MS5- metabolism in adverse conditions

• Many environments vary beyond the tolerable limits for normal metabolic activity for an organism.
• Some animals have adapted to survive these adverse conditions while others avoid them
• Dormancy is part of some organisms' life cycle to allow survival during a period when the costs of continued metabolic activity would be too high
• The metabolic rate can be reduced during dormancy to save energy
• During dormancy there is a decrease in:

  • metabolic rate
  • heart rate
  • breathing rate
  • body temperature
• Dormancy can be predictive or consequential
• Predictive dormancy occurs in predictable environments before the onset of adverse conditions
• Consequential dormancy occurs in unpredictable environments after the onset of adverse conditions
• Some mammals survive during winter/low temperatures by hibernating (usually predictive)

  for example, bear, dormouse, bat hedgehog
• Aestivation allows survival in periods of high temperature or drought (usually consequential)

  for example, snail, frog, crocodile
• Daily torpor is a period of reduced activity/metabolic rate in some animals with high metabolic rates- hummingbird
• It allows energy to be conserved for other activities
• Torpor frequency can be affected by daily food intake, temperature and day length
• Migration is a behaviour used to avoid adverse conditions/ metabolic diversity/ lack of food by relocating to a more suitable environment
• Energy is expended during migration; it thus has a high metabolic cost
• Migratory behaviour can be innate and learned
• Innate behaviour is:

  • inherited
  • carried out by all individuals in a species
  • triggered by external stimulus- eg photoperiod
  • inflexible
• The timing and direction of migration are examples of innate behaviour
• Learned behaviour is:

  • developed as a result of experience. eg watching others/ trial and error
  • flexible
• Stopover feeding sites and alterations to the route are based on the experience of previous migrations and thus learned behaviours
• Specialised techniques like satellite tracking and leg rings are used to study long distance migration