3- Factors Affecting Biodiversity

• Genetic biodiversity


  The diversity of genes within a species or population
• Increasing genetic biodiversity


  1. Random mutations creating new alleles

  2. Migration between populations transferring alleles
• Gene flow


  The transfer of alleles between populations
• Decreasing genetic biodiversity


  1. Natural selection favoring advantageous alleles

  2. Selective breeding removing less advantageous alleles

  3. Populations crashing to low levels (genetic bottleneck)

  4. Isolated populations with limited diversity (founder effect)

  5. Random chance (genetic drift)
• Selective breeding


  • Cattle
  • Crops
• Rare breed


  • Manx Loaghtan sheep
• There are only around 400 Sumatran Tigers left in the wild
• There were around 200 Sumatran Tigers in zoos
• The black Robin population collapsed to only 5 individuals, including 1 fertile female
• The black Robin population has increased to around 300 individuals
• Genetic bottleneck


  When a population crashes to an extremely low level, severely reducing genetic diversity
• Founder effect


  When a small number of individuals form an isolated population, limiting genetic diversity
• Wolves first arrived on Isle Royale in 1949 from the mainland
• Genetic drift is the random loss of alleles due to chance events in small populations</b>