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112 Cards in this Set
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biosphere collapse
biodiversity loss, loss of pollinators, poor crop production (loss plant species) rich organic soil decomposed, O consumption, drop in atmospheric O |
Ecosystem concept
living things connected with environment, dependent on surroundings (modifies) energy flow/matter link living things with physical environment ecosystem=all organisms/abiotic factors in environment |
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Ecosystem size
entire planet catchment boundaries from continental (amazon) to local (forest) |
Trophic levels
food web, ecosystem structure food chain consist of trophic levels radiation absorbtion-photosynthesis-predation-decomposition-nutrient uptake-transpiration |
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Ecosystem influences. 2 types
states factors interactive controls |
State factors
climate dominant factor (dtermines biomes) parent material (influences soil) topography (controls hydrology, micro climate, soil development) |
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interactive controls
resources (energy, material used by organisms) Modulators (physical/chemical properties) e.g temp, pH disturbances (fire, floods) |
Feedback
+ve (push ecosystems to change) -ve (resist change) |
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How to study
compare ecosystem which differ in potential biota altitudinal transect |
Soil geology
thin film over earths surface, geological/biological process interact within climate region, soils control ecosystem processes |
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Soil, multiphasic system
consists of: organic remains, clay, rock, liquids and gases solids are 50% of volume source of water/nutrients for plants/microbes physcial vegetation support system medium for decomposer organisms |
Rock cycles
mountains are weather, rocks are crushed into sediments sediment move into crush, changed plate collision moves mountains back up |
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Climate, in soil formation
temp/moisture influence rock weathering rates influences development of rocks in soils |
Time
newly exposed geologic substrate has more phosphorus more phosphorus, more organic material over time, more phosphorus absorbed into unavailable forms old soils, less fertile |
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Soil loss
dependent on deposition, erosion and development balance is needed |
Erosion
0.1-1mm over 1000 years variable (steep terrain, high rainfall, lack of vegetation) effects: young soils-reduces soil fertility (removes clay/organic matter) old-renews fertility (removes weathered remnants, exposes new nutirents) |
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Profiles, develop through:
addition-precipitation, organic matter transformations/transfers-humus, hydrous oxides, clays, ions losses-lions, silica |
Weathering
physical: fragmentation, tectonic, abrasion, freeze thaw, roots, fire chemical: acidic/oxidation, dissolved, carbonic acid weathering of primary materials produce secondary materials |
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Leeching
vertical layering of soils downward movement of dissolved minerals, particulate transfer in water |
Soil profiles
O horizon-organic material, litter of dead organisms A horizon-uppermost mineral level, organic matter E horizon- maximum leeching B horizon-iron/aluminium accumulation C horizon-unweathered parent material R-bedrock |
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types:
temperate deciduous coniferous forest grassland tropical rainforest desert |
Soil modulates
water/nutrient availability/cycling texture is key component |
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Soil texture
% of sand, slit and clay different textures determine water saturation level |
Soil water
water saturated-all pores filled with water drains under gravity field capacity-water no longer freely drains permanent wilting point-water no longer moves water holding capacity-difference between field capacity and permanent wilting point |
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Organic matter
dead organism material determines soil development, water holding capacity, nutrient retention food for heterotrophic organisms |
Global energy balance
earths temp varies, keeping energy flow balanced differences in latitudinal variation and seasons |
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Atmospheric circulation
air rises at ITCZ (equator) N or S 30%, forms hadley cell Polar air falls towards equator, meets warmer air returns to poles (polar cell) remains (ferrell cell) coriolis effect-easterlies in tropics, westerlies at mid-latitudes |
Precipitation
greatest with rising air, onshore winds Temp greatest over summer months topography rainfall higher on sea side of mountains |
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Land cover
albedo effect (reflectivity): oceans-low snow/ice-high vegetation-medium soil-dependent on wetness Evapotranspiration: trees transpire ore than grass |
Climate change
dependent on solar input (shorter timescale) changes in eccentricity of orbit season length angle of earths axis to sun |
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Distribution of biomes is related to changes in earths climate
predict climate changes, predict biome changes higher precipitation and temp, richer biome |
Major biomes:
equator-moist rainforest, dry tropical woodland, dry forest mid latitudes-warm temperate, cool temperate, mediterranean high latitudes-boreal, sub arctic, arctic |
