7.12 Variations in Populations

• Genetic diversity

  The different combination of alleles or genotypes and phenotypes found in a population
• Genetic diversity


  • Results from random mutations and crossing over during meiosis
  • Influences a population's ability to respond to changes in the environment
• Populations with little genetic diversity are at risk of extinction
• California condors

  • Had little genetic diversity
  • Became extinct in the wild in 1987
  • Threatened by habitat loss, poaching, and lead poisoning
• Genetically diverse populations


  • Are more resilient to environmental change
  • Are more likely to contain individuals who can withstand environmental pressures
• Environmental pressures (e.g. climate change, habitat loss, disease)

  Diverse populations are more likely to contain individuals adapted to withstand the changes
• Not all individuals in a diverse population are susceptible to a disease outbreak
• Antibiotic resistance

  An example of population resilience where some individuals can withstand exposure to antibiotics and pass on the resistance
• Deleterious traits


  Traits that reduce the chance of survival
• Adaptive traits


  Traits that increase chances for survival
• Selective pressures of the environment determine whether a trait is an advantage or disadvantage