Reproduction in Animals

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Reproduction in Animals
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Reproduction

• All animals must reproduce for the species to
  survive
• May reproduce sexually or asexually
• Sexual Reproduction
• Disadvantage Longer
• Advantage Genetic Diversity
• Asexual Reproduction
• Disadvantage No genetic diversity, identical to
  parent
• Advantage Quick Efficient

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Sexual Reproduction Overview

• Sexual Reproduction Production of offspring from
  the fusion of gametes
• Gametes are haploids (1N)
• Gametes are produced by meiosis
• Fertilization process of two gametes (egg
  sperm) fusing together resulting in a zygote

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Sexual Reproduction Overview

• Usually the sexes are separated into separate
  individuals
• One produces the eggs - Female
• One produces the sperm - Male
• Hermaphrodites produce both sperm and eggs.
• Earthworms
• External fertilization Outside the body
• Internal fertilization Inside the body

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Sexual Reproduction Development

• Animals that reproduce sexually begin life as a
  zygote (fertilized egg)
• Zygote will undergo a series of divisions and
  form a blastula (hollow ball of cells)
• Blastula will form a hole known as a blastopore
• Protosome the hole, blastopore, will become the
  mouth
• Deuterostome the hole, blastopore, will become
  the anus

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Asexual Reproduction

• Organisms grow into multicellular organisms
  through mitosis
• Same genetics as parent
• Happens quickly
• Budding

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Budding!
Asexual
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Invertebrate Reproduction

• Most invertebrates reproduce sexually during at
  least part of their life cycle
• Depending on environmental conditions, many
  invertebrates may also reproduce asexually

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Chordate Reproduction

• Almost all reproduce sexually
• General trend from external to internal
  fertilization
• Fishes Amphibians External
• Birds, Reptiles, Mammals - Internal

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Chordate Development

• Development in Chordates can follow three general
  patterns.
• Oviparous
• Eggs develop outside the body
• Fishes, Amphibians Birds
• Ovoviviparous
• Eggs develop within the mothers body
• Embryos receive nutrients from the yolk in the
  egg
• Young are born alive
• Sharks
• Viviparous
• Nutrients are obtained directly from mothers
  body
• Young are born alive
• Mammals