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Water
high specific heat capacity, slow temp change states change, considerable energy water held in air increases with temp |
Solar radiation budget
balance between incoming/outgoing radiation Rnet=(Kin-Kout)+(Lin-Lout) K-shortwave L-longwave |
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ecosystem radiation budget
energy partitioning-ecosystem energy absorbed balanced by energy released (soil, atmosphere) Partitioning controls Water budgets-soil filled by precipitation, emptied by evapotranspiration, runoff and drainage |
Water movement
water cycle replace water across ecosystem speed dependent on soil (hydraulic conductivity) and path length |
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Transpiration
water moves from high to low potential energy low partial water pressure in air, loss of water through stomata replaced by uptake from roots |
Root depth
compromise between water and nutrient availability most roots in surface longer lived plants, deeper roots |
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Water flow influences
land use (deforestation) annual rainfall soil composition |
Nutrients
absorbed by plants, returned by decomposition energy cannot by created or destroyed, only recycled matter is recycled pulses (autumn falling leaves, wet season) |
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Nutrients
inorganic: atmospheres, lithosphere, hydrosphere organic: C (organic compounds), N (protein), P (ATP) |
Inputs
Rock weathering- (Ca, Fe, Mg, P, K) Atmospheric- (fixing, N and C), wet/dry deposition Streamwater- flooding |
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Nutrient rentention
determined by clay and humus content, -ve charge of cations provides attraction higher acidity, lower charger, lower fertility |
N fixation
reduction of N catalysed by nitrogenase 16 ATP, one N triple bond bacterium need abundant carbohydrate supply must be anaerobic, O denatures |
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Outputs
loss to atmosphere: respiration, methanogenesis, denitrification, fire Dissolved in stream flow: most nutrients soluble in water |
Specific minerals:
N-atmosphere P, K, Ca etc-rocks S-atmosphere/rocks |
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Phosphorus
not in atmosphere released by weathering, closely linked with soil pH in lakes, held within plankton. dependent on predation rates soluble at low/high pH |
Nutrient uptake
plants prioritsie certian nutrients in lower abundance P and N must remain in balance differences: nutrient input, plant traits (root length/activity) |
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Mycorrhizae
symbiotic relationships between plants and fungal hypahe nutrient exchange increases root absorbance ability |
Nutrient use
tissue production (leaves, roots etc) areas used for metabolism prioritised, nutrients are used up |
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Nutrient use efficiency NUE
net primary productivity/nutrient uptake best where nutrient are limited plants are better at making biomass per unit of nutrient |
low nutrients
low tissue turnover, high NUE, long persistence dry, infertile, shaded stress tolerators |
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high nutrients
high resource capture, rapid growth, rapid tissue turnover, low NUE fierce competitors |
Human inpacts
C cycle, carbon dioxide released into atmosphere N cycle, artificial fixation, fertilizers land use, fire, clearance, industry C linked with N |
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Primary productivity-organic compounds from inorganic carbon (autotrophs)
2 types, photoautotrophs and chemoautotrophs |
Photoautotrophs-photosynthesis
solar radiation-use mostly visible sepctrum, transmit green light so appear green greater light intensity, great photosynthesis rate up to overheating point intensity unpredictable (season, clouds) leaf structure/shape changes, grow to suit light intensity |
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water
loose soils, easy to absorb. roots non-branched dense soils, vice versa water lost through leaves (stomata) in dry areas, plants are tolerators (slow) or avoiders (non until water present) |
minerals-required by plants
N, P, S, K trace Ca, Mg, Fe and others carbon-taken in through stomata variable conc (over time, daily, seasonally, spatially) |
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Chemosynthesis-organic matter created by oxidation of inorganic molecules
1.energy source (electron donor)-nitrites, ammonium, ferrous ion 2.oxygen source-water/O 3.inorganic carbon |
Light reaction-light energy converted, stored as chemical energy (ATP, NADH)
occurs in chloroplasts ATP/NADH-formed outside thylakoid, provide energy/electron to make sugar |
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Dark reactions-calvin cycle
3 carbon sugar from 3 carbon dioxide 3 phases-carbon fixation, reduction (ATP/NADH), regeneration produces 3x 5C sugar (RuBP) requires 9 ATP/6 NADH most plants use only Calvin cycle (C3) |
dark reaction-photosynthesis
high carbon dioxide, moderate conditions very water wasteful problem-photorespiration (no new carbon fixed, O produced, energy wasted) bad in dry climates |
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C4-light/dark reactions separate
carbon intake separte from calvin cycle, stromata can close more often betetr for hot/dry environments, more energy |
Chemosynthesis-all dark reactions
hydrogen sulphide starting material ATP/NADH, same formation as in photosynthesis, electrons and hydrogen sulphur is end product |
