Communities and Ecosystems Flashcards
define a population
a group of interacting individuals of a particular species
define a biological community
populations living close enough for potential interaction
community ecology is concerned with…
factors that influence the species composition and dynamics of communities
define interspecific interactions
relationships with different species in the community that greatly affect population structure and dynamics
list 5 examples of interspecific interactions
- competition
- mutualism
- predation
- herbivory
- parasites and pathogens
competition occurs when
populations of two different species compete for the same limited resource
define an ecological niche
the sum of an organism’s use of biotic and abiotic resources in its environment
interspecific competition occurs when the niches of two populations…
overlap and both populations need a resource that is in short supply
in general competition lowers the ________ _______ for competing populations
carrying capacity
mutualism is when
both populations benefit
a mutualistic relationship often evolves to be
obligatory symbionts
example of mutualism
photosynthetic algae and reef-building corals
describe predation
the predator kills and eats the prey
adaptations in prey populations for prey avoidance includes
- camouflage
- mechanical defenses
- chemical defenses
describe herbivory
an animal that consumes plant parts or algae
plant defenses against herbivores include
- spines and thorns
- chemical toxins (sometimes used in the medical field)
Some plants chemical defense causes….
abnormal development in insects that eat the plant
Some herbivore-plant interactions illustrate…
coevolutions
define coevolution
a series of reciprocal evolutionary adaptations in two species
examples of coevolution include..
- monophagy (butterflies that only eat a specific leaf)
- chemical incorporations (toxic butterflies or plants with egg spots)
describe parasitism
host plants/animals are victimized by parasites or pathogens
non-native pathogens can have…
give an example
rapid and dramatic impacts
-American chestnut being devastated by the chestnut blight protist
define trophic structure
a pattern of feeding relationships consisting of different levels
a food chain is known as
the sequence of food transfer up the trophic levels
producers are
autotrophs that support all other trophic levels
consumers are…
heterotrophs
herbivores are..
primary consumers
secondary consumers typically eat
herbivores
tertiary consumers typically eat
secondary consumers
quaternary consumers typically eat
tertiary consumers
define detritus..
the dead material produced at all the trophic levels
detritivores derive their energy from…
detritus
decomposers are mainly..
prokaryotes and fungi
decomposers have ______ _______.
secretion enzymes
define decomposition
the conversion of organic molecules into inorganic molecules through the digestion of decomposers
define a food web
a network of interconnecting food chains
what is a more realistic view of the trophic level of a community?
a food web
species diversity is defined by…
- species richness
- relative abundance
species richness is the
of different species in a community
relative abundance is the…
proportional representation of a species in a community
low species diversity is characteristic to most
modern agricultural ecosystems
high diversity areas have lots of species at
intermediate abundance
what is a way to measure the species diversity
- absolute richness
- Shannon entropy index
species diversity can often drive other
ecological processes/ measures
define the edge effect
the greatest biological diversity occurs where two ecosystems meet
describe keystone species
one whose impact on its community is larger than its biomass; occupies a niche that holds the rest of its community in place
examples of keystone species
- sea otters and kelp
- urchins and orcas
- gopher tortoises in longleaf pine forests
disturbances are events that..
damage biological communities and include storms, fires, floods, drought, human activity
small-scale disturbances often have a…
positive effect
ecological succession is a…
transition in species composition of a community
primary succession is the…
gradual colonization of barren rocks
secondary succession occurs after…
a disturbance has destroyed a community but left the soil intact
characteristics of invasive species..
- have been introduced to non-native habitats by humans
- established at the expense of native communities
- can spread from introduction site
invasive species can become
naturalist- self-sustaining
examples of invasive species
- fire ants
- burmese pythons in South Florida
ecosystem ecology emphasized
energy flow and chemical cycling
an ecosystem consists of
- all organisms in a community
- organisms’ interaction with abiotic environment
energy flow moves…
through the components of an ecosystem
chemical cycling is the…
transfer of materials within the ecosystem
define primary production
the conversion of solar energy to chemical energy by photosynthesis
gross primary production is the
total amount of primary production during a given time period
define net primary production
the amount of new organic material added to an organism in a given period
primary production varies in
different environments
only about ___ of available sunlight is converted to organic compounds by plants
3%
only about ___ of the energy stored at each trophic level is available to next level
10%
when humans eat grain or fruit we are…
primary consumers
when humans eat beef we are
secondary consumer
when humans eat fish, trout, salmon we are
tertiary/ quaternary consumers
chemicals are cycled between…
organic matter and abiotic reservoirs
ecosystem are supplied with a constant influx of energy from
the sun and Earth’s interior
There are no extraterrestrial sources of chemical elements except for
meteorites
life depends on…
the recycling of chemicals
biogeochemical cycles include what 3 things
- biotic components
- abiotic components
- abiotic reservoirs
biogeochemical cycles can be
local or global
list 3 examples of biogeochemical cycles
- carbon
- phosphorus
- nitrogen
carbon is the..
major ingredient of all organic molecules
where is the reservoir for carbon?
in the atmosphere
carbon cycles…
globally
carbon resides in plant and animal
biomass, fossil fuels, soils, sedimentary rock, and as dissolved carbon
where does carbon enter the ecosystem?
through wood and fossil fuels
the phosphorus cycle depends on…
the weathering of rock
Organisms usually require phosphorus in the form of…
phosphate ion PO4 ^3-
phosphorus is an ingredient of
- nucleic acids, phospholipids, ATP,
- as mineral component of bones and teeth
Phosphorus DOES NOT have a ______ ______ compared to carbon cycle.
atmospheric component
phosphates are transferred from terrestrial to aquatic ecosystems more rapidly than…
they are replaced
why is the phosphorus cycle considered “local”?
there’s no atmospheric component
Nitrogen is an ingredient to
proteins and nucleic acids
nitrogen is essential to the
structure and functioning of all organisms
nitrogen can be described as what ______ and _______ as a plant nutrient.
crucial
limiting
What are nitrogen’s 2 abiotic reservoirs?
- the atmosphere (80%)
2. soil
What are the 3 types of bacteria?
- ammonifying bacteria
- nitrogen fixing bacteria
- nitrifying bacteria
what charge do ammonium and nitrate have?
a positive one
nitrogen fixation converts…
N2 to compounds of nitrogen that can be used by plants
describe how denitrifying bacteria works
under low oxygen conditions soil bacteria strip O from NO3- releasing N2
in aquatic ecosystem primary production is limited by
-low nutrient levels of phosphorus and nitrogen
define eutrophication
excessive richness of nutrients in a body of water
eutrophication results in
- decreased species diversity
- oxygen depletion in body of water
characteristics of eutrophication
- cyanobacteria and dinoflagellates replace native aquatic plants
- outcompete and crash natural ecosystems
- consume oxygen
- produce toxins
eutrophication causes…
oceanic dead zones
Human rely on natural ecosystems to
- supply fresh water and foods
- recycle nutrients
- decompose wastes
- regulate climate/ air quality
examples of ecosystem services include
- wetlands
- natural vegetation
wetlands purpose…
- buffer against tidal waves
- reduce the impact of flooding rivers
- filter pollutants
natural vegetation helps to
- retain fertile soil
- prevent landslides and mudslides
