Chapter 16 Species Abundance and Diversity Flashcards
Groups of species that live in a defined area and interact with each other are termed a(n) ______.
community
All of the fish, invertebrates, and algae living in the upper reaches of a stream would constitute a(n) ______.
community
Which are components of a community’s structure?
the relative abundances of species
the kinds of species present
the number of species present
A group of organisms that exploit resources in a similar way is termed a(n) ______.
guild
Plants that are described as a vine would belong to the same ______.
life-form
Some ecosystems have many thousands of species, making it difficult to study the contribution of each species to the functioning of a community. Therefore, scientists may study the effects of groups of organisms on community structure by placing them into ______.
guilds
As a general rule in a community, very few species are ______.
very rare
very abundant
A scientist who is studying a species’ richness as well as the relative abundances of different species in a community is determining ______.
community structure
One of the most ubiquitous patterns found in communities is that ______.
most species are moderately abundant
very few species are rare
few species are very common
Stream invertebrates that eat or “shred” terrestrial plant material would belong to the same ______.
guild
The community distribution plot of a lognormal distribution is ______.
bell shaped
The structure of a plant combined with its growth dynamics determines its ______.
life-form
Species of plants with a higher percent cover (top graph) and species of forest birds with higher numbers of individuals (bottom graph) are both ______.
uncommon
By studying plant life-forms, scientists can ______.
reduce the number of species they are studying to better understand the community structure
Imagine a community consisting of approximately 100 species. Considering the patterns of species abundances, one would expect to find ______.
very few of the species to be very abundant
A general trend when sampling is that the more you sample, the
more species will be collected.
In a typical community, most species will be ______.
moderately abundant
When the number of individuals in a community are plotted by the number of species, the typical result is a(n) ______.
lognormal distribution
Species diversity is based on which two factors?
the number of species in a community
the relative abundance of species in a community
Based on the figure illustrating lognormal distributions, what do forest birds (bottom) and desert plants (top) have in common?
Very few species are very rare.
Most species have moderate coverage or abundances.
Very few species are abundant
The total number of species within a community is known as the ___.
species richness
When sampling species richness in a community,
the common species will typically be found in small samples.
The relative abundance of species in a community is known as the ______.
species evenness
Species diversity includes the number of ______.
species in a community
Which community would have the higher species diversity?
a community with 20 species with high species evenness
When calculating the species diversity using the Shannon-Wiener index, the ______.
proportion of the ith species is multiplied by the natural log of the proportion of the ith species
Species richness is best defined as the ___.
number of species in a community
A community with an H’ = 0 would have ___.
only one species
Species evenness is also known as the ______.
relative abundance
To view important components of a community such as evenness and richness, ___.
a rank-abundance curve is plotted
In a community with very low species evenness, one would expect to encounter
the same species many times before finding additional species.
If two communities had the same species richness, but the rank-abundance curve for community A was much steeper than community B, then community
B has a higher species diversity.
Sampling a small community revealed the following distribution of species: species A: 100 individuals, species B: 60 individuals, species C: 40 individuals, and species D: 2 individuals. Calculate the species diversity of this community using the Shannon-Wiener index (H’).
H’ = 1.075
The number of species (S) is 4. The total number of individuals is 202 (100+60+40+2). For species A its proportion (Pi) equals 0.495 (100/202). Thus logePi = −0.7031. So the value for species A is −0.3480 (0.495 ×−0.7031). Repeat this and sum the number for all the species and then apply the negative sign in front of the equation to that sum total (−1.075) and get the answer of 1.075.
A rank-abundance curve with a steep curve is indicative of a community ______.
dominated by a few abundant species and lower species richness
Which of the following communities would have the highest species diversity?
H’ = 3.24
At similar latitudes, community A has many more species than community B. What is one possible explanation for this observation?
Community A has a higher habitat heterogeneity than community B.
The value of a rank-abundance curve lies in its ability to ______.
visually portray species richness and evenness in a two-dimensional graph
MacArthur (1958) found that warbler diversity was correlated with ______.
foliage height
Which community would have the highest species diversity?
A community with high species richness and an abundance curve with the lowest slope.
In forest communities, the foliage height diversity varies with ______.
species evenness
species richness
Generally, there is a(n)
______ relationship, or correlation, between environmental complexity and species diversity.
positive
A rank-abundance curve with shallow curve is indicative of a community ______.
with high species evenness
If community A is more complex than community B, then one might expect community ______.
A to have higher species diversity
Animal diversity in terrestrial communities is positively correlated with ______.
plant diversity
Based on studies by MacArthur in the 1950s, communities with more complex forests ______,
contained more species of warblers than other plant communities
Based on Tilman’s work in 1977, the ratio of essential nutrients in communities can determine ______.
whether two species can coexist or exclude each other
In forest communities, environmental complexity can be determined by ______.
foliage height diversity
Tilman demonstrated that Asterionella can exclude Cyclotella when the ratio of ______.
silicate to phosphate is high
Based on the figure, it can be seen that a general trend in ecological communities is for species diversity to increase with ______.
higher environmental complexity
If one knows the nutrient requirements of a plant, then one can begin to define its ______.
niche
Varying nutrient levels in a lake ______.
create environmental complexity leading to higher phytoplankton diversity
High plant diversity is often correlated with ______.
high animal diversity
Nutrients in lakes and terrestrial communities ______.
can vary over small spatial scales leading to plant habitat heterogeneity
Tilman’s work in 1977 showed that some diatoms can coexist when ______.
the ratios of essential nutrients were correct
In tropical forest communities, plant diversity is ______.