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Primary productivity-essential for all life
plants are producers, eaten by herbivores gross primary productivity (GPP)-amount of light energy stored as chemical net primary producitvity (NPP)-amount of energy available to next trophic level. NPP=GPP-R |
Hererotrophs-feeds on others
requires, water, minerals, oxygen, organic carbon |
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Herbivores-eats tissue/internal fluids of living plants/algae
very divers, many different plants so many different animals |
frugivores-fruit eater
very rich in sugar, not much else vast quantities required to get nutrients terrestrial-where fruit is birds, mammals, rare amphibians/fish insects/fungi |
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folivores-leaf eater
carbohydrate rich, with fibre, protein and minerals very complex, difficult digestion extremely common rare in birds (heavy digestive system, limits flight) |
Nectarivores-nectar drinker
very sugar rich, high fluid, some protein Mucivores-sap drinker xylem (water), high fluid content, little energy phloem (sugars), sugar rich, little minerals |
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Granivores-seed eater
carbohydrate rich (starch), protein/fat rich hard/well defended very common insect, mammals, birds |
Palynivores-pollen eater
protein rich, carbohydrates, some fats tough exine coat usually invertebrates |
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Xylivores-wood eater
very desne, cellulose, lignin etc very difficult to digest usually fungi, smaller animals |
Algivores-algae eater
richer in protein and minerals than terrestrial plants, plus less cellulose mostly aquatic |
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Herbivore efficency
often inefficent, plants have indigestable cellulose requires-long digestive tract, grinding process, selective of material, gut bacteria, coprophagy (faeces eating) |
Plant material-low on protein, high on carbohydrate
rid off carbon, high metabolism excess water, high excretion rate |
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Access to materials
plants defend leaves, fruits, seeds often seasonal and plentiful differs in latitudinal regions hard to reach, sap, seeds |
Overcoming defences
physical, chemical strategies-behavioural, physiological Geophagy-supplement diet with external minerals |
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Heterotophs-predation
consume living organisms to survive and grow 4 broad concepts grazers, true predators, parasites, parasitoids |
grazers-remove and consume only part of prey, not certain death. many prey over lifetime
usually herbivores, not entirely |
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True predators-consume prey in entirety, prey is killed. many prey over lifetime
usually carnivores-sharp, tearing mouthparts some plants |
Parasites-eat only part of another organisms, rarely death. one/few organisms in lifetime
plant on plant, animal on plant, animal on animal common in microorganisms, fungi |
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Parasitoids-intimately associated with prey (parasties), eats parts of prey without immediate death (grazer) but death inevitable (predators)
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Eating the dead
coprophages-eat faeces of other animals usually of herbivores flies, fungi, bacteria very important for recycling |
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Saprophages-eat non-living material, can be selective
true decomposers |
Decomposers-sall scale breakdown of organic matter in organic nutrients
happens extracellulary, secrete digestive enzymes simple matter than absorbed |
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Detritivores-animals ingest macroscopic particles
usually very small eat leaf litter etc hard crushing mouthparts |
Scavengers-feed on recently dead organisms
similar to true predators, mouth parts etc can detect carrion from great distances |
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Efficiency
assimilation-% ingested material usable by organism production-% of assimilation energy incorporated into biomass consumption-% total productivity consumed by next trophic level |
heterotroph defences
physical-horns, spines etc. camoflague, mimicry. being large, fast chemical-poison, produced by heterotroph, accompanied by warning, sprays behavioural- hiding, mobbing, running, alarms/distraction |
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Overcoming defences
be bigger, faster, stronger, greater numbers resistance, sequesting (chemical) tool use |
Foraging-general vs specialist
animals are opportunists general-all food types specialist-few food types, specific prey species finding food requires: finding it (time), catching, subduing |
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Optimal foraging-to eat or not to eat
value of food item, ignore poor quality unless food items are low |
Physiology ecology-how animals function in and respond to their physical environment, at all life stages
find optimum environment, range eurytopic-wide range stenotopic-small range |
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Dealing with environment
avoid-behavioural/developmental to avoid change tolerate- confrom, regulate |
Tolerate
acclimatization-reversible changes, maintain function of organism under changing conditions (short term) adaptation-natural selection adjusts traits to improve fitness (long) stress-environmental change forces organisms tolerance |
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water balance-essential, universal solvent
