Powerpoint

• Ecological Niche


  The role of a species in an ecosystem
• Ecological Niche


  • Includes the zone of tolerance for abiotic and biotic variables (which determine the habitat)
  • Mode of nutrition
  • Adaptations
  • Interactions
  • Life history
• Fundamental Niche


  The niche that an organism could potentially occupy (based on its adaptations and tolerance) in the absence of competition from other species
• Realized Niche


  The niche that an organism does occupy due to competition from other species
• Organisms compete for resources
• Competitive Exclusion


  Two species competing for the same resources leads to one species outcompeting and excluding the other species from the niche
• Competitive exclusion leads to species occupying their realized niche
• Competitive Exclusion of Barnacles

  1. Chthamalus barnacles do not live in all areas of their fundamental niche when Balanus barnacles are present

  2. Chthamalus and Balanus Barnacles coexisting

  3. The fundamental niche of Chthamalus
• Competitive Exclusion of Red Squirrels

  Grey squirrels out-compete red squirrels
• Obligate Aerobes


  Cannot survive in the absence of oxygen, carry out aerobic respiration
• Facultative Anaerobes


  Carry out anaerobic respiration or aerobic respiration depending on Oxygen availability
• Obligate Anaerobes


  Cannot survive in the presence of oxygen, carry out anaerobic respiration
• Photosynthesis


  The production of organic compounds in cells using light energy
• Organisms that use photosynthesis as their mode of nutrition

  • Plants
  • Algae
  • Photosynthetic prokaryotes
• Holozoic Nutrition


  A form of heterotrophic nutrition where an organism ingests, internally digests, and absorbs/assimilates nutrients from food
• Saprotrophic Nutrition


  Heterotrophs that obtain nutrients by external digestion of food, releasing enzymes to digest food externally and then absorbing the nutrients
• Mixotrophic Nutrition


  Can behave as an autotroph by carrying out photosynthesis, and act as a heterotroph by feeding on other organisms
• Obligate Mixotroph


  Requires both autotrophic and heterotrophic modes of nutrition
• Facultative Mixotroph


  Can switch between autotrophic and heterotrophic modes of nutrition
• Archaea are one of the three domains of life and are metabolically very diverse
• Modes of nutrition in Archaea

  • Phototrophic - using light as an energy source (not photosynthesis)
  • Chemotrophic - using inorganic chemicals to produce sugars
  • Heterotrophic - digesting other organisms
• Relationship between dentition and diet in Hominidae


  • Early human ancestors adapted to a diet primarily consisting of fibrous plants, requiring extensive chewing
  • Transitioning to higher-energy meat reduced the need for intense mastication, leading to changes in dentition and jaw size
  • Modern humans exhibit a U-shaped tooth arrangement
  • Archaic megadonts like Paranthropus robustus had robust jaws and large, thickly enameled teeth, suited for grinding tough vegetation
  • Pre-modern Homo species such as Homo floresiensis had relatively large teeth despite smaller stature, suggesting an omnivorous diet involving both plants and meat
  • Modern Homo sapiens have smaller teeth and less robust jaws, demonstrating further adaptations reflecting dietary shifts and technological advancements
• Hominid species discussed


  • Paranthropus robustus
  • Homo floresiensis
  • Homo sapiens
• Plant adaptations against herbivores - Structural

  • Thorns
  • Modified side branches (spines)
  • Divarication (branches at extreme angles to deter browsers)
  • Fibrous leaves (tough to digest)
• Plant adaptations against herbivores - Chemical

  • Capsaicin in fruits and seeds of chilli plants
  • Nicotine in tobacco plants
• Grass cells have tough cell walls which contain silica, making them difficult to chew
• Herbivores


  Consume predominantly plants for food
• Plant defences against herbivores

  • Plants have evolved many adaptations to prevent herbivores from consuming them
• Plant adaptations against herbivores - structural

  • Thorns
  • Modified side branches (spines)
  • Sharp trichomes on stinging nettles also contain irritating chemicals
  • Divarication (branches at extreme angles to deter browsers)
  • Fibrous leaves (tough to digest)
• Capsaicin


  Produced by chilli plants in fruits and seeds, causes a burning sensation in the digestive system of many herbivores
• Some birds and humans are not deterred by capsaicin
• Nicotine


  Toxin produced by tobacco plants, acts as a deterrent to herbivores
• The caterpillars of the tobacco hawk moth (known as tobacco hornworm) have evolved to detoxify nicotine and can feed on the tobacco plant
• Adaptations of grazing mammals

  • Flat molars for grinding grass
  • Teeth continue to grow throughout the life of the animal, so they do not become worn down
  • Bacteria and archea living in the rumen of ruminants help to break down cellulose
• Adaptations of chewing insects

  • Strong, sharp mandibles
  • Serrated edges to cut through the cell walls in the leaves of plants
  • Strong muscles to bite and grind leaves
• Piercing insects


  Piercing mouthparts allow them to feed on plants, e.g. aphids have stylets (hollow tubes) which they insert directly into the phloem of plants
• Predator adaptations


  • Sharp claws and talons
  • Powerful jaws and teeth
  • Speed and agility
  • Camouflage
• Venom


  Some predators have evolved chemical adaptations to kill prey, including the production of venom in glands
• Predator behavioural adaptations


  • Hunting in a pack
  • Ambush tactics
• Prey physical adaptations


  • Armour or protective coverings
  • Swift and agile
  • Camouflage
  • Mimicry