1. The
species richness of insects on trees can be predicted by which of the
following?
·
The evapotranspiration rate; The area
hypothesis
2. Support
for the succession mechanism of tolerance is found in research on plant
communities that shows succession is determined largely by species that exist
in the ground as seeds or old roots.
3. What
is the general global pattern of species richness? Increasing from polar areas
towards the tropics.
4. Disturbances
to most communities, whether windstorms, floods, or the introduction of a new
predator, are quite common. Community stability involves both the ability to
resist change in the face of disturbance and the ability to recover from change
induced by disturbance. The disturbance-stability hypothesis predicts that species-rich
communities will be more stable than species-poor communities because species-rich
communities are more likely to have disturbance-resistant species that will
increase in numbers in the face of a disturbance, compensating for
disturbance-sensitive species that might decline in numbers temporarily.
5. Various
hypotheses have been proposed to explain the patterns of species richness seen
across the globe. Below is a list of statements and comments that apply to one
of the three hypotheses.
·
Time hypothesis
¨ Communities
diversify with age
¨ Temperate
regions are younger than tropical regions
¨ The
period since the most recent severe disturbance is key
·
Area hypothesis
¨ Larger
parcels of habitat have more species than smaller parcels
¨ Higher
habitat diversity can support more species
·
Productivity hypothesis
¨ The
greater the rates of photosynthesis, the higher the species richness
¨ The
greater the plant biomass, the higher the species richness
¨ Higher
temperatures and more water means a higher diversity
6. An
example of what a community ecologist would study is the interactions among
several species of fish, the aquatic vegetation, and other animal species in a
coral reef habitat.
7. The
intermediate-disturbance hypothesis predicts that the most species rich
communities would contain both r- and K-selected species,
8. Complete
the sentences explaining how early colonizers can facilitate the colonization
of other species,
§ One
type of primary succession begins after a glacier retreats leaving rocks and
debris behind but not soil.
§ Initially,
mosses and lichen colonize the area and thrive despite the lack of soil. They
are not dependent on a soil substrate and can prosper on barren rocky lands. As
the initial colonizer die and decay, there is a build up of soil and an
increasing amount of nitrogen and other nutrients in the substrate.
§ As
a result of facilitation by the initial colonizer, flowering herbaceous plants
are able to establish. As these species die and decay, the soil depth will
increase and become enriched with nutrients.
§ With
an increase in the soil depth and nitrogen, there is an emergence of r-selected
speces, such as the alder trees, which is a fast growing tree species. The
alder has nitrogen-fixing bacteria within its roots, which facilitates its
growth.
§ Then
K-selected species, such as spruce trees, begin to take over and dominate the
faster growing species. The soil composition continues to be modified due to
the break down of the needles from the evergreen trees, allowing the
colonization by hemlock trees.
9. No
matter what model is used to show community succession, the final stage is
always a climax community.
10. The
productivity and area hypotheses together suggest that a large, tropical
continent would likely have high species richness.
11. Based
on the principle of species individuality, how would you predict that climate
change would affect the geographical range of species within a community? Each
species would shift its range in a unique manner, according to its
physiological needs.
12. In
the organismic model, communities are viewed as superorganisms. True
13. Following
a disturbance, a community goes through a predictable series of changes
depending on the level and severity of the disturbance. For each description,
indicate whether it is consistent with primary or secondary succession.
§ Primary
succession
·
No plants, animals, or microbes present
·
Bare ground, no soil
·
Occurs after a volcanic eruption
·
Occurs after a retreat of a glacier
§ Secondary
succession
·
Supports life immediately following the
disturbance
·
Occurs after a fire or tornado
·
Soil present
·
Severity varies, but it is never
completely lifeless
14. The
individualistic model of a community as an assemblage coexisting primarily of
species similar in their physiological requirements was proposed by Henry Allan
Gleason.
15. You
discover a subterranean river in the outback of Australia and estimate that it
is at least 50 million years old. You gather a crew of scientists to perform
traditional species sampling of the river as well as metagenomics techniques to
calculate microbial diversity. The results indicate that the river is extremely
diverse - you even get to name a new species of shrimp after yourself! During
one of your many interviews, you are asked to explain the high diversity of the
subterranean river. What hypothesis would you cite? The time hypothesis.