60-90% of animal body mass balance between water and solutes (osmotic potential) iso-osmotic-conc of water/solute same as environment hypo-osmotic-more water outside hyper-osmotic-more water inside HWC to LWC |
Maintain water balance-ocean (more water inside)
less permeable skin drink seawater pump out solutes, urine, salt glands |
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Estuary/tidal
impermeable coating storing water burrow/hide (behaviourable) |
Freshwater (more water outside)
impermeable skin no drinking solute from food, active uptake urine, very hypotonic |
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Terrestrial
damp/humid environment nocturnal decrease skin permeability take in water (drinking, food, dew, osmotic) metabolism produces water water vapour |
Thermoregulation-thermal exchange
transferred by: conduction (direct molecule contact), depends on temp gradient, contact area, conductive properties |
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Convection-mass movement of intervening fluid
natural or forced depends on: temp gradient, dimensions, fluid properties |
Radiation-heat transfer without direct contact
depends on: object temp (higher temp, greatly increased radiation) |
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Evaporation-dissipation of heat due to high energy cost of water change of state
depends on: object temp, water vapour density not available to aquatic animals, limited water |
Thermal strategies
2 types, endo and ectotherms endotherm-energy exchange with environment ectotherm-internal metabolic processes consatnt body temp must be a balance |
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Keeping warm
activity-metabolis raised. shivering- involuntary muscle movement, high energy, little movement thermogenesis-fat burned, produces heat insulation subcutaneous fat behavioural-posture, microclimate, huddling |
Keeping cool
find shade, underground increase heat exchange (surface area) increase evaporation (sweating, panting) behavioural (dormancy, migration) |
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Ethology-study of animal behaviour
Proximate causes: what causes animal to do something (mechanisms?), behaviour development Ultimate causes: function of behaviour why its adaptive, how did behaviour evolve |
Perceiving environment-receiving info about internal condition/external environment
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Chemoreception-receptor detects/identifies chemical substances (inter/exteroceptors)
taste and smell |
Thermoreception
hot/cold temperatures external-environmental changes internal-animals thermostat |
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Electromagnetic
electromagnetic radiation sight, visible spectrum varies between species infrared, UV, even magnetic fields |
Electroreception
electrical impulses only possible in water, weak signals conducted |
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Mechanoreception
changes in pressure, position or acceleration balance, touch, hearing Lateral line system-disturbance of water pressure, used to detect prey etc |
Orientation
Kinesis-animals response proportional to stimulus intensity, non directional Taxis-movement directly towards/away from stimulus (+ve or -ve) |
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Navigation-moves from one place to another, goal orientated manner
Pilotage-using familiar landmars Compass orientation-particular compass direction True-towards a goal using some form of map |
Communication-'actors' use specially designed signals/displays to modify behaviour of 'reactors'
several methods: chemical, visual, acoustic, electrical, tactile can communicate: environmental info, sexual, parental care, social |
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intraspecific interactions- group living (solitary, gregarious, transient)
predation-large number, greater number mean great vigilance, dilution effect, confusion effect, group defence |
feeding- greater numbers, find food quicker, greater chance catching prey
reproduction-big groups, easier to find. cooperative breeding |
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Life cycles-all organisms have a cycle
either haploid or diploid Animals: direct development-born/hatches as juvenile. grows before reproduction Indirect-egg to larvae/metamorphosis to adult (two distinct stages, dramatic transformation) |
Reproduction
asexual-binary fission (copy and split), vegetation propagation, budding, fragmentation, parthenogenesis |
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Sexual-gametes, haploid cells fuse into individual
anisogamy-M/F decided by gamete size semelparous-reproduce once and die semelparity-overlapping generations iteroparous-reproduce multiple times (can be seaosnal/random) |
Life history theory-pattern of lifetime growth, development, reproduction and survival
r species: short life, rapid maturation, explosive reproduction (unstable environments, new areas) K species: long life, delayed maturation, slow reproduction (resource competition, stable environments) |
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Resource allocation
activities require resources, not unlimited allocation to one trait, cannot allocate to another trait animals must choose |
How many offspring
fitness measured by number of offspring that survive to reproduce clutch size, tradeoff between fecundity and survival optimum size should be intermediate number |
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Hierarchy of ecology
1.environment 2.organism 3.population 4.community 5.ecosystem |
