Topic 2: Ecology (2.1 Ecosystems; 2.2 Energy FLOWS/Biomass; 2.3 Biogeochemical cycles; 2.4 Climate + Biomes; 2.5 Zonation, succession, ecosystem transformation)

Taxonomy

• Taxonomy used describe/classify organisms:

  • Domain

  • Kingdom

  • Phyllum

  • Class

  • Order

  • Genus

  • Species

Ecosystems

• Ecosystem = made all living + non-living things within environment

Species

• species = group organisms share CHARACTERISTICS + can breed, FERTILE offspring (not mule!!)

  • “KEYSTONE species”; species w/ critical role maintaining ecosystem (ex. Otters eat urchins, protect kelp!!)

Population

• Population = group ONE single species living SAME AREA, interbreed

  • (*one species living in TWO ponds NOT population; two separate populations)

  • population DENSITY —> average # individuals per given area; based birth/death rates, migration, etc.

LIMITING FACTORS

• LIMITING FACTORS slow population growth; carrying capacity

  • biotic; lack food, predation, no mates, inter/intra-species competition

  • abiotic; lack water, oxygen, low light, freezing temperatures, natural disasters

  • density-dependent (as population ⬆); predation, intra-species competition, disease, waste

  • density-independent; natural disasters, human affects

cause population fluctations

• LIMITING FACTORS cause population fluctuation —> cyclical oscillations

• MODELS;

  • j-curves; exponential growth, no LIMITING FACTORS = sudden “dieback”

  • s-curves; standard—exponential growth into LIMITING FACTORS to carrying capacity

  • ==> ‘idealized’ j + s-curve is what populations usually look like;

    • **NOTE: CARRYING CAPACITY is pop STABILIZES. NOT always highest point.

Human carrying capacity? — ISSUES Measuring

a) too many resources used

• *imported resources — outside direct niche

b) varying lifestyles too much

c) technology goofs

Niche

• set all biotic + abiotic factors where species LIVES

  • milk, honey, etc. are BIOTIC — *products count as biotic

• Fundamental niche vs. REALIZED niche

  • FUNDAMENTAL niche is ALL possible conditions species could survive/reproduce

  • REALIZED niche is where ACTUALLY survives/reproduce (bc predation, limited resources + competition)

**NOTE: [environmental] niche vs. ECOLOGICAL niche (specie’s role in ecosystem)—NO two species can inhabit same role (@ same time/place)

community

• community; group two or more species living same area—communities share habitats!

Inter + Intra-species competition

• Interspecies comp

  • based territorial (resources), mates

• Intraspecies comp

  • resources—either share OR one DOMINATES

    • “competitive exclusion”; dominant species coexist w/o wiping lesser species

RELATIONSHIPS (between species)

1. Predation

2. Carnivore

3. Herbivore

4. Parisitism — lives off host; ex. leech, fleas, etc.

5. Mutualism —BOTH benefit; ex. clownfish and sea anemone

6. Saprotrophism — saprotroph feeds dead organics, recycling nutrients

• ↳ scavengers (vultures) eat decaying flesh

• ↳ + detritivores (fungi, bacteria); no “eat”, secrete enzymes break down

Disease

• higher population density ⬆ disease spread

• (+ warmer, humid climates)

• pathogens, bacteria, viruses, fungi

First Law of Thermodynamics

• First Law of Thermodynamics = energy CAN’T be CREATED or DESTROYED.

  • (thus, energy just flows around the system!)

1) Photosynthesis

• ~plants; carbon dioxide + water → glucose + oxygen (cellular respiration)

• sunlight used split water to combine to glucose

2) Cellular respiration

• EVERYTHING (animals, plants, etc.) cellular respiration!!

  • Cellular respiration = food/glucose broken down to ENERGY.

*note—heat generated bc respiration loses energy (entropy, energy unavailable do work)

• aerobic (w/ oxygen) + anaerobic (w/o oxygen) respiration

heterotrophs, autotrophs, etc.

