Ecology

textbook UWD1595

Marks

• miderm 25%
• final 75%

intro

• ecology: scientific study of relationships(with world, same/diff species) between organisms and their environment(physical/biological); multidisciplinary etc
• field and/or lab experiments
• large or small scales in space and time
• natural history: study of how an area's organisms are affected by climate/soil/predators/competitors/evolutionary history via field analysis
• climate diagrams: temperature (left axis) and precipitation (right axis) over time, plus other stuff

on land

• biome: major division (via diff wildlife, climate) of land
  • tropical rain forest: (<10 latitude) soil poor as water leaches nutrients, organic stuff decomposes quickly
  • tropical dry forest: (10-25 latitude) most trees dormant in dry season (1/2 year)
  • tropical savannah: (10-20 latitude) seasonal drought, fire (with first rain), impermeable soil; few trees unlike rainforest so 2Dish, nomadic wildlife
  • desert: drought, (30 latitude; 20% of Earth's land) flash floods, heat, bitter cold; cold when wet (huh??); leaves small/angled/reflective to reduce heat; animals deal via behaviour
  • temperate woodland/shrubland: (30-40 latitude) usually hot/dry summer otherwise cool/moist, fires frequent so thick/tough barked trees and fast resprouting shrubs and some grow just during moist/wet time
  • temperate grassland: flat prarie; wetter than desert but sometimes drought; winters cold and summers hot; fires
  • temperate forest
  • boreal forest
  • tundra
  • mountains
• soil structure affected by
  • climate: rates of weathering of parent material, leaching, erosion, particle transport, decomposition, also wildlife
  • organisms: organic matter, burrowing animals' soil mixing
  • topography: rate/direction of water flow, erosion
  • parent material (part above bedrock): duh
  • time: duh
• latitude/season climate diff due to uneven heating of Earth by sun + axis tilt; biomes due to this (especially temperature/precipitation)
• three air circulation cells per hemisphere needs work here

in water

• 71% of Earth: 97% ocean, 2% ice caps/glaciers, <1% fresh; most of terrestrial life needs freshwater
• biology environments due to light/temperature/water movement/chemistry(salinity/oxygen)

temperature

• microclimate (few kms to cms; hours to mins) = macroclimate + local landscape (altitude-temperature, topographic/etc-shade, albedo-temperature)
• varies less in water since high heat capacity; much heat absorbed during evaporation, given off during freezing (high latent heat of vapourization and fusion)
• species need specific narrow temperature range
• photosynthesis CO₂+12H₂O --light energy, chlorophyll--> C₆H₁₂O₆+6O₂+6H₂O
• acclimation: short-term physiological adjustment to environment, reversible

organisms' heat balance

• heat gain: metabolism (due to cell respiration)
• heat gain/loss: conduction, convection (between fluids), electromagnetic radiation, evaporation
• poikilothermic (temp varies with environment) ectotherms (external sources of heat) = "cold blooded"
  • low metabolic rate, high thermal conductance with environmnet; most energy production from anaerobic respiration (depletes stored energy) so only short energy bursts (3-5 mins)
  • can allocate more energy to growth (although not too big as hard to exchange heat fast); can lower metabolism during harsh conditions (better extreme survival)
• homeothermic (constant temp) endotherms (internal (metabolic) heat) = "warm blooded"; some fish and insects heat critical organs
  • rely on insulation, evaporative cooling, changing metabolism
  • less energy for growth, small organisms use more metabolic activity per mass relatively
  • aquatic endothermy: high conductive/convective heat loss so few species; heavy insulation (blubber=fat), countercurrent heat exchange in dolphin fins etc
• plants: in desert minimize heat via narrow, reflective leaves that dont touch the ground and open to wind; in arctic dense (no wind) and close to ground etc
• avoid extremes via resting: inactivity or reduced metabolism:
  • torpor: short term (eg 1 day/night) eg hummingbird if scarce nectar
  • hibernation: dormant state during winter
  • estivation: dorman state during summer

water

• challenges: water loss (in desert, salt water), dilution of body fluid (in fresh water); water balance related to thermal balance (evaporative cooling)
• water moves from low to high concentration areas, rate depends on concentration diff
• terrestrial evaporation form organism depends on temperature, water content
• measure water vapour via density or pressure; relative humidity = water vapour density / saturation density; saturation density proportional to temperature
• vapour pressure deficit (vpd) = X water pressure (of air) - Y water pressure (??)
• aquatic: solutes inversely proprotional to water; increasing solutes is freshwater, ocean, saline lakes
• osmosis: water diffusion; osmotic pressure: across semi=permeable membrane due to water moving down concentration gradient; organisms are:
  • isomotic: everything equal
  • hyperosmotic: osmosis to internal
  • hypoosmotic: osmosis to external
• water potential: capacity of water to do work = its free energy content; water flows to lower energy; water (inversely?) potential proportional to solute content
  • pure water is 0 Pa, so stuff in nature is -# Pa; dry air=-100Pa; top of plant=-4Pa; soil -0.6Pa
• plants: water potential increases upwards
• qualified potential gradient mechanisms: evaporation, matric forces, solutes; hydrogen bonding in water means that evaporation from leaves pulls up more water

water regulation

• animals on land: gain (drinking, food (moisture+metabolic), absorption) - loss (evaporation, secretion/excretion)
• plants on land: gain (roots, air absorption) - loss (transpiration, secretion/reproductive structures(eg seeds))
• absorbing water from air important mostly for (??)
• metabolic water: oxidizes carbohydrates, protiens, fats via aerobic respiration (reverse of photosynthesis)
  • C₆H₁₂O₆+6O₂ --> 6CO₂+6H₂O
• plants' root:shoot biomass ratio goes up for dry places
• animals reduce loss via waterproofing (eg wax), concentrated excrement, condense+reclaim vapour in breath, inactivity (eg diapause=arrested development stage mostly in insects)

argh need to put stuff in here :-(

• energy sources: light, organic stuff, inorganic stuff

• stomata exchange CO₂ and O₂
• diffusion of CO₂ into (slower) and H₂O out of (transpiration-faster)leaves
• photosynthetic pathways related to water stress

• branches have lower nitrogen

A

1 false

2 true

3 false

4 false

B

5 d

6 c

7 d

8 a

9 b

10 b

11 ?

12 e

13 bla

14 bla

15 phenotype

16 endotherm? read slides bla

17 osmosis

18 for a home ?

19 nutrients washed away, some other thing that i forget, it's in my own notes

20 tilt on our axis, spin on axis, move along orbit

21 stuff looking like other stuff, presumably

22 more leaf-growing?

• macronutrients C O H N P = 93%+ of biomass
• herbivore problem: plants have relatively C>N, but ratio is better "farther from trunk"; dead anything is even worse
• mimicry: mullerian when animals are also noxious, but batesian when actually harmless