Population-group of individuals of same species, particular area at the same time, interact with each other
Individual-single organism capable of independent existence modular organism: genet (genetic), ramet (physiological) individuals |
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Group
population size-how many individuals density-no. individuals per unit area populations are dynamic (changing) |
Distribution
determined by abiotic/biotic/historical factors no organism has global distribution abundance-how many individuals in given area |
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Dispersal-movement of organisms away from each other
NOT dispersion-spatial arrangement of individuals in population plants: animal, water/air current, exploding, larval natal dispersal: leaving birth area (avoid competition, dominant individuals, inbreeding, colonize new areas) |
Dispersions-spatial arrangement of individuals in population
Clumped (aggregated): close proximity to conspecifics Regular: uniformly spaced throughout environment, usually from intraspecific interactions Random: individual in one spot as likely as any other, all areas have correct environmental requirements scale very important |
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Population growth
geometric growth: changes by fixed proportion from one discrete time period to another. reproduction events must be synchronous, on fixed schedule Nt = N0 * λt λ <1: pop decreases λ=1: stable λ >1: increases |
Exponential growth
dN/dt=rN change in pop size/change in time exponential growth rate starting pop size Nt = N0 ert r>0, increases r=0, stable r<0, decreases |
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Growth
BIDE model B-births I-immigration D-deaths E-emmigration |
Regulation
density independent factors: effect regardless of density, doesnt effect growth rate, results in decrease (floods, tsunami, volcanoes, meteors etc) |
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density dependent: population changes becuae of individual density
high density= lower birth/immigration, higher death/emmigration low density=higher birth/immigration, lower death/emmigration regulate population size (space, food, water) |
Logistic growth
low density-growth rate high, size increases quickly density increases- resources depleted, growth slows and stops (carry capacity) dN/dt=rN(K-N/K) |
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delayed density dependence-fluctuate around carry capacity, time lags
predators have longer life span reproduction no instantaneous r/time lag low-logistical growth r/time lag intermediate-damped oscillations r/time lag high-stable limit cycle |
Life tables
age-not all individuals have same survival chance/reproductive potential cohort: individuals all born in given time period two section-survival/reproductive data most accurate, however requires cohort (difficult with short/long lived, stationary/wide ranging) |
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Static life tables-data from a fixed point
must be able to estimate age, assume survival/reproduction constant |
Composite life tables-averages data over several periods
+ve: doesnt require cohort, averages give reliable survival/reproduction -ve: hides fluctuations |
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Stage based life tables-age, survival, reproduction arent linked
life stages not time periods |
Survival/mortality curves
type 1: stable survival rate, drops off 2/3rds through life (humans, large predators) type 2: linear decreasing chance of survival type 3: rapid decrease in young life, very few old organisms can vary with populations, sexes, cohorts |
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Morality-m=each corresponds to survivorship curve
type 1: low chance when young, increasing exponentially 2/3 through life type 2: stable, constant chance of death throughout life type 3: increases exponentially when young, stabilises at high point. few old organisms |
Age structure-proportion of population in each age class
population growth can be predicted from life tables/age structure |
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Population extinction-growth rate can change with environmental changes
deterministic changes: predictable changes, consistently reduce growth rate Stochastic variation: unpredictable changes (environmental or demographic). not bad for large populations Allee effects: at low populations density, small populations can decrease past point of return (hard to find mates, higher predation, harder to get food) |
Applied ecology-application of ecology concepts, theories, models, methods providing basis to address real world management, conservation issues
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Counting organisms
often difficult-small/camoflaged, wide ranging/fast moving absolute pop size: estimates actual abundance of individuals (+ve more accurate, -ve time consuming, expensive) relative pop size: should relate to actual abundance, allows comparison between individuals numbers relative to one another (+ve cheap/quick, -ve misleading) tradeoff between precision/significance |
Estimating abundance
area based counts: smaller 'sample area', estimate total pop size based on total area (works on averages, quadrats) absolute pop size for: plants/sessile, slow moving relative: mobile, cryptic animals |
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Distance methods-distance organisms are from given point, estimate pop size. calculate density
detection function can correct estimates same as area based, good for plants/sessile |
Mark recapture-mark animals, release and recapture. % marked animals recaptured, estimate pop size
