Final Exam Flashcards
Community
association of interacting species inhabiting some defined area
community ecology
study of collective properties in the structure of multispecies biological assemblages
Issues of community definition
Co-occurrence: Minimum property of community; species co occur
Recurrence: same group of organisms will occur with the same species
Communities tend toward dynamic stability: stable around given point
one view of a community: Individualistic school
only co-occurrence needed
collection of populations with similar environmental requirements
abstraction of continuously varying vegetation
Superorganism school
tightly coevolved in evolutionary time
important in ecological time
Hypotheses for higher species richness in tropics
- Time theory hypothesis: rate of evolution higher
- Competition Hypothesis: time for evolution to have occurred undisturbed is higher
- Colonization hypothesis: rate of colonization after glaciation limiting in temperate zone
- Climate stability hypothesis: Tropics less seasonal, more constant food resources, niches, specialization
- Spatial heterogeneity: high richness with more habitats
- Predation hypothesis: greater species specific predation
- Productivity hypothesis: productivity increases more levels in web
species richness
number of species in a defined area
Species diversity
the number of different species present in an ecosystem and relative abundance of each of those species.
species richness and equitability
more evenly distributed= more diversity
Community structures
absolute and relative abundance of species in a community
3 major structuring forces of communities
interspecific competition , predation, disturbance
keystone species
species whose activities control structure of food web
keystone predator
eats competitively dominant prey and controls community structure
psistar starfish
Disturbance
Any relatively discrete event in time that disrupts ecosystem, community or population structure and changes resources, substrate availability, or the physical environment
Intermediate Disturbance Hypothesis (IDH)
Highest species richness when disturbance is in the middle; not too much or too little disturbance
succession
non seasonal, directional, and continuous pattern of colonization and extinction on a site by a population of species
climax community
vegetation formation resulting after many years of development
endpoint of succession
Predictable , local extinction
3 successional processes
Facilitation, Tolerance, inhibition
Facilitation successional process
organisms make environment for other organisms to come in and makes it less favorable for itself
Facilitation -glacier bay Alaska
when glaciers move, it leaves behind rock, moss breaks down rock converting it to soil
- moss outcompeted by fireweed, willows, alder trees bringing in nitrogen for plants
facilitation in Poorly drained soils
Invasion of sphagnum moss in areas of poorly drained soils in early stages of forest
- acidifies water so trees die
- creates bogs
Tolerance
Later species outcompete earlier ones but early species don’t make environment more favorable for later species
species sequence is from colonization ability, growth, competitive ability
primary v secondary succession
primary: occurs on bare sediments
- glacier retreat, lava flow
secondary: existing vegetation disturbed and replaced
- fire
tolerance- sand dunes
grasses established after blowout
grasses outcompeted by willows, pines, oak forests
Inhibition
Each species inhibits colonization by subsequent species
- species at site first will hold it until external force disrupts it
External force disrupting system is required for succession to proceed
- Autogenic: within system
- Allogenic: outside system
Tolerance- rocky intertidal
Algal density highest for boulders of intermediate size which require intermediate force to be overturned
Stable environment will be unchanging
Unstable environment evoke successional change
Factors that determine biome
Annual precipitation
temperature
Temperate deciduous forest
Cold winters, local variations, abundant understory
more species rich than coniferous
Coniferous
short humid summers, long cold winters, large temp variation
many predators
- lynx, bobcat, wolverine
prey
- hare
Temperate Rainforest
lot of rainfall, seasonal variation
mixture of conifers and deciduous
Tundra
many lakes, bogs
low precipitation
low biological diversity
simple vegetation
primary consumers
plants who do photosynthesis
secondary consumers
herbivores who eat primary consumers
Grasslands
Enough precipitation to support grasses not trees
tall grass in humid wet environments and short grasss praries
fires
mice, grasshoppers, buffalo
Savanna
Grasslands with scattered trees
less rainfall
dry summer wet winter
fire
high biodiversity
shrubland
