changes in species interactions lead to long term changes in the characteristics of populations
intraspecific competition
competition that occurs between members of the same species
interspecific competition
individuals from different species use the same limiting resources
comsumptive competition
occurs when individuals consume the same resources
preemptive competition
exists when one species makes space unavailable to other species
overgrowth competition
happens when one species grows above another
chemical competition
takes place when one species produces toxins that negatively affect another species
territorial competition
arises when a mobile species protects its feeding or breeding territory against other species
encounter competition
occurs when two species interfere directly for access to specific resources
niche
the range of resources that the species is able to use or the range of conditions it can tolerate
competitive exclusion principle
it is not possible for species with the same niche to coexist
asymmetric competition
one species suffers a much greater fitness decline than the other species does
symmetric competition
each of the interacting species experiences a roughly equal decrease in fitness
fundamental niche
combination of resources or areas used or conditions tolerated in the absence of competitors
realized niche
the portion of resources or areas used or conditions tolerated when competition occurs
niche differentiation
resource partitioning
character displacement
change in species traits
mimicry
when one species closely resembles another species
mullerian mimcry
when harmful prey species resemble each other
batesian mimicry
harmless species resemble dangerous species
inducible defenses
defensive traits that are produced only in response to the presence of a predator
prey have a larger... growth rate
intrinsic
predators play a role in ..... growth of prey populations
density dependent
meta analysis
a study of studies
why dont herbivores eat more of the food available on land
herbivores could be kept in check by predation or disease
plant tissues could offer poor or incomplete nutrition
plants could defend themselves against attack
top down control hypothesis
herbbivore populations are limited by predation and disease
poor nutrition hypothesis
plants are a poor food source in terms of the nutrients they provide for herbivores - plant tissues have less that 10 percent of the nitrogen found in animal tissues
plant defense hypothesis
plants defend themselves effectively enough to limit herbivory
communities are a product of
chance and history and predators
keystone species
has a much greater impact on the surrounding species than its abundance and total biomass would suggest
disturbance
any event that removes some individuals or biomass from a community
biomass
total mass of living organisms
the impact of disturbances is a function of three factors
the type of disturbance
its frequency
its severity
primary succession
occurs when a disturbance removes the soul and its organisms as well as organisms that live above the surface
secondary succession
occurs when a disturbance removes some or all of the organisms from an area but leaves the soil intact
early successional communities
are dominated by species that are short lived and small and that disperse their seeds over long distances
late successional communities
are dominated by species that tend to be long lived, large, and good competitors for resources such as light and nutrients
successional pathway
the specific sequence of species that appears over time
weed
a plant that is adapted for growth in disturbed soils
facilitation
takes place when the presence of an early arriving species makes conditions more favorable for the arrival of certain later species by providing shade or nutrients
tolerance
means that existing species do not affect the probability that subsequent species will become established
inhibition
occurs when the presence of one species inhibits the establishment of another
species richness
a simple count of how many species are pesent in a given community
species diversity
a weighted measure that incorporates a species relative abundance as well as its presence or absence
productivity
the total amount of photosynthesis per unit area per year
intermediate disturbance hypothesis
regions with a moderate type, frequency, and severity of disturbance should have high species richness and diversity