good for mobile animals some assumptions: no pop change during capture period, equal catch chance for individuals, marking has no effect, marks remain during sampling |
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Uses
conservations: is pop declining, area most important to save, is conservation strategy working, cause of pop change |
Population viability analysis (PVA)-mathematical process/tool set estimate probability that population will persist within time period under current conditions
incorporates chance events (environmental/demographic) |
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PVA uses: pop size for reserve, no. of populations needed for regional persistence, identify key life stages for conservation/pest control, sustainable harvest limits, no. of individuals to release in introduction
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Sustainable harvest limits: no. individuals that can be removed without risking population
1/2K maximum sustainable yield fixed quota-same number each year fixed effort: maintain constant harvest effort, no removed changes with pop size |
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Interspecific interactions
predation, amensalism (one species destroyed, other unaffected), competition |
Competition
resources- one will limit ability to grow, reproduce or survive consumed by organisms, can be depleted can also be services environmental features: salinity, temp, pH, oxygen (physical factors) |
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Types of competition
Exploitation-one species uses a resource that would otherwise be used by another species interference-species compete directly for access to resource they both require asymmetric competition (one species more harmed in competition than the other) |
Competitive exclusion principle
if two species use same limiting resource, cannot exist indefinitely (extinction for one species) two species in same stable environment, resource not used in same way greater difference, easier to coexist |
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Resource partitioning-species divide up resource so each species limited by different factor
can feed in different areas/ways, diverge in morphology/behaviour |
Modelling competition
equation involving 2 species is derived from logistic equation 4 possible outcomes: (k is limited resource) 1. species 1 higher k, more competitive 2. species 2 higher K, more competitive 3. high interspecific, low intraspecific 4.low interspecific, high intraspecific |
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Commensalism-two species where on benefits and one does not benefit but isnt harmed
problems: there may be hidden effect, absence of evidence isnt evidence of absence lack of effect ay depend on density |
Mutualism-two species where both species gain benefit from being together. not selfless or without cost, simple NET gain
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obligate mutualism-species specific, neither can survive without the other
facultative-not species specific, can survive alone symbiosis-two species live in close/direct physical contact ephemeral-loosely associated |
Characteristics of mutualism
trophic benefits: +ve interaction, one species receives energy/nutrients from another (Mycorrhiza) defence: +ve, one species provides protection/shelter service: +ve, one species provides service |
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Mullerian mimicry-poisonous species has unpoisonous copy
species dont directly interact, by product of direct benefit. common use of beneficial strategy |
Issues with Mutualism
assumptions about interactions species cheating-simply taking without reciprocating mutualism can result in runaway population growth of both species up to point. too far, one species will drop off |
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Ecological community-collection of organisms found inhabiting defined area
number of species present, diversity measure, relative abundance |
Niches-summary of organisms tolerances and requirements
each habitat, many niches describes how, not just where an organism lives |
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organism tolerances
temp, relative humidity, pH, wind speed, water flow, day light, recipitation real niche of species must be mulitdimensional n-dimensional hypervolume all factors are considered to provide a niche |
fundamental niche-overall potential niche of a species, allowing viable population (no competitors)
realised niche-more limited spectrum of conditions/resources allowing species to persist realised (narrower) within fundamental, interspecific competition |
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Competition occurs between similar species in similar niches
coexistence of species requires interspecific competition to be less than intraspecific |
niche differentation
requires: resource partitioning-utilize different resources within same habitat separate in space, time, morphology or ability |
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Niche construction-organism through activities/choices modifies own/others niche
tends to increase fitness, good for natural selection consequences: broader effects on other species/ecosystem, likely to effect own natural selection pressures |
community-assemblage of species populations occur together at same time
usually defined by physical/biological characteristics members classified by: taxonomic affinity, guild (group of species use same resource), functional groups (function in similar ways, dont use same resources) trophic webs |
