The Adaptions of Organisms

• For many people the image of a polar bear and ice caps epitomises life in the Arctic
• The poler bor is ideally adopted for life as polar regions, an environment which betic to the vast majority of quicles on Earth
• Adaptations of the polar bear


  • White colouration for camouflage
  • Thick fur for insulation
  • Short tail to reduce heat loss
  • Ability to swim considerable distances when hunting seals
  • Keen sense of smell to detect their prey
• The polar bear occupies a habitat typical for (most mammals are found in temperate warmer areas), so has many ubwirus adaptations
• All species are adapted in some way f the emimement in which they are normally found
• Types of adaptations


  • Behavioural
  • Physiological
  • Morphological
• Ecological factors


  • Climatic
  • Edaphic (soil)
  • Biotic
• Climatic factors


  Factors related to climate that influence the distribution of organisms
• Climatic factors


  • Temperature range
  • Availability of water
  • Light intensity
  • Light quality
  • Day length
• Edaphic factors


  Factors related to soil that influence the distribution of organisms
• Edaphic factors


  • pH values
  • Availability of nutrients
  • Water content
  • Aeration of soils
• Biotic factors


  Factors related to interactions between living organisms that influence their distribution
• Biotic factors


  • Competitors
  • Predators and prey
  • Accumulation of waste
• The ecological factors (climatic, edaphic and biotic) affect both the distribution of organisms and also determine the number of individuals that a particular environment can support
• Ecological niche


  An organism's role within the ecosystem, including its role in the food chain, its climatic and (if relevant) edaphic requirements, and its competition with other organi
• Wild garlic is a common plant occurring in deciduous woodlands (for example, oak, ash and beech) with moist soils throughout most of lowland British Isles
• Wild garlic grows particularly well on nutrient rich woodland soils with a pH value around neutral
• Wild garlic cannot grow in waterlogged soil as the bulbs cannot survive if the ground is waterlogged and therefore not aerated for too long a period of time
• Wild garlic grows in dense colonies with very few other plants present in the habitat at this stage of the year
• Wild garlic is virtually unique in that it can growin very low light intensities, such as the light levels found at the edges and partially under rhododendron trees
• Adaptations of wild garlic to low light


  • Ability to develop very thin leaves
  • Cuticle with microscopic pyramid structures that concentrate and refract light onto the palisade layer
• You do not need to know the details of wild garlic as described on page 183, but through the 'study of organisms in their habitat" you should have a good understanding of and be able to interpret the adaptations that allow organisms to survive in a range of habitats, and the ecological factors that impact on their distribution and success
• Sampling


  Estimating the number or distribution of plant or animal species in a habitat by studying a representative sample rather than the entire habitat
• You are expected to be familiar with a range of qualitative and quantitative techniques used to investigate the distribution and relative abundance of plants and animals in a habitat
• Sampling


  It is normally not possible, or at least not efficient, to count all the individuals of one a range of species in a habitat. Instead, the habitat is usually sampled to gain an accurate estimate of plant or animal species numbers, or their distribution
• Ways to estimate the abundance of organisms


  • Density - the number of individuals present
  • Percentage cover - Mainly used for plants, gives an estimation of the percentage area of the quadrat covered by a plant species
  • Frequency - At each sampling point (for example, quadrat) each species is recorded as being present or absent
• Mechanisms of sampling


  1. Random sampling - If the area to be sampled is uniform or if there is absence of any clear pattern in species distribution, then random sampling should normally be used

  2. Systematic sampling - In certain conditions sampling should not be totally random but should be systematic, for example, up a river bank, from a woodland edge to the centre of the wood or up a seashore
• Types of transect used in systematic sampling


  • Line transect - Sampling either continually or at intervals along a transect line
  • Belt transect - Sampling along a transect line using quadrats, typically placed end to end to each other
  • Interrupted belt transect - As for the belt transect, but the sampling is at intervals along the overall transect
• Abiotic factors


  Non-living or physical factors, for example, soil moisture, soil organic content, soil temperature, soil pH and light intensity
• Biotic factors


  Factors linked to living organisms, for example, competition from other organisms, grazing, predation
• Measuring soil moisture (water) content


  Collect a soil sample, weigh it, dry it in an oven, and reweigh to calculate the percentage soil moisture content
• Measuring soil organic content


  Place the oven dried soil in a crucible, burn off the organic content, allow to cool, and reweigh to calculate the percentage organic content
• Measuring soil pH


  Use a soil testing kit or a pH electrode attached to a digital meter
• Measuring soil temperature


  Use a soil thermometer, ensuring the bulb is lowered to the same depth at different sampling points
• Measuring light intensity


  Use a light meter, often measuring relative light intensity (light at ground level as a percentage of light in the open)
• Pitfall traps


  Used to capture small animals that walk over the habitat surface, for example, woodland floor
• Sweep nets


  Used to sample arthropods in tall grass, by sweeping the net from side to side through the grass
• Pooters


  Used to capture small insects for bringing back to the laboratory for identification and counting
• Ecological data is usually recorded in tables and presented in graphs, with the type of graph used depending on the data collected