Natural selection

• Natural selection

  • When an allele codes for a characteristic that increases chances of an organism surviving, its frequency within a population increases
• Process of natural selection

  1. There is differential reproductive success in a population, individuals with an allele increasing chances of survival, more likely to survive, reproduce and pass on their genes unlike less advantageous alleles.
  2. = greater proportion of next generations inherits the beneficial allele
  3. so more likely to survive, reproduce and carry on their genes
  4. frequency of beneficial allele increases from generation to gen
  5. leading to evolution as advantageous alleles become fore common in population
• Behavioural adaptations

  • Ways an organism acts to increase chances of survival
  • Possums 'play dead' if threatened by predator, increasing chance of survival
  • scorpions dance before mating, to attract mate of same species, increasing likelihood of successful mating
• Physiological adaptations

  • processes inside an organisms body
  • brown bears hibernate, lower metabolic rate over winter to conserve energy, don't need to look for food in months when scarce.
  • Bacteria produce antibiotics, kill other species of bacteria in area, less competition
• Anatomical (structural) ADAPTATIONS

  • Structural features
  • Otters, streamlined shape, easier to glide through water to catch prey and escape predators
  • whales thick layer of blubber (gorg) helps to keep them warm in cold sea.