Sexual Animal Reproduction

• Sexual Reproduction

  • creation of offspring by the fusion of haploid gametes to form a zygote (fertilized egg), which is diploid.
  • Relatively slow
• Gametes

  • Female - the unfertilized egg (ovum), is a relatively large cell and not motile.
  • Male - the sperm, is generally much smaller, motile cell
• Advantages

  • Increases genetic variability among offspring by generating unique combinations of genes inherited from two parents.
  • May enhance the reproductive success of parents when environmental factors change relatively rapidly,
• Mechanisms of Sexual Reproduction

  1. Internal Fertilization
  2. External Fertilization
• Internal Fertilization

  • the fusion of sperm and egg may take place inside the body. The male generally delivers sperm cells directly into the body of the female. Her moist tissues provide the watery medium required for the movement of sperm.
• External Fertilization

  • Mating partners usually release eggs and sperms into the water simultaneously..
• Reproductive Variations

  • Metagenesis
  • Parthenogenesis
  • Hermaphroditism
• Metagenesis

  • also known as 'transformative development', it is the alteration of asexual and sexual generations.
• Parthenogenesis

  • also known as 'virgin development', is a form of reproduction in which an unfertilized egg develops into an adult animal.
  • This occurs for several generations, after which males develop, produce sperm, and mate with females to fertilize their eggs.
• Hermaphroditism

  • a single organism produces both eggs and sperm.