Flashcards in chapter 18 Deck (54)
Removal of a keystone species can cause
a community to collapse
keystones species that affect communities by influencing the structure of a habitat.
the hypothesis that more species are present in a community that experiences occasional disturbances than in a community with either frequent or rare disturbances.
Intermediate disturbance hypothesis
When disturbances are rare, populations
grow until resources are scarce, and competitively superior species become dominant
When disturbances are frequent, habitats
typically support a small number of species that are adapted to disturbances.
When disturbances occur at an intermediate frequency,
both types of species can persist
a linear representation of how different species in a community feed on each other.
a complex and realistic representation of how species feed on each other in a community.
a level in a food chain or food web of an ecosystem.
the autotrophs that convert light energy and CO2 into carbohydrates through photosynthesis.
a species that eats producers.
a species that eats primary consumers
a species that eats secondary consumers
a species that feeds at several trophic levels.
within a given trophic level, a group of species that feeds on similar items (e.g., guilds of leaf eaters); members of the group are not necessarily related
an interaction between two species that does not involve other species
The direct effect of one species often sets off a chain of events that
affect other species in the community
an interaction between two species that involves one or more intermediate species.
indirect effects in a community that are initiated by a predator.
Indirect effects can occur
when the abundances of trophic groups are determined by the amount of energy available from producers
when the abundances of trophic groups are determined by the existence of predators at the top of the food web
If food webs have three trophic levels, top-down control by predators would
reduce the abundance of herbivores, leading to an increase in vegetation.