Reproduction and Development

• Internal fertilization

  • Requires behavioral interactions and compatible copulatory organs
• Fertilization


  • Requires critical timing, often mediated by environmental cues, pheromones, and/or courtship behavior
• Fertilization


  Mechanisms that bring together sperm and eggs of the same species
• Internal fertilization

  Sperm are deposited in or near the female reproductive tract, and fertilization occurs within the tract
• External fertilization


  • Eggs shed by the female are fertilized by sperm in the external environment
• Internal fertilization requires behavioral interactions and compatible copulatory organs
• All fertilization requires critical timing, often mediated by environmental cues, pheromones, and/or courtship behavior
• Fertilization is based on mechanisms that bring together sperm and eggs of the same species
• In internal fertilization, sperm are deposited in or near the female reproductive tract, and fertilization occurs within the tract
• In external fertilization, eggs shed by the female are fertilized by sperm in the external environment
• Asexual Reproduction (Plantae)

  • vegetative reproduction (propagation)
  • apomixis
• Stems - runners are the stems which usually grow in a horizontal form above the ground. They have the nodes where the buds are formed. These buds usually into a new plant.
• vegetative reproduction


  new plants are produced from the vegetative parts of the plants
• Vegetative propagation in plants can occur both naturally or also can be artificially induced by horticulturists.
• Leaves - detached leaves from the parent can be used to grow a new plant. They exhibit growth of small plants, called plantlets, on the edge of their leaves.
• Roots - a new plant is developed from modified roots called root tubers (ex. potato and cassava)
• Stem - a new plant is developed from modified stem called stem tubers (ex. ginger and potato)
• Modes of Vegetative Reproduction

  • Budding
  • Fragmentation
• Budding


  a new plant is developed from an outgrowth known as the bud
• Fragmentation


  a new plant is produced from a portion of the new parent plant
• In fragmentation, each section or a part of the plant develops into a mature, fully grown individual.
• Apomixis


  an asexual reproduction that occurs without fertilization but produces embryo and seed
• Asexual Reproduction (Animalia)

  • Fission
  • Budding
  • Fragmentation and Regeneration
  • Parthenogenesis
• Budding - occurs in some invertebrates (hydra, corals); outgrowth of a part of a cell or body region leading to a separation from the original organism into two individuals.
• fragmentation and regeneration

  breaking of body into two parts with subsequent regeneration
• Fragmentation and regeneration occurs in sea stars, annelid, worms, turbellarians, and poriferans.
• Fission (Binary Fission)

  splits into two separate organisms
• Fission occurs in prokaryotic organisms and in some invertebrates (ex. sea anemone)
• Types of Fission

  • longitudinal
  • transverse
  • irregular
• Parthenogenesis


  an egg develops into complete individual without being fertilized
• Parthenogenesis occurs in invertebrates.

  • water fleas
  • rotifers
  • aphids
  • stick insects
  • wasps
  • bees
  • some ants
• Sexual reproduction results in genetic recombination, which provides potential advantages.
• Non-flowering plants can reproduce by spores.
• A parent plant sends out tiny spores containing special sets of chromosomes. Fertilization of the spores takes place away from the parent, usually in damp place.
• The flower is the reproductive organ of flowering plants.
• Flowers are especially designed to attract specific pollinators and/or disperse pollen.
• Flowers may be perfect or imperfect.
• Imperfect flowers may be staminate or pistillate/carpellate.
• perfect flower

  • stamen - male reproductive organ (anther, filament)
  • pistil - female reproductive organ (stigma, style, ovary)
• imperfect flower - either just male or female reproductive organ