Ecological niches

• Ecological niche


  Role of an organism in an ecosystem
• Ecological niche

  • Zones of tolerance for abiotic variables determines habitat
  • Food supply is biotic -> can be heterotrophic or autotrophic
  • E.g. nesting sites in trees of pollination of flowers
• Obligate aerobe


  Needs oxygen (animal + plant cells)
• Obligate anaerobe


  Oxygen must be absent (tetanus bacterium)
• Facultative anaerobe


  Grows better with oxygen but can survive without it (yeast)
• Photosynthesis


  Production of organic compounds in cells using light energy
• Organisms that can photosynthesize

  • Plants
  • Algae
  • Photosynthetic prokaryotes
• Autotroph


  Synthesize organic compounds using other sources of energy
• Types of autotrophs


  • Photoautotrophic: photosynthesis (plant, algae, protist)
  • Chemoautotroph: chemosynthesis (archaea, bacteria)
• Heterotroph


  Consuming other organisms internally or externally
• Types of heterotrophs


  • Saprotroph: secrete enzymes, external digestion of dead or decaying matter (fungi, bacteria)
  • Parasite: obtain food from other organism without killing it
  • Holozoic: complex food particles taken in and broken down
• Holozoic heterotrophs


  • Herbivore: goats, rabbits, cows
  • Carnivore: lion, tiger
  • Omnivore: bear, human
• Holozoic nutrition


  1. Ingestion

  2. Digestion

  3. Absorption

  4. Assimilation

  5. Egestion
• Mixotroph


  Uses both autotrophic and heterotrophic modes of nutrient uptake
• Obligate mixotroph


  Requires both autotrophic and heterotrophic modes of nutrition to survive
• Diversity of nutrition in archaea

  • Phototrophic uses light energy
  • Chemotrophic uses organic chemicals such as iron by oxidizing Fe2+ to Fe3 to produce sugars
  • Heterotrophic, oxidizing organic compounds obtained from other organisms and digesting them
• Family Hominidae


  • Hominids
  • Includes Homo sapiens and recent ancestors
  • Homo florensiensis and Paranthropus robustus
• Hominids


  • Herbivores: eat plants, large flat teeth and strong jaw for grinding seeds, flat molars
  • Omnivores: sharp incisors for ripping meat and very flat molars
• Plant defenses against herbivory

  • Physical structures: thorns on blackberry bushes
  • Sharp trichomes on stinging nettles contain irritating chemicals
  • Grass has tough fibrous leaves
  • Chili plants contain capsaicin
  • Tobacco contains nicotine, tobacco horn worm moth evolved to detoxify nicotine
• Adaptations of herbivores


  • Grazing mammals have flat molars for grinding, teeth grow throughout life
  • Insects have strong muscles and sharp mandibles with serrated edges to cut through cell wall
  • Piercing mouthparts, aphids have stylets to reach phloem and obtain nutrients
• Adaptations of predators and prey

  • Structure: vampire bats have pointy upper front teeth, sharp claws and strong jaws and teeth
  • Chemical: black mamba venom paralyses and kills
  • Behavioral: anglerfish wave luminescent fin rays to lure prey, wolves hunt in packs
• Plant adaptations for harvesting light

  • Trees reach the canopy with tall trunks, broad crowns and leaves
  • Lianas climb, grow rapidly, have flexible and thin stems and large broad leaves
  • Epiphytes on branches, broad leaves and flexible growth
  • Strangle epiphytes germinate in canopy tree branches, send aerial roots down
  • Shade tolerant plants branch to increase surface area
• Fundamental niche


  Niche that an organisms could potentially occupy in the absence of competition from other species
• Realized niche


  Niche an organism occupies due to competition from other species
• Competitive exclusion


  No two species can occupy the same niche
• One species will be better adapted and outcompete and exclude the other</b>
• The less adapted species is eliminated from the niche or restricted to part of it
• Species occupying realized niche

  • Grey and red squirrel