16. Complete
the sentences explaining the relationship between species diversity and
disturbances to the community.
§ Scientist
have proposed that areas with intermediate levels of disturbances will have the
highest biodiversity.
§ In
areas where there are high levels of disturbances, r-selected species will be
favored because they are better dispersers.
§ On
the other hand, in areas where there are low levels of disturbances, K-selected
species will be favored because they are better competitors and can outcompete
other species.
§ When
disturbances such as fires, floods, and droughts, are relatively frequent in a
community, but only intermediate in frequency in any specific area, then both
r-selected and K-selected species will be favored at varying times and
locations within that community increasing the species diversity.
17. Which
of the following scenarios would provide support for the intermediate
disturbance hypothesis?
§ High
species diversity in a bay that is sheltered from the effects of most storms,
but is affected by hurricanes and extreme storm surges.
§ Low
species diversity on a savannah with very frequent fires and periods of high
predation.
18. How
many different kinds of grass grow on the tallgrass prairie? 150
19. According
to the video, what is the heart of the tallgrass prairie ecosystem? Grass
20. In
the tall grass ecosystem, which organisms would likely have a population
explosion if the snakes were eradicated from the area? Meadow lark; Harvest
mouse
21. If
this grassland were converted for agricultural what would be a likely
consequence of this event on the biodiversity of the ecosystem? The
biodiversity would decrease initially due to the removal of the plant species
and then decrease further due to the loss of the animals dependant on the grasslands.
22. Snakes
are one type of predators in this video, but the grasses and other plants in
this video would be also subjected to some type of predation. Harvest mouse;
grasshoppers
23. The
idea that most ecological communities do not have sharp boundaries, but rather
intergrade with one another, is consistent with what concept(s) of community
ecology?
§ Principle
of species individuality; Individualistic model
24. If
you (incorrectly) proposed that tundra, the world's largest land biome,
contains high species richness, your proposal would be consistent with the area
hypothesis.
25. What
is an area of the Earth's surface currently undergoing primary succession? Volcanoes
in Iceland.
26. In
succession, the ability of one species to make the area suitable for another
species is called facilitation.
27. Complete
the sentences explaining how early colonizers can facilitate the colonization
of other species.
§ One
type of primary succession begins after a glacier reatreats leaving rocks and
debris behind but no soil
§ Initially,
mosses and lichens colonize the area and thrive despite the lack of soil. They
are not dependent on a soil substrate and can prosper on barren rocky lands. As
the initial colonizers die and decay, there is a build up of soil and an
increasing amount of nitrogen and other nutrients in the substrate.
§ As
a result of facilitation by the initial colonizers, flowering herbaceous plants
are able to establish. As these species die and decay, the soil depth will
increase and become enriched with nutrients.
§ With
an increase in the soil depth and nitrogen, there is an emergence of r-selected
species, such as the alder trees, which is a fast growing tree species. The
alder has nitrogen-fixing bacteria within its roots, which facilitates its
growth.
§ Then
K-selected species, such as spruce trees, begin to take over and dominate the
faster growing species. The soil composition continues to be modified due to
the break down of the needles from the evergreen trees, allowing the
colonization by hemlock trees.
28. Community
ecology is best defined as the study of how groups of species interact in the
same place at the same time.
29. What
is considered to be the primary method of succession in the marine intertidal
zone? Inhibition.
30. In
1992, mangrove forests along the southern Florida coast and the Florida Keys
were severely damaged by Hurricane Andrew. Up to 94% mortality was recorded in
some areas, with only the shortest individuals surviving. Scientists have
monitored the region and by 2001, the forest canopy had closed and the main
species were rapidly gaining biomass. This is an example of: secondary
succession.
31. What
information is used to mathematically calculate species diversity?
§ Number
of species in the community
§ Relative
abundance of species in the community
32. A
forest community consists of not only the trees and shrubs, but also the
animals and microorganisms. True
33. The
time hypothesis suggests communities diversify with age. True
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