Short densely branching shrubs
long dry hot summers
mild rainy winter
fire
Deserts
Drought year round– less than 10 in rain/year
Hot deserts in tropic of cancer and capricorns
cold deserts
burrowing animals, not many plants
rain shadow effect
as weather from the ocean travels towards a mountain, it rains and cool air descends creating a desert in the region of a rain shadow
Types of deserts
rain shadow effect
cold ocean desert
Landlocked desert
Tropical rainforest
a lot of precipitation
high species richness
tall straight trees
medicines
many insects
aquatic v marine
aquatic: freshwater
marine: saltwater
Lentic v lotic
lentic: bodies of water without current
lotic: bodies of running water
limnology
inland bodies of water
temporary ponds
only around in spring
water retained for short period of time when snow melts
springs
spring fed pond: springs come up to surface
geothermal pools: very hot with bacteria living
volcanic lake
calderas: empty volcanoes fill with water
Tectonic lakes
formed by tectonic plate shifts
Glacial lakes
formed by receding glaciers
kettle lakes
Seasonality of lakes
Spring: isothermal (same temp 4C throughout) and lake turnover- mixes
Summer: Wind and sun warms surface water and there is a stratified lake zones
- Warmer on surface, cooler as you get deeper (4C)
Fall: lake turnover with wind, cooler temps mixes epilimnion and hypolimnion isothermal
Winter: with colder temps, surface water freezes, and warmer deeper
Lake zones in Summer
Epilimnion- warmer surface, oxygen rich
Metalimnion - thermocline
Hypolimnion- cooler, oxygen poor
– decomposition dominates
dimictic lakes
mix twice a year- spring and fall
otherwise ice would form on bottom
limnetic zone and organisms
open area of water that light can penetrate down
primary producers:
planktonic: drift in current
- phytoplankton
nektonic: can swim against current
primary consumers: zooplankton
epilimnion: biological material source
hypolimnion: sink for material
profundal zone
deep part of lake with little light
benthic zone
bottom of lake with bottom dwelling organisms
littoral zone
shallower area where light can penetrate to bottom of lake
oligotrophic v eutrophic
Oligotrophic: nutrient (nitrogen, phosphorous) poor
Eutrophic: nutrient rich
- hypereutrophic- too much nutrients
dystrophic: bogs
Human eutrophication
Human activity increasing rate of eutrophication
dystrophic
describes bogs and fens
compensation depth
Where photosynthesis= respiration
bogs
- where they’re formed
wetlands where organic matter accumulation exceeds rate of decomposition
low nutrients
formed where precipitation exceeds evaporation , poor drainage, cool temps
trophic cascade hypothesis
manipulating one level of food web affects other aspects of food web
Algal blooms
oxygen depletion in ponds causes fish to die off
approaches to algal blooms
adding herbicides- kill algae temporarily but lead to cycle
adding zooplankton not cost effective
biomanipulation: controlling lakes by adding to top of food web- fish decrease algae population
Trophic cascade experiment
eradicate invasive rainbow smelt fish population by adding GELIs to keep lake mixed so the fish can’t survive because they only reproduce in cold temps
fens
primarily grasses instead of sphanum moss
not acidic
Succession of lakes
Eventually fill in from bottom by vegetation, plants growing on bottom
Goes from aquatic to terrestrial process
Non seasonal, directional
4 dimensions lotic systems
longitudinal
lateral
vertical
time
longitudinal dimension
upstream to downstream changes expected to see in rivers
pools: deep, slow moving
runs/glides: smooth, fast moving
riffles: shallow, turbulent, fast moving
rapids: steep, coarse substrates, fast moving
lateral dimension
exchange of material from river to terrestrial environment as you go across the stream
wetted channel: portion containing water even during low flow periods
active channel: actively filled with water by average stream flows
riparian zone: outside channel; transition between aquatic environment and upland terrestrial environment denoted by vegetation tolerant to water
floodplain: fluvial surface created by infrequent floods
Vertical dimension
water can move from surface down to sediments of river
water column: water surface to benthic zone
benthic zone: bottom of river
hyporheic zone: below current, transition between surface water flow and groundwater
phreatic zone: below hyporheic zone containing groundwater
time dimension
rivers vary across time and space resulting in constantly changing river shape, size, content
from flooding, erosion, changes to environment
what determined stream types
precipitation and evaporation
stream types
perennial: where precipitation exceeds evaporation; flow year round
intermittent: flow most of the year , dry parts of the year
