ANIMAL REPRODUCTION

• Types of reproduction

  • Asexual
  • Sexual
• Asexual reproduction


  • Offspring are genetically identical to the parent
• Fission (binary fission)

  Prokaryotic microorganisms split into two separate organisms
• Budding


  Results from the outgrowth of a part of a cell or body region leading to a separation from the original organism into two individual organisms
• Organisms that undergo budding

  • Coral
  • Hydra
• Fragmentation


  • Breaking the body into two parts with subsequent regeneration
  • Fragmentation forms a completely new organism
  • Regeneration repairs the damaged parts
• Parthenogenesis


  An egg develops into a complete individual without being fertilized
• Sexual reproduction


  • Combination of haploid reproductive cells from two individuals to form a unique diploid offspring
• Hermaphroditism


  • One animal has both male and female parts
  • This may occur individually or with others, resulting in two offspring
• Separate sexes

  • Can be determined by a set of chromosomes (XX for male, XY for females in humans)
  • Can be determined by the z and w chromosomes in avians
  • Can be determined by environmental sex determination for other species (e.g. turtles giving birth to males during cold season and females during hot)
• Sex reversal


  An organism can change their sex from male or female
• Protogyny


  Organisms that are female first
• Protandry


  Organisms that are male first