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community structure- set of characteristics shape a community
species richness: no species in community, measured with species accumulation curve species evenness: relative abundance (commonness and rarity) species diversity: combines richness and evenness, shannon diversity index |
Biodiversity-25 hot spots around earth
incorporates richness and diversity, can be measured from genes to communities biogeography-study of species composition/variation across geographic locations species area curves |
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Island biogeography
1. no species dependent on balance between immigration/extinction 2.balance is dynamic 3.vary with island size/isolation richness depends on island: degree isolation, time, size, habitat suitability, ocean currents, human activity |
Disharmony-relative proportions of different taxa not same as on mainland
assmebly rules-patterns in developing/establishing communities only certain combinations of species are possible, these resist invaders stable combinations may be unstable in other locations |
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Trophic levels-position organism occupies in food web. Based on feeding relationships
Food chain: chains of animals linked together by food, all dependent upon plants energy flows up |
1.primary producers (autotrophs)
generate chemical energy from sunlight (inorganic chemical compounds) plants, algae etc usually photosynthesis detritivores: consume dead organic material |
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Primary porducers (heterotrophs)
detritivores: consume dead organic material releases nutrients, supply would be quickly exhausted without them |
2.Primary consumers- herbivores
consume primary producers (autotrophs) to obtain energy both invertebrates and vertebrates |
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3. Secondary consumers (primary carnivores)
consume primary consumers smaller predators |
4.tertiary consumers- secondary carnivores
consume secondary carnivores larger predators, usually vertebrates some omnivores have feeding links across multiple trophic levels |
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Energy flow
created at bottom level by autotrophs, flows up some lost at each level, biomass and entropy net energy decrease, final consumers dies becomes detritus only small fraction of sunlight fixed by autotrophs trophic efficency-energy passed onto next level, depends on consumption, assimilation, production |
Consumption efficiency (CE): proportion of available energy digested
assimilation (AE): proportion ingested food assimilated via digestion production (PE): proportion assimilated food goes towards producing new biomass TE=CExAExPE |
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Food webs-feeding relationship amoung organisms in all/part of community/ecosystem
Nodes: single species Links: between nodes, show predator/prey relationship (undirected vs directed) trophic position: nodes distinguished as basal, intermediate or top predators |
Types:
source webs- species arising from single food source sink webs- linked by one top predator community web- entire set of feeding relationships |
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Indirect effects- influence of one species (donor) transmitted through second species (transmitter) to third species (receiver)
complex communities interaction strength- measure of the effect of one species population size on another species population size interactions can be: direct/indirect, +ve, -ve or null |
Indirect
apparent competition-multiple non competing prey species elevates predator abundance/increased predation pressure trophic cascade-effects at one trophic level can effect species abundance at another keystone species-species tightly connected within food web |
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Complexity-does it lead to stability (less fluctuation in species population abundances)
fragile community: sensitive to pertubations artificial communities human activities |
Dynamic communites-always changing
changes: niche differentiation, species dispersal/competition, trophic structures/pathways, temporal, spatial agents: subtle, catastrophic, abiotic vs biotic, natural vs human succession-process of change in species composition as result of agents of change |
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Abiotic change
disturbance-physically injures/kills individuals, creates change for others to grow/reproduce stress- reduces growth/reproduction of individuals, creates opportunity for others Biotic changedisturbance (same as for abiotic) |
Succession
involves colonisation/extinction of community species due to agents of change stages: pioneer-after disturbance climax-equilibrium state, little change |
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Primary succession-colonisation of habitats devoid of life
can be slow, first arrivals face inhospitable habitats basic resources pioneers must withstand physiological stress to transform habitat |
Secondary succession
reestablishment of community which most organisms have been destroyed after agents of change surviving species very important |
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Facilitation model
only pioneer species can be established, make site more suitable dominant species replace/reduce pioneer abundance (competition) |
Tolerance model
any species can establish, has no effect on subsequent recruitment dominant species will still take over |
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Inhibition model
