Reproductive Strategies

• Asexual reproduction is the ability to produce new offspring without having to find a mate.
• Vegetative Propagation


  A type of asexual reproduction in plants that occurs through the mitosis of undifferentiated cells of meristematic tissue. E.g. Strawberries
• Budding


  A form of asexual reproduction where a new organism develops, through cell division, from an outgrowth on the parent. E.g. Sponges
• Fragmentation


  An organism is split into fragments and each fragment can develop into a mature organism. E.g. Starfish
• Parthenogenesis


  An unusual form of asexual reproduction in animals which is also referred to as 'virgin birth'. The embryo can develop without fertilisation. E.g. Komodo dragons.
• Advantages of Asexual Reproduction


  • Able to quickly colonise an area
  • Reproduce without wasting time and energy finding a mate
  • Organisms are usually well-suited to the environment
• Disadvantages of Asexual Reproduction


  • Lack of genetic variation
  • Places pressure on the availability of resources
  • If conditions in that environment were to change, entire population can be lost
• External Fertilisation


  When animals release their gametes into the external environment so that fertilisation occurs outside the body of females
• Internal Fertilisation


  Occurs when males deliver sperm directly into the reproductive tract of females so that fertilisation of eggs occurs inside the body of females.
• Advantages of Sexual Reproduction


  • Genetic diversity within the species
  • Genetic variation increases chances of survival if environment to change
  • More traits to select for when choosing a mate, allows for natural selection to occur
• Disadvantages of Sexual Reproduction


  • Wastes time and energy to find a mate
  • Some organisms can be injured/killed in competition for a mate
• Embryo Splitting


  Cloning by embryo splitting occurs when the cells of an early embryo are artifically separated, typically into two cell masses.
• Embryo Splitting


  • Parents are chosen for desirable characteristics
  • Embryos are split by IVF
  • Embryos are split at an early stage of development
  • The split embryos are identical to each other
• Somatic Cell Nuclear Transfer


  The nucleus of an egg cell is removed (enucleated) and the DNA from a somatic cell is fused into the enucleated egg cell with a short electrical pulse. Offspring will be identical to that of donor of the somatic cell's DNA.
• Cloning has shown that adult somatic cells can be totipotent