• side note: heterotrophs (consumers—animals) vs. autotrophs (make own food—plants), photoautotrophs (photosynthenetic bacteria), chemoautotrophs (bacteria near deep sea vents w/o sun)

Second Law of Thermodynamics

• Second Law of Thermodynamics = entropy ALWAYS increases (or constant)

  • bc energy transferred/transformed→ degrades to less useful/efficient form (i.e. heat), ⬆ entropy

food chain

• food chain points flow energy one organism → next; single hierarchy

  • producers (autotrophs) make own food w/ photosynthesis :3

  • consumers (heterotrophs) gain food other organisms

==> Food webs made intertwined/complex food chains

trophic levels

• trophic level = within food chain, level organism

  • producers (plants) →primary consumers → secondary consumers →tertiary consumers

  • *note: only ~10% energy transferred per level—rest lost respiration/heat

• POSSIBLE reasons TROPHIC ‘loss’:

  • a) (mainly) lost respiration/heat

  • b) not all eaten (bones, etc. + die natural causes)

  • c) varies 5-20% between species bc warm-blooded use more energy

productivity

• productivity ⇒ rate ecosystems generate biomass (energy/mass per area per time)

  • gross productivity (GP) = total biomass intake by organism

  • net productivity (NP) = net biomass intake - respiration

Max sustainable yield (MSY)

• Max sustainable yield (MSY) is net productivity species/trophic lvl harvested w/o reducing future supply

Ecological pyramids (+instead food webs/chains)

• Ecological pyramids model qualitiative (biomass, productivity, etc.) differences between trophic levels

• PROS:

  • document energy transfer/loss

  • shows what eats what

  • reflect ecosystem balance?

—TYPES—

• 'A. number pyramids’ — # organisms per level

  • easy overview

  • BUT disregards size/juvenile + LOTS counting

• biomass pyramids’ — biomass per level

  • considers size per indiv

  • BUT must kill to measure, only sample masses anyways

• ‘energy pyramids’ — productivity/energy per level

  • over time, diff. ecosystems, second law of thermo

  • BUT must measure growth over time, where detritivores ?

bioaccumulation

• as result chain/web/pyramid, biocides (ex. pesticides) “bioaccumulate” in ecosystem—"biomagnification” upwards chain (bc consumer eats LOT grass, even if small amount per grass)

Biogeochemical cycles

• biogeochemical cycles (hydrological, carbon, etc) cycles keep the world running!!

  • involve:

    • 1) stores (storages) = organic + inorganic equilibrium w/ environment ;steady-state equilibrium

    • 2) sinks = net accumulates

    • 3) sources = net released

THE CARBON CYCLE — (biogeochemical cycle!)

• carbon CYCLING:

  • per definition, carbon cycles through living + non-living things

    • a) carbon fixation = living organisms sequester carbon naturally bc absorb carbon dioxide + convert to biomass

• FAST vs. S L O W carbon cycles…

  • FAST— biotic, one animal/lifetime → land/atmosphere/ocean

  • S L O W—abiotic, millions years; soil→rocks →ocean

==> [sinks? stores? source?] WHERE “DYNAMIC” CARBON CYCLE?!??

• carbon STORES (inflow/outflow/steady-state equilib.):

  • LIVING — living things (humans, animals, plants, etc.)

  • NON-LIVING — atmosphere, rocks/soil, oceans (and shells!!)

• Agriculture

  • sinks: ‘regenerative’ methods—crop rotation, polyculture, cover crops, etc.

  • source: excessive tilling, monoculture

  • stores: long-time croppage = store (ig equal-ish cycling)

• Forests

  • sinks: gud forest! = sink (carbon sequestration w/ photosynthesis)

  • source: forest fires, decomposition

  • stores: also forest bc photosynthesis (inhale) —> some respiration (exhale)

• Oceans

  • sinks: sequester ~25% atmospheric carbon…BUT ocean acidification