1
What is biodiversity, and why is it important? How many species are estimated to live on Earth, and which taxonomic groups have the most species?
INFOGRAPHICS 12.1 AND 12.2
Give a basic definition of biodiversity.
The variety of life on Earth, including the many different species that are present as well as the differences between individuals within a single species.
The total number of different species on Earth:
is unknown, but insects are the most numerous species.
is a few million, mostly bacteria and fungi.
is more than 20 million, with half of them being plants.
is less than 1 million, mostly vertebrates.
A
Why is biodiversity loss a concern?
It primarily occurs in the developed world, where most of the world’s population lives.
It increases the degree of endemism in an area.
It primarily affects well-known and charismatic species like elephants and orangutans.
It disrupts ecological connections, potentially diminishing ecosystem services.
D
2
How do genetic, species, and ecosystem diversity each contribute to ecosystem function and services?
INFOGRAPHIC 12.3
True or False: As ecosystem diversity increases, so does species diversity.
TRUE
All apples belong to the species Malus domestica. The wide variety of apples available in the produce department of your local grocery store is an example of __________ diversity.
Genetic
An example of species diversity might be:
the wide variety of coloration and tail size in guppies.
the diverse habitat types and organisms inhabiting a deep lake, its edges, and the surrounding meadow and forest areas.
the many different species inhabiting a swamp.
None of the above.
C
Define genetic diversity and use the example of the potato blight in Ireland to explain the importance of genetic diversity to a population.
Genetic diversity, the inherited differences among individuals in a population, increases the chances that some individuals of the population will be able to survive environmental changes and perpetuate the species. Because all the potatoes in Ireland were identical in their inability to resist the blight, they all died. If the population had possessed genetic diversity, perhaps some potatoes would have survived. Even if the crop yield was low, these survivors could have been planted and produced a crop in the next year.
3
What are biodiversity hotspots, and why are they important?
INFOGRAPHIC 12.4
True or False: Biodiversity hotspots are areas with many endemic species that are well protected and not threatened with endangerment.
FALSE
A species that naturally occurs in only one place is called:
an endangered species.
a hotspot species.
an endemic species.
a threatened species.
C
4
What role does isolation play in a species’ vulnerability to extinction? How do habitat destruction and fragmentation threaten species?
INFOGRAPHICS 12.5, 12.6, AND 12.7
The leading human cause of species endangerment is __________ __________.
Habitat destruction
Why are many of the biodiversity hotspots around the world on islands?
Islands accumulate species from many different areas.
Populations of island species are isolated.
Islands have more diverse habitats.
There are more niches on islands.
B
Why are isolated populations more vulnerable to extinction than populations that are not isolated from each other?
Isolated populations usually have less genetic diversity than populations which are not isolated and can freely exchange genetic material (through dispersal of breeding individuals). This lower genetic diversity reduces the adaptability of the population — if environmental conditions change, there might not be any (or enough) population members able to survive the change.
5
How can we acquire the food, fiber, fuel, and pharmaceutical resources we need without damaging the ecosystems that provide those resources?
TABLE 12.1
True or False: Sustainable solutions to growing oil palms must consider the needs of consumers and nearby communities.
TRUE
In terms of its impact on species and their environment, producing palm oil may be a better option than producing soybean oil because:
palm oil is less expensive to grow.
oil palm trees are not grown in areas with very many endangered species.
palm oil is easier to extract from the seed than soybean oil.
growers can produce more oil per hectare with palm plantations than soybean fields.
D
Evaluate the trade-offs of using palm oil as a replacement for trans fats and make a recommendation regarding our future path that considers economic, environmental, and societal needs.
Answers will vary but the recommendation should be supported by the trade-off analysis.
How can you, as an individual, help maintain biodiversity worldwide? Justify your choices.
Answers will vary but should include a justification for the usefulness of the action.
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