ephemeral: only flow after rainfall event
watershed
any area of land that intercepts and drains rain through river system
stream order
method of classifying ordering hierarchy natural channels
1st order: smallest headwater stream
2nd order: 2 1st orders together
low order: 1-3 order
mid order: 4-6 order
high order: 7-12 order
Sources of organic matter
autochthonous: originates within stream
allochthonous: originates outside stream
CPOM: coarse particulate organic matter
FPOM: fine particulate organic matter
DOM: dissolved organic matter
Upper reaches (small rivers) abiotic factors
riparian vegetation
1-3 order
P/R <1
CPOM
upper reaches biotic factors
peanut butter cracker hypothesis: organisms eat leaves to get to biofilms
shredders and collectors
dominants fish require high oxygen
middle reaches abiotic
4-6 order
CPOM breaks down into FPOM
P/R >1
autochthonous dominated
middle reaches biotic
collectors and grazers
fish tolerate high temp low oxygen
lower reaches (large rivers)abiotic
large rivers
fpom dominate
p/r<1 causing turbity
lower reaches biotic
more planktonic orgnanisms
collectors
fish tolerant of high temp low oxygen
river continuum concept
predicts characteristic changes from upstream to downstream
human influence on flood
channelization: gets water in and out of area quickly
runoff into channelized streams increases flood frequency
dams:modifies flow regime
electricity, flood control
overland flow
surface runoff; water running over land into stream
when solid are saturated and low permeability
precipitation exceeds soil infiltration rate
impervious surfaces
hydrograph
time it takes to rise from baseflow to maximum discharge to baseflow conditions
storm hydrograph: lag time after peak of storm shorter in urbana areas
effects of urbanization on storm hydrograph
after urbanization
peak higher, shorter lag time
general hydrograph patterns
high in early spring
low in summer
high in fall
rainfall patterns spiky graph
snowmelt patterns smooth graph
Invasive species definition
non native to ecosystem under consideration and
whose introduction causes or is likely to cause economic or enviornmental harm or harm to human health
causes of accidental introduction of invasive species
accidental releases
- aquaculture
- aquarium trade
transportation
- navigation channels
- ballast dumping
range expansion as temps warm
Goby
eat zebra mussels and invertebrates
prefer benthic rocky habitat
spawn many times a year
come in through ballast water
Ballast water management
NOBOB– empty ballast before entering us
this impacts native species and movement of toxic materials from sediments
scenarios of gobys and algae
gobys reduce benthic invetebrates increasing algae
gobys reduce mussels and reduce algae
bioaccumulate v biomagnicifcation
bioaccumulation: materials accumulate in organisms as a result of feeding
biomagnification: materials that are concentrated at higher levels as you go up food web
PCBs
organic contaminants
contaminant of fish
human health problems when consumed in fish
Gobies and PCBs
biomagnification of PCBs evident at highest level of food chain
chironomids– midges
low oxygen water
energentically important-relied on by many birds as food source
eggs must go through dry period
invasive nuisance
2 approaches on how to reduce nuisance midges
Bti - lethal when ingested by insect
STRIKE pellets- flood with juvenile hormone prevents insect from molting to adult
Bti and strike effects
Bti no affect
STRIKE at reduced emergence
Marine derived nutrients (MDN) with salmon
nutrients from marine environment cycled in fresh water system
Salmon egg, sperm, carcass provide nutrients to algae, insect feed on algae, young salmon feed on insects
Eltonian pyramids
Pyramid of numbers– not good way to process
pyramid of biomass– not good to process
pyramid of enegy– cannot be inverted
how salmon affects midges
midges that live on rocks are affected because salmon bring a lot of MDN into freshwater when they spawn
climate change effects
increased sea level, water temps
pH change
climate change effect on migratory birds
disconnect between bird migration (triggered by photoperiod) and insect availability (controlled by temp)
What did bluegill study show
there are habitat linked morphological and behavioral adaptations that make them better at avoiding predators
a limnetic fish in a littoral environment will be subject to more predation because they aren’t as well adapted
Crayfish and worm symbiosis study
Commenslism relationship because crayfish benefit by having worms removing large PM from their gills allowing for better survival
Worms don’t benefit
Hantavirus pulmonary syndrome study
Higher density of infected rodents provides a higher baseline for future infection that can trigger outbreak when next surge in rodent population occurs
kettle lakes
formed by glaciers
