Chapter 11. Chapter 11: Preserving Biodiversity

What are the major causes of species endangerment and extinction today?

Why You Should Care

When you were younger and learned about the dinosaurs and how they all went extinct long ago, it probably seemed like they all died out on the same day. Although past mass extinctions, like the one that killed the dinosaurs, did happen rapidly in geological time, they still took millennia to occur. Would it surprise you to know that we are currently in the most catastrophic mass extinction known to science?

Not only are we in the midst of another mass extinction event, but rather than a meteor collision or an ice age, the main cause of this mass extinction is human activity. In developing land for agriculture, industry, business, and dwellings, humans destroy and fragment habitat suitable for other species. One of the most notorious examples of this is suburban and exurban strip development. Rather than create a compact, pedestrian-friendly, neighborhood-building commercial center around existing small towns, it is more convenient and cost-effective (in the short term) to build commercial developments along high corridors. This means that land that was less developed and probably supported a more natural community of species was plowed under rather than re-developing existing neighborhoods and minimizing the land area disturbed by humans. Humans also over-pollute the environment through industry as well as waste. A by-product of our pollution is global climate change through increasing greenhouse gas emissions. The effect of climate change is most dramatic at the poles, where already fragile ecosystems are rapidly disappearing. A negative side of human globalization is that we tend to move other species with us, and, often, these species become invasive and damage ecosystems. The introduction of cats, rats, goats, and pigs by sailors travelling around the world has caused the extinction of more than one species. Humans are also over-harvesting and overusing natural resources. Whales were over-hunted in the eighteenth and nineteenth centuries, and despite international treaties protecting them, many species have yet to recover their former numbers.

Every species that is lost from the biosphere diminishes the variety of species with which we share the planet. We are heading toward a world of uniformity, in which there are only a handful of species of plants and animals in all the biomes. We have to decide if that’s a world we can live with because there is still time to take action to reduce extinction rates.

1.

Because of its location on the Chesapeake Bay, Maryland became famous for blue crabs, but now the state must set fishing limits every season so that crab populations don’t crash. This best describes an example of:

A.

overexploitation.

B.

invasive species.

C.

climate change.

D.

pollution.

E.

habitat destruction and fragmentation.

999

Try again.

Correct.

Incorrect.

2.

In North America, some plant species—sugar maple, for example—have begun to shift their native ranges. They are either moving northward, to higher elevations, or both. This is often accompanied by retreat of the species from more southerly latitudes and lower elevations. For some of these species, there is a chance that they might eventually run out of suitable habitat. This shift is probably due to:

A.

overexploitation.

B.

invasive species.

C.

climate change.

D.

pollution.

E.

habitat destruction and fragmentation.

999

Try again.

Correct.

Incorrect.

3.

In some arctic and subarctic areas where oil is drilled, the oil pipelines have been raised to allow caribou to continue their typical migration patterns. This describes an attempt to alleviate the problem of:

A.

overexploitation.

B.

invasive species.

C.

climate change.

D.

pollution.

E.

habitat destruction and fragmentation.

999

Try again.

Correct.

Incorrect.

4.

Acid precipitation occurs when gaseous by-products of combustion, especially from internal combustion engines, mix with the humidity in the atmosphere to become acids that then fall back to the ground. Acid precipitation can kill trees and poison fish. This describes the problem of:

A.

overexploitation.

B.

invasive species.

C.

climate change.

D.

pollution.

E.

habitat destruction and fragmentation.

999

Try again.

Correct.

Incorrect.

5.

The brown marmorated stinkbug is native to Asia but was accidentally brought to North America in the 1990s. It has spread widely and may pose a threat to the native green stinkbug. The brown marmorated stinkbug is a good example of:

A.

overexploitation.

B.

an invasive species.

C.

climate change.

D.

pollution.

E.

habitat destruction and fragmentation.

999

Try again.

Correct.

Incorrect.

6.

The three most common reasons that vertebrate species have become threatened or endangered all relate at least in part to:

A.

overexploitation.

B.

invasive species.

C.

climate change.

D.

pollution.

E.

habitat destruction and fragmentation.

999

Try again.

Correct.

Incorrect.

7.

Rank the following in terms of greatest to smallest (1 being the greatest) percentage of threatened vertebrates affected:

--------123 Climate change

--------123 Pollution

--------123 Invasive alien species

999

Try again.

Correct.

Incorrect.

8.

Thought Question: Describe habitat preferences, reproduction, ability to disperse, life span, etc. in general terms for the following:

1) A hypothetical species that is likely to become invasive if moved to a new habitat.

2) A hypothetical species that is highly likely to become threatened due to climate change.

1) A species that is likely to become invasive would probably have a broad range of habitat tolerances, would reproduce quickly, and would be good at dispersal. Life spans, or at least generation times, are more likely to be short.

2) A species highly susceptible to climate change would have a narrow range of habitat tolerances and be a relatively poor disperser; this would mean it would have both a hard time dealing with changes in climate and moving to a new area with a more suitable climate. This species would probably have a lower reproductive output, probably also coupled with longer life spans or generation times.

Activity results are being submitted...