gistfile1.md

Intro to ecology (52)

• abiotic factors: SWATS (soil, water, air, temp, sunlight)

• organismal ecology: how a single organism interacts with its environment

• population bio: how a group of organisms interact with their environment; how and why a pop size changes over time

• community ecology: how species interact (bear eating a fish)

• ecosystem ecology: nutrient and energy flow -- maybe recyclers consuming a dead fish, and how they impact things

• sunlight -> heating -> air movement -> water movement. All because of differentials.

• Remember angle of incidence, spreading same "volume" of sunlight over larger area in higher latitudes (northern europe more sun than central africa)

  • sunlight chief limit in water (photo...trophic zone?)
  • water chief limit on land

• Coriolis forces cause deflection of movement

  • explains prevailing winds and convection cells

• biomes defined by: combination of temperature and precipitation, temp variation and precip variation

• gross primary productivity: number of C-C bonds is proportional to amount of energy fixed

  • primary producers are vascular plants on land
  • primary producers are algae in aquatic

• amount of energy fixed that doesn't go into cellular resp-- BAR (biomass accumulation)

• it's thought that more species exist in tropics because anything works there, and has just had more time

• below some precipitation amount, only highly specialized plants make it (cactus!)

• as there is more rain, forests replace grasslands (again, water limiting abiotic factor)

• visible spectrum - at 10ft down, 80% of light is gone. Remember that vision developed in aquatic environment. So must have been near surface, and spectrum ended up that which may be seen in water

  • remember that light travels a good bit further in fresh water than sea water

• water:

  • littoral zone -- where rooting may take place
  • limnetic zone -- surface, photic. Where cyanobacteria and algae are.
  • benthic zone -- below ~10ft in ocean, little light, mostly filter feeders, detritivores

• deeper lake structure:

  • surface, sees temp fluctuation, O2 mixing -- epilimnion. IN COLD WEATHER, can drop from conduction, sinking below mesolimnion. zaps thermocline (gone).
    • possible smelly from gas in anaerobic hypolimnion, once uniform
  • thin layer with sharp temp gradient -- mesolimion -- temp gradient is thermocline
  • deep, not well O2, constant very cold -- hypolimnion

• oligotrophic -- fewer nutrients

  • dissolved O2 says more-or-less consistent from top to bottom
  • dissolved O2 goes up a little in summer as depth decreases
  • LOW productivity have plenty of O2 from top to bottom

• eutropic -- lots of nutrients

  • dissolved O2 goes way down in summer as depth decreases
  • dissolved O2 varies a lot more in winter -- as depth decreases, falls off chart.
  • HIGH productivity run out of O2
  • lots of decomposition happens from fishkills -> even more nutrients for algae

• ocean:

  • intertidal zone -- plants root
  • neritic zone -- close-in. Photic top
  • oceanic zone -- further out. Photic top

• invasive species -- brown tree snakes in guam, cheatgrass here

behavior (53)

• proximate case: stimuli, learning, experience, state (hormones, hunger, injury

• ultimate causes: reproduction

• fixed vs learned action patterns

• fixed -- first time is right. Low variation, species specific, completes

  • innate

• learned

  • costly
  • habituation, imprinting, associative, advanced cognitive learning

• releaser is a signal

• release mechanism is RECEPTION of that signal

  • innate or learned

• kin selection: hamilton's rule (benefit to recipient)/(cost to altruist) = 1/(coefficient of relatedness)

  • some r values:
    • Relationship r
    • Full siblings 0.5
    • Half siblings 0.25
    • First cousins 0.125
    • Parent - offspring 0.5
    • Uncle/aunt - niece/nephew 0.25
    • Grandparent -grandchildren 0.25
    • diploid father x diploid mother = 0.5 r siblings
    • haploid father x diploid mother = 0.75 r siblings

population ecology (54)

• population density: random, clumped (social animals, env is patchy), uniform (negative interactions space them all out)

• population of populations: metapopulation

• metapopulations: some isolates (member populations) go extinct, but tend to be re-populated by neighboring isolates

• fecundity (how many offspring per female) + survivorship (how many of offspring survive)

• k-selected: low birth rate, low mortality, high survivorship, long lifespan

• r-selected: high birth rate, high mortality, low survivorship

• birth rate: intrinsic, proportional to body size

• death rate: depends on life span (intrinsic), life expectancy (extrinsic)

• intrinsic birth rate = Ntotal (maybe 2 parents + 4 kids) = Nstart (2 parents) * e^(timespan * rate)

• exponential growth happens in:

  • few individuals find new habitat
  • pop. devastated by a storm or diaster, restarts with few survivors

• density-dependent brake may act precipitously

• predator-prey relationships may oscillate, with phase lag

community ecology (55)

• interactions of individuals between different species

• niche partitioning -- speciation

• prezygotic mechanisms -- preference for one characteristic in mate

• types of competition:

  • consumptive - eat everything - tree roots
  • pre-emptive - be first -- muscle, barnacles appraoch. No more room.
  • overgrowth - overwhelm other species with numbers - literally cover, like ferns
  • chemical - make space shitty for other species (like plant move) - shrubs with no grass near them due to toxin
  • territorial - beat em up - bears!
  • encounter - opportunistic defense of random resource - hyena v vulture over a kill

• parasite vs mutualistic - cowbird and oropendola

• mutualism - ant and acacia, cleaner shrimp and fish

• keystone organism -- keep things in check

• composition of communities may be predicted based on abiotic factors (fire, disaster)

• Colonizers specialize via

  • drought tolerance
  • less nutrient needed
  • faster growing
  • r selected

• pioneer/colonizer species allows soil stabilization, which adds nutrients to soil

• after this, more complicated