B4.1

• Habitat


  The place in which a community, species, population or organism lives
• Habitat


  • Can include both geographical and physical locations, and the type of ecosystem
• Adaptation


  A genetic change that increases an organism's chance of survival and reproduction in a particular environment
• Abiotic variables affecting species distribution

  • Temperature
  • Water availability
  • Light (intensity/wavelength)
  • Soil pH
  • Soil salinity
  • Mineral nutrient availability
• Abiotic variables affecting plant species distribution

  • Temperature: Metabolic pathways controlled by enzymes with optimal temperatures, high temperatures increase evaporation
  • Water: Needed for cell turgor, photosynthesis and respiration, xerophytes and hydrophytes adapted
  • Light: Intensity and wavelength limit photosynthesis, shade plants have more chlorophyll
  • Soil pH: Affects mineral nutrient availability
  • Soil salinity: High salinity makes water uptake difficult, halophytes adapted
  • Mineral nutrients: Affect plant fertility, availability affected by soil conditions
• Abiotic variables affecting animal species distribution

  • Temperature: Must be within viable range, homeotherms can colonise wider range
  • Water: Required for drinking, habitat, transport, breeding, cooling
  • Breeding sites: Provide protection, resources for juveniles
  • Food availability: Critical for population size, some species specialised
  • Territory: Established for mating, rearing young, foraging, avoiding predators
• Factors affecting species distribution

  • Southern right whales migrate long distances for food supply
  • Tigers require large territories
• The distribution of species is affected by limiting factors
• Territory


  • Not all animals are territorial, but those that may do so to attracting mates, rearing young, forage for food or to avoid predators
  • Animals may mark territories, e.g. by urinating or marking trees
  • Territories can be established by individuals, breeding pairs or groups
  • Territories maybe temporary (e.g. just for the duration of breeding cycle) or permanent
  • Establishment of territories can lead to intra-specific (within species) or inter-specific (between species) competition
• Detail on how the factors affecting the distribution of animal species
• Although it is unlikely you will need to learn all of these details understanding the concepts will enable you to better communicate your examples
• Abiotic variables affecting species distribution


  Example factors affecting the distribution of species
• Southern right whales


  • Migrate from their Antarctic feeding areas to temperate breeding areas along the costs of Chile and Argentina, southern Africa, and Australia and New Zealand, covering 2,500 km each way
  • Their migration is fuelled entirely by fat accumulated during their four-month stay in the icy Southern Ocean around Antarctica, where they skim the surface waters for zooplankton
  • They will not feed until their return a year later
• Territory availability and distribution of animals

  • Tigers are solitary animals that require large territories, the size of which is determined mostly by the availability of prey
  • A tiger's territory consists of forest, to shelter their prey, and access to water
  • Although individuals do not patrol their territories, they visit over a period of days or weeks and mark their territory with urine and feces
  • Their habitat has been lost to growing human populations which require land for agriculture. Both the size of forest patches has decreased, some are too small to support individual tigers and total size of habitat has decreased lowering the maximum population size
• Shelford's law of tolerance


  • A useful tool to understand the relative abundance of a species and hence predict community structure
  • It plots the range of a biotic or abiotic factor that is tolerated by a species
  • Because there is variability within a population the limits of tolerance and where the zones of stress start is not always easy to measure
• Tolerance range


  The range of the condition in which the organism can survive and function optimally
• Limiting factor


  When the abiotic factor limits growth/ population size of an organism
• Using sensors to measure abiotic factors (PLC)
• Black mangrove (Avicennia germinans)

  • It can survive and grow in a wide range of salinity levels from 0 to 96 part per thousand (ppt)
  • Greatest growth rates occur at salinity levels of 24 and 48 ppt, the optimal zone, outside of this range the Black Mangrove trees experience the zones of stress
• The red dots show the global distribution of coral reefs
• The blue band shows where water temperatures are in excess of 20°C
• Coral reef


  The end result of a symbiotic relationship between coral polyps (the calcified skeletons of tiny invertebrate animals) and a microscopic algae called zooxanthellae
• Coral reefs are described as being dynamic, what do you think this means?
• Coral provides the algae with


  • A protected environment - coral polyps secrete calcium carbonate to build the stony skeletons which house the coral polyps (and zooxanthellae)
  • Compounds they need for photosynthesis
• Algae provide the coral with

  • Oxygen
  • Help the coral to remove wastes
  • Supplies the coral with glucose, glycerol, and amino acids (products of photosynthesis)
• The relationship between the algae and coral polyp facilitates a tight recycling of nutrients in nutrient-poor tropical waters
• Zooxanthellae are responsible for the unique and beautiful colors of many corals
• Mutualistic relationship is an association between organisms of two different species in which each member benefits
• Photosynthesis pathways in zooxanthallae are impaired at temperatures above 30°C therefore for most corals the upper limit of tolerance is 30°C
• The maps show that for most coral species that the limits of tolerance for most species is approximately 20°C
• Abiotic factors required for Coral formation


  • Water depth
  • Salinity
  • pH
  • Water clarity
  • Temperature
• Coral reef bleaching, the whitening of diverse invertebrate taxa, results from the loss of symbiotic zooxantheallae and/or a reduction in photosynthetic pigment concentrations in zooxanthellae. It's the result of rising water temperatures
• Abiotic factors required for Coral formation

  • Shallow water where sunlight can easily penetrate and reach algae
  • Stable salt concentration (30-37 parts per thousand) needs to be salty to build a coral reef
  • Slightly alkaline to allow calcium to be deposited in calcium carbonate exoskeleton
  • Must be clear to enable light to easily pass through to ensure survival of algae
  • Optimum between 23-29°C. Coral can't tolerate below 18°C
• Adaptations organisms living in a coral reef have

  • Symbiotic relationship
  • Camouflage
  • Unique colour patterns to allow them to blend in and avoid predators
  • Protective covering
  • Stingers and spines
  • Reproductive strategies
• Biome


  A geographical area that has a particular climate conditions and sustains a specific community of plants and animals (i.e. a type of ecosystem)
• Biosphere


  The total of all areas where living things are found (i.e. the totality of biomes)
• Savanna


  A type of grassland that includes scattered trees
• Main factors affecting the distribution of biomes

  • Temperature
  • Rainfall
• Temperature is influential because it affects the rate of metabolism – the phases in the life cycles of many organisms are temperature dependent
• The availability of fresh water (both in the soil and in rivers and lakes) is critical to the growth and nutrition of organisms