Last Bio Unit 🍊: 4/day

• Interactions within Ecosystems

  Ecology: Interactions bw organisms (biotic) & environment (abiotic)

  • Ecotones: Transition areas bw ecosystems w/higher biodiversity = more stable food webs.
  • Ecological Niche: Organism’s role in an ecosystem including its place in the food web, habitat & breeding area

  > No 2 species have the same niche

  > Introduction of exotic species = competition (ecosystem disruption)

  • Biotic Potential: Max offspring produced w/unlimited resources determined by:

  > # of offspring per birth

  > Breeding frequency

  > Reproductive Life time

  > Survival until reproductive age
• Limiting Factors/Environmental Resistance


  Environmental conditions preventing population from biotic potential.

  Abiotic Factors:

  • Light (too much/little)
  • Temp (too cold/warm)
  • Harmful chemicals
  • Bioaccumulation
  • Matter cycles

  Biotic Factors:

  • Excessive predators
  • Predator/prey dynamics
  • Hunting
  • Invasive species
  • Diseases/parasites
  • Insufficient food
  • Food chains/webs
  • Competition
  • Reproductive ability
  • Symbiotic relationships
• Carrying Capacity

  Max # of individuals a species can support in an ecosystem at a given time dictated by factors:

  • Exceeding Capacity: Population decline until re-stabilized

  Abiotic Factors:

  • Law of Minimum: Growth limited by the scarcest source
  • Law of Tolerance: Survival possible only within a specific range of an abiotic factor

  Biotic Factors:

  • Density Dependant: Affect large pops due to density (disease, food, resource competition)
  • Density Independent: Affect pop regardless of size (natural disaster, climate change)
• Sustaining Ecosystems

  Naturally change over time but human impact often disrupt balance & replenishment of resources.

  • Terrestrial & aquatic ecosystems face distinct limiting factors & challenges to sustainability
• Terrestrial


  Abiotic Limiting Factors:

  • Soil: Give nutrients, but ☹️quality is limiting

  > Litter: Partly decomposed leaves & grasses

  > Topsoil: Small rocks & decaying matter

  > Subsoil: More rock w/ organic matter

  > pH: Acid deposition, leaching & percolation; diff plants like diff pH

  • Water:

  > Surface: Rain above ground

  > Ground: In soil & porous rock; water table level varies w/rain

  > Plant Adaptation: Roots reach groundwater/water table

  • Temp

  > Adaptation: Hibernate, shed leaves, winter coat, dormancy

  • Sunlight

  > Affect ecosystem; varies by geographical location & plant canopy
• Grassland Biomes (Prairie’s)


  Large rolling terrain w/grasses, flowers, herbs, bushes.

  • Few large trees bc of thin soil, windy condition & inconsistent moisture (erratic, isolated rain)
  • 2 seasons: Growing & dormant so there’s high animal migration: coyote, deer, elk, geese, rodent, birds of prey
• Deciduous Forest Biome 


  Leafy trees

  • Soil: Thick, nutrient-rich bc of moisture & decomp
  • Plant adaptations: canopy & vining for sunlight, complex root systems for water & nutrients
  • Biodiversity: High bc of abundant plants providing food & habitat
  • Animal adaptation: camouflage
• Taiga Biome (‘Canadian Shield’)


  Very cold, windy, dark & desolate

  • Vegetation: Many conifers (needle-bearing) trees w/thick roots to break through rock, low water conditions (bc low temp)
  • Biodiversity: Low due to sparse plant life
• Changes to Terrestrial Ecosystems

  Forestry

  • Deforestation methods (slash & burn, clear cutting, selective cutting) impact ecosystems: degree of impact depends on method.

  Forest fires: Bad thing is displaces animals & ppl and disrupts carbon cycle

  • Natural ecological process, often promotes renewal & rebirth
  • Clean up dead plant material, stimulate regrowth of healthy plants
  • Quick recycling/decomp of waste & nutrients
• Water Quality

  Determined by factors:

  • Bacteria: Higher disease risk (coliform from human waste)
  • Dissolved Oxygen (DO): Essential for aquatic life (less DO = less aquatic life); affected by decomposing bacteria & thermal pollution
  • Biological Oxygen Demand (BOD): Amount of DO needed by decomposers to break down organic matter in the water over 5 days
• Population Growth Curves

  J-Shaped Curve: Boom & bust growth pattern

  S-Shaped (Stationary) Curve: Steady growth, typical of open populations

  Lag Phase: Slow birth rate due to adjustment period

  Growth Phase: Exponential growth w/high birth rate

  Stationary Phase: Birth rate = death rate

  Death Phase: High death rate

  A) J-Shaped Curve

  B) S-Shaped Curve

  C) Lag

  D) Growth

  E) Stationary

  F) Death

  
• Aquatic Ecosystems


  Vital to Earth’s ecology; often diverse

  Abiotic factors:

  • Chemical environment (dissolved O2)
  • Light levels!!! (why diff lake zones exist!!!)
  • Temp

  Oligotrophic Lakes:

  • New, deep, cold lakes
  • ⬆️ O2 content (support larger fish); ⬇️ nutrient levels

  Eutrophic Lakes:

  • Older, shallow, warm lakes filled w/detritus. Eventually become marshes > dry land.
  • ⬇️ O2 content (less fish); ⬆️ nutrient levels (algae blooms)

  A) Littoral Zone

  B) Limnetic Zone

  C) Euphotic Zone

  D) sunlight

  
• Taxonomy (Donald kills ppl coming out from Greater Syria)

  Hierarchical classification system w/organisms divided into smaller groups based on similar characteristics (dichotomous keys)

