Factors Affecting Evolution

• What are environmental factors that affect survival called?

  Selection pressures
• How does high competition for food affect lions?

  It selects for faster, more powerful lions
• What is the effect of selection pressures on allele frequencies?

  They change allele frequencies through natural selection

  
• What are the two main types of selection in evolution?

  • Stabilising selection
  • Directional selection
• What does stabilising selection do to allele frequencies?

  It keeps them relatively constant over generations
• What happens to very-low and very-high birth weights in stabilising selection?

  They are selected against

  
• What does directional selection produce over generations?

  A gradual change in allele frequencies

  
• When does directional selection usually occur?

  When there is a change in environment
• What is required for directional selection to occur?

  Phenotypic variation within a population
• What happens to individuals with the favored phenotype in directional selection?

  They are fitter and more likely to reproduce
• What is the effect of climate change on fish size?

  It selects for smaller body size

  
• Why are organisms sensitive to temperature changes?

  Temperature affects enzyme activity
• How does fish body size relate to genetic and environmental factors?

  Both genetic and environmental factors determine size
• What happens to allele frequencies over generations in directional selection?

  Advantageous alleles increase, others decrease

  
• What are other factors that can affect evolution?

  • Genetic drift
  • Genetic bottleneck
  • Founder effect
• What is genetic drift?

  Chance affects which individuals survive and breed

  
• How does genetic drift affect small populations?

  Chance can significantly alter allele frequencies

  
• Why is genetic drift less likely in large populations?

  Chance variations even out across the population
• What is the bottleneck effect?

  A dramatic fall in population numbers reduces diversity
• How does the bottleneck effect impact breeding?

  Surviving individuals breed with close relatives
• What happened to cheetah populations after the Ice Age?

  They experienced a lack of genetic variation
• Why is genetic variation important for conservation?

  It helps species survive environmental changes
• What is the Founder effect?

  Small number of individuals start a new population
• How does the Founder effect affect allele frequencies?

  Changes may occur in a different direction

  
• What is a gene pool?

  The complete range of DNA sequences in a population
• How do Anole lizards demonstrate the Founder effect?

  They carry a small selection of alleles to new islands
• What can happen to scale color in lizards due to the Founder effect?

  New populations may only have white scales
• What processes affect allele frequencies?

  • Natural selection
  • Genetic drift
  • Genetic bottleneck
  • Founder effect

  
• What is the significance of the processes affecting allele frequencies?

  They influence the evolution of species

  
• What is the main role of natural selection in large populations?

  It has a much more influential role
• What is the relationship between selection pressures and evolution?

  Selection pressures drive evolutionary changes
• How does the environment exert selection pressure on organisms?

  By influencing survival and reproduction
• What is the impact of warmer seas on fish metabolism?

  It speeds up metabolism and increases oxygen needs
• How does the bottleneck effect relate to genetic diversity?

  It reduces genetic diversity in populations
• What is the effect of inbreeding after a bottleneck event?

  It leads to reduced genetic variation
• What can happen to allele frequencies in a small population due to genetic drift?

  Some alleles can be lost or favored by chance

  
• How does the Founder effect influence the genetic makeup of a new population?

  It may lead to a different allele frequency direction
• What is the relationship between allele frequencies and evolutionary processes?

  Changes in allele frequencies indicate evolution