Ch 54 B Flashcards
_______ are those that are most abundant or have the highest biomass
Dominant species
_______, typically introduced to a new environment by humans, may become dominant because they lack natural predators or parasites
Invasive species
_______ exert strong control on a community by their ecological roles, or niches (not dominant)
Keystone species
How do dominant species and keystone species differentiate
keystone is less abundant
_______ (or “foundation species”) cause physical changes in the environment that affect community structure
Ecosystem engineers
What are the two models regarding trophic influence
1) bottom-up model
2) top-down model
What is another name for the top- down model?
green world hypothesis
Explain mesopredator release
Where absence of top predator (wolf) leads to mesopredator abundance (coyote)
Deliberate alteration of an ecosystem by adding or removing species, especially predators.
biomanipulation
F. E. Clements, argued that plant communities had only one state of equilibrium, a _______, controlled by climate
climax community
A. G. Tansley argued that _______ in abiotic conditions created many _______ stable communities within a region
variation; possible
H.A. Gleason viewed communities as _______ assemblages of species with similar abiotic requirements
chance
A _______ is an event that changes a community, removes organisms from it, and alters resource availability
disturbance
The _______ describes communities as constantly changing after disturbance
nonequilibrium model
What are the 3 types of disturbances and what do they result in?
1) low level: allow dominant species
2) intermediate: greatest diversity
3) high level: exclude slow-growing species
_______ is the sequence of changes in community composition following a disturbance
Ecological succession
What are the 2 types of ecological successions?
1) primary succession
2) secondary succession
_______ occurs where no soil exists when succession begins
Primary succession
On the glacial moraines, _______ species facilitate later arrivals by increasing soil nitrogen content
pioneer plant
describe seral stages and facilitation
seral stage -> facilitation -> seral stage
_______ begins in an area where soil remains after a disturbance
Secondary succession
_______ and _______ are two key biogeographic factors that affect the species diversity of biological communities
Latitude and area
Species richness is especially great in the _______ and generally _______ in a gradient toward the poles
1) tropics
2) declines
Two main climatic factors correlated with biodiversity in terrestrial communities are _______ and _______
sunlight and precipitation
_______, the evaporation of water from soil plus transpiration of water from plants
evapotranspiration
_______ is the measure of potential water loss, assuming water is available
Potential evapotranspiration
Evapotranspiration and potential evapotranspiration are _______ in the warm, wet conditions of the tropics
higher
_______ correlates with evapotranspiration and potential evapotranspiration
Species richness
The _______ quantifies the idea that, all other factors being equal, a larger geographic area has more species
species-area curve
Robert MacArthur and E.O. Wilson developed a method for predicting the species diversity on islands called the _______
island equilibrium model
As the number of species on an island increases, immigration _______ and extinction _______
decreases; increases
On a smaller island what happens to number of species, immigration, and extinction?
number of species: less
immigration: less
extinction: more
On a larger island what happens to number of species, immigration, and extinction?
number of species: more
immigration: more
extinction: less
On Islands closer to the mainland what happens to immigration, and extinction?
immigration: more
extinction: less
On Islands farther to the mainland what happens to immigration, and extinction?
immigration: less
extinction: more
An equilibrium will be reached where the rate of _______ is equal to the rate of _______
immigration; extinction
Community structure is universally affected by _______, which include disease-causing microorganisms, viruses, viroids, and prions
pathogens
Pathogens can be particularly _______ in a new habitat
virulent
