exam 4 Flashcards
Fitness trade-off
compromises between traits
ex: organisms at the bottom of the ocean can’t live on land
Low population density
More space, resources, finding mates can be difficult
High population density
Finding mates easier, competition
for limited resources
Random dispersion
Occurs when individuals are spaced in a manner that is unrelated to the presence of others
Clumped dispersion
Occurs when individuals are concentrated in specific parts of the habitat
Uniform dispersion
Individuals are more evenly spaced than a random pattern
Results from severe competition
Dispersion
How individuals in a population space themselves relative to one another
Dispersal
Movement of individuals among populations
Model for Populations formula
ΔN /Δt = N(b − d)
ΔN
change in number of individuals in a
population
Δt
change in a given period of time
growth rate formula
r=b-d
instantaneous growth rate formula
dN/dt = rN
Exponential Population Growth
j shape curve
optimal conditions
Carrying Capacity (k)
limits the number of individuals due to a limited amount of resources
Logistic Population Growth
s shape curve
has a carrying capacity
Density-Dependent Factors
biotic
Predation, disease, and competition
Density-Independent Factors
abiotic
fire, weather
Life History Traits
Significant features of an organism’s life cycle that influence survival, growth and reproduction
factors like age at maturity, number of offspring, size at birth
Trade-offs and Life Histories
Organisms have finite resources, leads to trade-offs between survival and reproduction
ex: less offspring= more resources
r selected species
small, short lifespan, many offspring with no parental care
k selected species
long life, large, few offspring with parental care
Commensalism
(+/0) one species benefits, one is unaffected
Competition
(-/-) lowers the fitness of individuals involved
Intraspecific competition
competition between same species
Interspecific competition
competition between different species
happens when 2 species niches overlap
competitive exclusion principle
two species cannot coexist if their niches overlap completely
resource partitioning
reducing interspecific competition by using different parts of a resource
Consumption
(+/-) one organism eats another
herbivory, predation, parasitism
Avoidance
hiding with or w/o camouflage, running
away
Cryptic coloration
coloration to blend in
Aposematic coloration
warning coloration for poison
Batesian mimicry
Resemblance of a dangerous species
Mutualism
(+/+) both organisms benefit
Species richness
number of species
Relative abundance/ species evenness
proportion of each species
Trophic level:
the position an organism occupies in a food chain
“Top-down” control hypothesis
Predation and disease limits herbivore
abundances
“Bottom-up” limitation hypothesis
Limitation to herbivore abundance comes from lower in the food chain
plants provide poor nutrition and are well-defended against herbivory
how much energy is lost between trophic levels
90%
Biomanipulation
ecologists introduce predator species to balance ecosystem
Foundation species
have strong effects due to their large size or high abundance
trees, coral, shrubs
Ecosystem engineers
organisms that cause physical changes in environment that affect community structure.
beavers
Keystone species
important in ecosystems because of their pivotal ecological roles
less abundant
F. E. Clement
argued that plant communities had
only one stable equilibrium
A. G. Tansley
argued that many potential stable communities were possible depending on a combination of environmental influences
intermediate disturbance hypothesis
moderate levels of disturbance promote greater diversity than either high or low levels of disturbance
nonequilibrium model
describes communities as constantly changing after disturbances
Primary succession
succession after new volcanic island or retreating glacier
no soil
Secondary succession
succession after a major disturbance has removed most but not all of the organisms in a community
ex: fire
species-area curve
a larger geographic area should have more species
introduction of arctic fox onto islands in Alaska
resulted in a transformation from grassland to tundra ecosystem
energy vs chemicals in ecosystems
energy flows in and out
chemicals cycle through
first law of thermodynamics
energy can’t be created or destroyed, only transformed
how does energy enter ecosystems
as solar energy
second law of thermodynamics
every exchange of energy increases the entropy of the universe and energy is lost as heat
law of conservation of mass
matter can’t be created or destroyed
what trophic level plays a key role in chemical cycling
decomposers
water cycle reservoirs
97% ocean, 2% ice, 1% lakes and rivers
water cycle key processes
Evaporation, transpiration, condensation, precipitation, runoff
Carbon Cycle: Forms available to life
photosynthesis from plants
Carbon Cycle: Reservoirs
Fossil fuels, soils, sediments, solutes in oceans, plant and animal biomass, the atmosphere
Carbon Cycle: Key processes
photosynthesis, cellular respiration, volcanoes, burning wood and fossil fuels
Carbon Cycle importance
organic molecules
Nitrogen Cycle importance
nucleic acids, Amino acids, proteins
Nitrogen Cycle: Forms available to life
plants use ammonium and nitrate
bacteria use nitrite
animals use organic forms
Nitrogen Cycle: Reservoirs
atmosphere, soils, sediments, water, organisms
Nitrogen Cycle: Key processes
fixation, nitrification, denitrification, industrial fertilizers, legume crops, gas emissions
Phosphorous Cycle Biological importance
phospholipids, Nucleic acids, and ATP
Phosphorous Cycle: Forms available to life
phosphate
Phosphorous Cycle: Reservoirs
sedimentary rocks in ocean, soil, ocean, organisms
Phosphorous Cycle: Key processes
Weathering of rock, leaching into water, incorporation into organic molecules, excretion by animals, and decomposition
what do restoration ecologists do
initiate or speed up the recovery of degraded ecosystems
Two key strategies in restoration
bioremediation and biological augmentation
Kissimmee River, Florida
turned into a straight canal, dried wetlands and threatened fish and bird populations
Succulent Karoo, South Africa
overgrazing by livestock damaged ecosystem
Maungatautari, New Zealand
introduced invasive species
Coastal Japan
Destruction of coastal seaweed and seagrass beds threatened fish
Bioremediation
uses organisms—typically prokaryotes, fungi, or plants—to detoxify ecosystems
Biological augmentation
uses organisms to add essential materials to a degraded ecosystem
ex: adding nitrogen fixing plants or mycorrhizal fungi