  • Domain:
  • Bacteria: Unicell prokaryotes (w/o nucleus)
  • Archaea: Unicell organisms like bacteria w/slight genetic differences
  • Eukarya: Eukaryotes (w/nucleus)
  • Kingdom:
  • Monera: Prokaryotic organisms (bacteria & archaea)
  • Protista: Unicell eukaryotes
  • Multicell eukaryotes: Plantae, animalia & fungi
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species: Interbreed = fertile offspring and interest
  • Subspecies
• Binomial Nomenclature


  Naming system by Carl Linnaeus written as 'Genus-species'. Independently underlined or italicized
• Phylogeny & Evolution


  Phylogeny: History of evolution of a species or group of organisms

  • Phylogenetic trees can be used to show evolutionary relationships

  Evolution:

  • Definition 1: Theory that changes occur & can be seen in inherited traits of a pop from one generation to another
  • Definition 2: All living species are descendants of ancestral species & are diff from modern day ones due to the cumulative change in the genetic composition of a pop
• EVOLUTION EVIDENCE: Paleontology 


  Study of fossils shows historical proof of organisms that once lived & reveals patterns:

  • Earth had species very different from current ones.
  • Organisms have become more complex over time systematically.
  • Living species & their fossil matches found in the same regions.

  Fossil age estimated by rock age through radioactive decay (radioactive elements lose mass & particles at a constant rate regardless of moisture, temp, pressure).

  Half life = Time for half the sample to decay & stabilize.
• EVOLUTION EVIDENCE: Biogeography


  Study of the distribution of organisms on Earth.

  • Continental Drift redistributed organisms. Continents can be aligned geographically & biologically to show past connections.
  • Isolated Islands: Have unique sets of organisms. Their evolutionary pressures & organism's past can be studied.
• EVOLUTION EVIDENCE: Anatomy


  Similarities & differences in anatomy and embryological development/structure (embryology) can show ancestral links bw organisms.

  • Homologous Structures (Divergent Evolution):
  • Similar structures w/different functions show evolutionary relationship from common ancestor (bat wing & our hand)
  • Analogous Structures (Convergent Evolution):
  • Diff structures w/similar functions show little to no evolutionary relationships (bat & butterfly wing)
  • Vestigial Features:
  • Rudimentary structures w/no clear function, possibly evolving out of existence (wisdom teeth)
• EVOLUTION EVIDENCE: Biochemical/Molecular


  Amino acid sequences in proteins are more similar in related organisms than in unrelated ones.

  DNA sequences control traits through genes; more similar organisms have more similar DNA

  Similarities also found in nitrogenous waste products, hormones & chromosomes (chimpanzee's 48 fused to human's 46)
• EVOLUTION EVIDENCE: Selective Breeding (Artificial Selection)


  Shows evolution by mimicking natural selection

  • Ex. Bacterial resistance & DNA change
  • Ex 2. Dire Wolves, Musk Ox & Silver Fox: Bred for temperament to be domesticated = new species w/ diff features
  • Ex 3. Italian Wall Lizards: Moved islands & had changes in head sizes and bite strength
• Adaptations


  Changes improving an organism’s chance of survival

  • Structural/Physical: External changes (ex. Fur)
  • Physiological: Internal changes (ex. Many stomachs)
  • Behavioural: Behavioural changes (ex. migration, hibernation)
• Variation


  Mutation: Random DNA sequence changes

  • Beneficial: Improve survival/reproduction; selected for & accumulate (ex. Bacterial resistance to antibiotics)
  • Neutral: No effect on individual
  • Harmful: Hinder survival/reproduction; selected against & disappear

  Sexual Reproduction: 2 parents w/ 2 copies of genes; 1 passed by random

  • +: High variation & best for adapting to changing environments, often removing & masking faulty genes.
  • -: Require time & energy

  Asexual Reproduction: 1 parent

  • +: No variation (can lead to unstable pop.), best for stable environment
  • -: Fast, easy & low energy
• Speciation

  Formation of a new species via allopatric speciation

  1. Physical barrier divides a pop into 2 isolated groups
  2. Diff environmental pressures cause groups to evolve independently
  3. Accumulated differences prevent interbreeding = 2 diff species

  New Age Theories of Evolution

  • Gradualism: Speciation occurs very slowly thru natural selection
  • Punctuated Equilibrium: Speciation occurs very fast in bursts, followed by long periods of stability, driven by natural selection
• Peppered Moth (need to know??)

  Typica (Light):

  • Dominant in pre-industrial England; camouflaged w/tree bark

  Carbonaria (Dark):

  • Industrial pollution darkened landscape & camouflaged against dark backgrounds
• Divergent & Convergent Evolution

  Divergent (Homologous structures; allopatric speciation)

  • Evolution into many diff species bc of diff environmental pressures
  • Darwin: “Descent w/Modification”: physical (island formation, wall, mountain) or biological (pheromones, enemies) barriers

  Convergent (Analogous):

  • Evolution of similar appearance, structure, or behaviour in unrelated species due to similar environmental pressures
• Evolutional Theories


  Lamarck: Inheritance of acquired characteristics

  • Use-disuse: Develop helpful (passed to offspring) & lose useless traits for survival
  • Believed evolution was unidirectional

  Darwin: Natural Selection (Survival of the Fittest):

  • Believed evolutional changes w/environmental conditions (natural selection & competition)

  1. Variations exist among organisms
  2. Changing environment = overpop = competition for limiting factors
  3. Better-adapted traits survive & reproduce
  4. Adaptive traits passed to offspring
  5. Natural selection always occurs & is mechanism for change.