any species can establish, modifies environment inhibits growth of later species as long as early species persist, excludes/suppresses others |
Factors influencing succession:
site conditions, events after succession, species interaction, colonist availability, seeds, weather early species-fast growing, well dispersed later- competitors, stress tolerant |
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Functional groups: set of species with similar functional characteristics related to one ecosystem service
similar community assemblages reoccur through convergent evolution defined using food type, feeding habit, structure, nitrogen fixers etc |
macro/micro evolution
macro: geological time scale, above species level, compounded effects of microevolution micro: human timescale, within species |
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twin filter model
unifying filter-trait convergence diversifying filter-trait divergence eco-evolution: response to disturbance events, variation in productivity, environmental change fluctuation in community structure |
Community genetics-evolutionary genetic processes occur among interacting populations
in communities |
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Community ecology-study of patterns in structure/behaviour of multispecies assemblages
ecosystem ecology-concerned with structure and behaviour of systems focus on energy and matter flux |
Changing climate
Milankovich wobbles-earth axis tilt, climate fluctuations (ice ages) plate tectonics-land mass moves, climate changes can change landscape, mountains, rainfall etc Mountains-increased physical/chemical weathering, increased CO2 usage |
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Mass extinction- Pulse-rapid press-slow (geologically) 3 main time period extinctions Late Ordovician earth had large CO2 conc, earth warmed ice melted, organisms adapted to cold died |
Ocean circulation-difference between poles/tropics, continent positions cold water sinks, engine of circulation evaporation increases salinity colder earth, larger circulation consequences: oxygenation, nutrients, carbon removal, |
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Ordovician cause: 1-mountains thrown up, chemical weathering, CO2 removed, cooling begins 2-cooling increases ocean circulation, increase in nutrient/oxygen cycle, marine productivity increases, CO2 removed, earth cools mass ice sheets, glacial weathering. no chemical weathering, earth slowly warms |
Ordivician final: earth warming, ice sheets retreat rapidly cold adapted organisms die |
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Extinction 2: Permian land joined as pangea, very dry lots CO2, temp rose slow warming, methane hydrate unstable, mass free methane (rapid warming) warm sea, no circulation so no oxygen/nutrients anaerobic marine organisms, warmer still over 80% of all organisms however important, increased diversity in future |
3rd extinction- K/T boundary (dinosaurs) asteroids impact in mexico (65 mya) emitted substances-CO2, SO2, dust dust clods etc produce volcanic winter, solaar radiation reflected other factors-volcanic activity india, rising sea levels |
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Aliens-invasive, competition for native species asymmetric competition-one species harmed more than other amensal-one harms another human introduction, geographical land change |
Invasion stages-from native habitat 1-captivation/cultivation 2-survival in wild 3-naturalised 4-spreading 5-pest! 1 in 10 rule escape-establish-expand |
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Pests
location-certain environments better suited to invasion remote islands-good (hawaii) continental, high biodiversity-bad (china) Land/sea-marine, not easy to invade Habitat. aggression, fecundity |
Habitat alteration 1-add species (facultative mutualism), super gneralist 2-remove species (total,local or frequency extinction) 3-habitat alteration (plantation, grazers), monoculture 4-Pollutants (pesticides/fertilizers, industrial, CO2) 5-change climate (temp change, organisms move to ideal temp) 6-fragment habitat (reduced gene flow, however can increase biodiversity) |
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sustainability-protecting ourselves/own species Conservation-protecting other species many different levels (genes, species, ecosystem) changing habitat, creates conservation problems tools: best to leave alone |
Conservation protection ex situ (zoos), direct help (intervene at key life cycle points), remove/add species fragment habitats, protect specific genetic alleles habitat alteration-preserving natural biocontrol- specialists conservation requires understanding! |
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Our time period-Anthropocene constant evidence of human activity waste (oceans, plastics etc) forest cover, agriculture land animal biomass (domesticated, farming) nitrogen flux |
Total animal species-only estimate: 1-comparison well studied groups 2-extrapolate using body size 3-estimate diversity of most numerous groups ratio of tropical/temperate 1:2 no. species increases exponentially as size decreases |
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Modern extinction rates-background natural extinction around 2 species per year current rate around 350x greater, 700 per year coral bleaching, deforestation habitat repair etc required accelerated evolution-hybrids, introgression (gene flow between species) |
Sustainability-planet cannot cope with current human growth rate overpopulation effects: climate change, ecological degradation, starvation accepting climate change? profit, fear, ideology |
