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63 Cards in this Set
- Front
- Back
Number of species in a community |
Species richness |
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Proportion of individuals in a community represented by each species |
Relative abundance |
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Curve that plots relative abundance of each species in rank order from most abundant to least abundant |
Rank-abundance curve |
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Measure of the difference in relative abundances of species in a community |
Species evenness |
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What does the slope represent in a in a relative abundance vs. ranked abundance graph? |
The slope= eveness |
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What does going from left to right represent in a in a relative abundance vs. ranked abundance graph? |
The higher species richness going this way ------> |
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In terms of evenness and richness describe this graph? |
The purple line has more evenness less richness but the green line has less evenness and more richness |
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Which of the following could cause the relative abundance distribution to change as show? |
Decreasing effort at sampling species |
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If you increase resources and increase biomass, what are the two pathways that diversity can take? |
It can either increase because there are more niches, or it can decrease because more competition selects for better competitors |
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What are the five pathways that effect of resource on diversity can have? |
U-shaped, Negative, None, Positive, Hump-shaped |
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Which type of shape seems to have the most positive effect on on diversity? |
Hump-shap[d
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What do experiments that manipulate productivity by adding nutrients to an ecosystem commonly cause? |
A decline in the species richness of producers |
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What is happening in this graph? |
As more resources are added, it becomes negative, thus there is more competition among the plants |
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Why do species richness decline with increases in habitat fertility? |
Competition |
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Why could communities with a higher diversity of habitats increase diversity? |
They should offer more potential niches and higher diversity of species |
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Species whose presence substantially affects the abundance of other species in the community |
Keystone species |
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What is an example of a keystone species and why? |
Pisaster starfish, east mussels, barnacles, limpets and it affects the abundance of other species |
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Graph of Keystone species |
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Keystone species that affect communities by influencing the structure of a habitat |
Ecosystem engineers |
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What do ecosystem engineers do? |
Niche construction |
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Diversity highest when disturbance intermediate |
Intermediate disturbance hypothesis |
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What are some examples of disturbances? |
Fires, floods, tornadoes, land use change |
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Graph of intermediate disturbance hypothesis |
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One linear part of a web |
Food chain |
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organisms that eat at the same levels (same level organisms in a food web) |
Trophic level |
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What are some trophic level examples? |
Producers, consumers, |
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What level has the most biomass in a food web? |
Grassese and the bottom (the producers) |
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Levels of a food web |
Producers at the bottom, then consumers like the red squirrel or snowshoe hare and then the 2 prime consumers like a wolf |
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Food web |
The interactions and relationships among different species and species levels as it relates to food consumption |
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Within a level, species that feeds on similar items |
Guild |
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Levels of food web |
Producers, Primary consumers, secondary consumers, tertiary consumers at the top |
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Chesapeake Bay Food Web Example |
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Interaction between two species that does not involve other species |
Direct effect |
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Interaction between two species that involves one or more intermediate species |
Indirect effect |
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Indirect effects in a community that are initiated by a predator |
Trophic cascade |
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Question: (1) Solid = ? (II) Dashed= ? (III) Red =? (IV) Green = ? |
(I) Direct (II) Indirect (III) = - (IV)= + |
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Proportion of animals in direct vs. indirect effects |
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Indirect effect caused by changes in density of an intermediate species |
Density- mediated indirect effect |
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Indirect effect caused by changes in traits of an intermediate species |
Trait mediated indirect effect |
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What happens in some habitats if you increase spiders? |
Decrease in grasshoppers and an increase in grass |
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Example of how grasshopper behaviors change according to potential predatros |
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Abundances of trophic groups determined by the amount of energy available from producers |
Bottom-up control |
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Abundances of trophic groups determined by the existence of predators at the top of the food web |
Top-down control |
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Another way to describe bottom up |
Producers on up |
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Another way to describe top down control |
From predator down |
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Ability of a community to maintain a particular structure |
Community stability |
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Amount a community resists changes when acted upon by a distrubance |
Community resistance |
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Speed of return of a community to its original state after a disturbance |
Community resilience |
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After disturbance to species composition, new community structure forms and is resistant to further change |
Alternative stable state |
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When does succession occur in a community? |
When species replace each other over time |
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T or F: succession always occurs through different mechanisms |
False, can occur through different ones |
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T or F: Succession always produces a single climax community |
False, does not always produce a single climax community |
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Species composition of a community changes over time |
Succesion |
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A seral community is what? |
is an intermediate stagefound in ecological succession in an ecosystem advancing towards its climax community. In many cases more than one seral stage evolves until climax conditions are attained. |
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Earliest species to arrive at a site |
Pioneer species |
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Final stage in succession |
Climax community |
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What is the first seral stage? |
Bare rock, no soil |
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What is the Final seral stage? |
Stable community composition |
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What is the clearest way to record succession in a community? |
Direct observation of changes over time |
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What is a modern example of observing succession? |
Mt St. Helens from 1980 to now has moved toward its climax plant communities |
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What is an early example of observing succession? |
Krakatu shrinking island boundary |
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a sequence of communities that exist over time at a given location |
Chronosequence |
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What has happened at the dunes at Lake Michigan? |
lakes have lowered, and it has moved closer to climax community |