very high
Based on Tilman’s 1977 work, two similar species of diatoms can coexist when the ratio of ______.
silicate to phosphate is low
The niches of plants and algae can be defined by ______.
physical characteristics such as moisture
their nutrient requirements
chemical characteristics such as pH
Which of the following are soil characteristics that are directly important to plants?
pH
depth to the ground water
type of soil (sand or clay)
Nutrients in a lake such as nitrates and silicates ______.
can vary independently of each other over small spatial scales
Studies by Jordan (1985) showed that in tropical Amazon forests, a change of elevation greater than 2 m above nearby streams would have ______.
sandy well-drained soils that can cause water stress in plants
In abandoned agricultural fields, nutrients and moisture ______.
do not necessarily correlate with each other, creating habitat heterogeneity and leading to greater plant diversity
In a tropical forest, a particular area may have ______.
many unique plant communities
In tropical forest communities the distribution of plant communities are strongly influenced by ______.
soil characteristics
In a tropical forest, changes as small as 1 m in elevation have ______.
large effects on plant communities due to changes in water availability
In aquatic ecosystems, plant and algal diversity decline with ______.
Plant and algae diversity decline with increasing nutrient availability
In the Park Grass Experiment, the rank-abundance curves have become steeper over time, indicating ______.
a loss of species diversity
Lilleskov and his colleagues found that acid-tolerant ectomycorrhizal fungi are dominant when soil nitrogen levels are ______.
high and the pH is low
As nutrient levels increase in aquatic communities, plant ______.
and algae diversity decrease
When environmental conditions remain relatively the same over a time period, the community is said to be in ______.
equilibrium
There are many definitions of disturbance; however, most them have which of the following in common?
They are discrete physical events.
They allow for the establishment of new individuals or colonies.
They remove individuals or biomass
According to White and Picket, disturbances caused by disease, predation, or human activities would be classified as ______.
biotic factors
Based on the figure illustrating the effect of fertilizing and plant diversity, it can be seen that plant diversity has ______.
decreased over time due to fertilizer use
The intermediate disturbance hypothesis predicts that ______.
the highest level of species diversity is found in communities with continually changing conditions
Under conditions of low nitrate availability, Lilleskov found that fungal communities are ______.
comprised of species specialized in nitrogen uptake
In a community that is in equilibrium, the stability is maintained by ______.
opposing forces
Very low levels of disturbance will ______.
reduce species diversity because only the best competitors will survive
A discrete event that removes individuals or biomass and creates space for new individuals to become established is known as ______.
a disturbance
Abiotic forces of disturbance would include ______.
fire
flooding
Species diversity is highest with an intermediate level of disturbance because ______.
many species can colonize a community, but disturbance will prevent any one species from becoming dominant
Communities with the highest species diversity may be associated with ______.
moderate amounts of disturbance that create constantly changing conditions
Algae and marine invertebrates living on medium-sized boulders experience an intermediate level of disturbance. From this it could be predicted that they would have ______.
the highest level of species diversity compared to small and larger boulders
Very high levels of disturbance will ______.
reduce species diversity because few species will be able to survive the frequent and intense disturbances
Along the intertidal zone, the most frequently disturbed boulders supported ______.
one or a few species that were adapted to the high levels of disturbance
Sousa’s work demonstrates that disturbance ______.
may allow multiple species to coexist because the disturbance prevents competitive exclusion
The highest rate of species diversity is often associated with ______.
an intermediate level of disturbance that prevents competitive exclusion
The intermediate disturbance hypothesis predicts that ______.
the highest level of species diversity is found in communities with continually changing conditions
In temperate grasslands, disturbances can include ______.
grazing
fire
trampling
Algae and marine invertebrates living on smaller boulders experience a higher frequency of disturbance; from this it could be predicted that ______.
species diversity would be lower on these boulders
Prairie dogs create disturbance in a grassland by ______.
grazing on the plants creating bare ground
creating burrows and depositing soil into mounds
The highest rates of species diversity found among boulders in the intertidal zone were found in areas of ______ disturbance.
intermediate
The Lotka-Volterra models predict that ______.
two species cannot coexist indefinitely when using the same resources unless disturbances occur
Prairie dogs increase species diversity by ______.
creating a patchy environment with an intermediate level of disturbance
The activities of prairie dogs help to increase plant diversity by ______.
creating bare patches of ground that facilitate colonization
One of the most important and ubiquitous source of disturbance in temperate grasslands comes from ______.
burrowing mammals
Perhaps the most important source of disturbance in temperate grasslands historically came from ______.
prairie dogs
True or false: Human-caused disturbance such as deforestation would be considered an abiotic factor.
false
In temperate grasslands, plant diversity is highest where ______.
prairie dogs create a patchy environment
Prairie dogs create an intermediate level of disturbance that increases species diversity by ______.
allowing good colonizers and good competitors to coexist
According the IUCN in 2007, the most serious threat to species diversity is ______.
habitat loss
Avian diversity has been found to be highest in ______.
golf courses
Human disturbance is widespread and comes in many forms, including ______.
increased urbanization
air and water pollution
removal of forest
Studies in Ohio and California, showed that increases in land use intensity led to ______.
a decrease in woodland bird species
Worldwide urbanization has led to ______.
a homogenization of the global biota
Human disturbance is a major threat to diversity because it ______.
can be widespread and or extreme
Based on several surveys by Blair in 2004, avian diversity was highest in areas with ______.
an intermediate level of disturbance
Increases in land use intensity has led to ______.
the spread of already widespread and non-native birds species
As towns and cities continue to expand, ______.
the differences in biodiversity between regions will be decreased
