extinction when their web of ecological interactions becomes seriously disrupted. Because of the many relationships linking species in an ecosystem, human activities that affect one species can have ramifications throughout an ecosystem, ultimately affecting many other species.
Keystone species plays a particularly important role in its community and are usually characterized by the strength of their impact on their community. Loss of keystone species may disrupt ecosystems.

Question 3

Historically, island species have tended to become extinct faster than species living on a mainland. Which of the following reasons can be used to explain this phenomenon

A) Island species have often evolved in the absence of predators and have no natural avoidance strategies.
B) Humans have introduced diseases and competitors to islands, which negatively affects island populations.
C) Island populations are usually smaller than mainland populations.
D) All of the above.

Answer 3

(D) The major historic extinctions have occurred on islands because such species have often evolved in the absence of predators, and so have lost their ability to escape both humans and introduced predators like rats and cats. In addition, humans have introduced competitors and diseases like malaria that has devastated the bird fauna of the Hawaiian Islands. Finally, island populations are often relatively small, and thus are vulnerable to extinction

Question 4

Ecosystem conversion always has a cost and a benefit. Usually the benefit flows to a segment of society (a business or one group of people, for instance), but the costs are borne by all of society. That is what makes decisions about how and when to convert ecosystems difficult. However, is that a problem unique to conversion of ecosystems in the way we understand it today (for example, the conversion of the mangrove to a shrimp farm) Are there other examples we can look to for guidance in how to make these decisions

Question 5

Conservation hotspots are best described as

A) areas with large numbers of endemic species, in many of which species are disappearing rapidly.
B) areas where people are particularly active supporters of biological diversity.
C) islands that are experiencing high rates of extinction.
D) areas where native species are being replaced with introduced species.

Question 6

There is concern and evidence that amphibian populations are declining worldwide as a consequence of factors acting globally. Given that we know that species extinction is a natural process, how do we determine if there is a global decline that is different from normal species extinction

Question 7

Biodiversity hotspots

A) cover 1.4% of the world's land surface but are home to 35% of extant terrestrial vertebrate species.
B) cover 35% of the world's land surface but are home to 1.4% of extant terrestrial vertebrate species.
C) are found only on islands.
D) are found only in the tropics.

Question 8

The ability of an intact ecosystem, such as a wetland, to buffer against flooding and filter pollutants from water is a(n) _____ value of biodiversity.

A) direct economic
B) indirect economic
C) ethical
D) aesthetic

Question 9

The economic value of indirect ecosystem services

A) is unlikely to exceed the economic value derived from uses after ecosystem conversion.
B) has never been carefully determined.
C) can greatly exceed the value derived after ecosystem conversion.
D) is entirely aesthetic.

Question 10

The amphibian decline is best described as

A) global disappearance of amphibian populations due to the pervasiveness of local habitat destruction.
B) global shrinkage of amphibian populations due to global climate change.
C) the unexplained disappearance of golden toads in Costa Rica.
D) None of the above

Question 11

Habitat fragmentation can negatively affect populations by

A) restricting gene flow among areas that were previously continuous.
B) increasing the relative amount of edge in suitable habitat patches.
C) creating patches that are too small to support a breeding population.
D) all of the above.

Question 12

A keystone species is one that

A) has a higher likelihood of extinction than a nonkeystone species.
B) exerts a strong influence on an ecosystem out of proportion to its abundance.
C) causes other species to become extinct.
D) has a weak influence on an ecosystem.

Question 13

When populations are drastically reduced in size, genetic diversity and heterozygosity

A) are likely to increase, enhancing the probability of extinction.
B) are likely to decrease, enhancing the probability of extinction.
C) are usually not factors that influence the probability of extinction.
D) automatically respond in a way that protects populations from future changes.

Question 14

A captive-breeding program followed by release to the wild

A) is very likely, all by itself, to save a species threatened by extinction.
B) is only likely to succeed when genetic variation of wild populations is very low.
C) may be successful when combined with proper regulations and habitat restoration.
D) None of the above

Question 15

Ninety-nine percent of all the species that ever existed have gone extinct,

A) serving as evidence that current extinction rates are not higher than normal.
B) but most of these losses have occurred in the last 400 years.
C) which argues that the world just had too many species.
D) None of the above