Chapter 45: Ecological Communities Flashcards
community
group of species that coexist and interact with one another within a defined geographic area
species composition
the particular mix of species in a community and the relative abundances of those species
True or false: species composition varies along environmental gradients
true
transect
a straight line used for ecological surveying
habitat structure
characteristics of the surfaces and the horizontal and vertical distribution of objects
succession
the relatively predictable way species replace one another after a change in environment
ecological transition
change to a different community after some types of disturbances
niche
set of environmental tolerances of a species, which define where it can live and the way in which a species obtains energy and materials and its pattern of interaction with other species in the community
trophic interactions
consumer-resource interactions cause energy and materials to flow through a community
primary producers
photosynthetic organisms that manufacture the carbs that fuel their metabolism
autotrophs
create their own food
heterotrophs
obtain energy by breaking apart compounds made by other organisms
Primary consumers
hetertophs that eat primary producers
Secondary consumers
heterotrphs that eat primary consumers
also called primary carnivores
tertiary consumers
secondary carnivores
eat primary carnivores
trophic levels
feeding positions (primary producers, consumers)
Omnivores
feed from multiple trophic levels
Decomposers
detritivores
feed on waste products or dead bodies
responsible for the recycling of materials
break down organic into inorganic
food web
Diagrams that show the flow of energy through trophic interactions
Gross Primary Productivity (GPP)
the total amount og energy that primary producers capture and convert into chemcial energy during some period of time
Net Primary Productivity
the energy contained in the tissues that primary producers have produced in an interval of time
ecological efficiency
how much energy gets converted into biomass
trophic cascade
ripple effects that cross trophic levels caused by consumer-resource interactions
ex. Yellowstone National Park
no wolves—-> lots of elk
lots of elk —-> no new aspen trees
Lots of elk—-> hurt streamside willows —> beavers almost go extinct locally
wolves come back, less elk, more aspen, willows regrow, more beavers
species diversity
made up of two components
species richness and species evenness
Species richness
the number of species in a community
Species Evenness
distribution of species abundances
effect of sampling as effect of diversity on community function
more species, more likely to have some that have a strong influence on output
Niche complimentarity
Communities that contain more species may be better able to use all available resources because they are more likely to include species that have complimentary niches
Theory of island Biogeography
offshore island only gains species if they colonize from elesewhere
the rate at which new species arrive on an island must decline as the island fills– as island fills up, many new individuals are from species already there
overall rate at which species lost– extinction rate– must increase as idland fills with species
number of species on an island (species richness) stops changing when colonization rate = extinction rate
ecosystem services
things that ecosystems do
