natural selection

• define variation 


  differences that exist between individuals in a population
• what is most variation due to?

  different combinations of different alleles producing different phenotypes
• what are the environmental factors variation is caused by?

  climate change

  availability of food/water = animals

  intensity of light, availability of water and nutrients in soil = plants
• what are the genetic factors variation is caused by?

  Mutation

  meiosis

  fertilisation of gametes
• define species

  A group of similar organisms that can successfully breed together to produce fertile offspring
• define population


  a group of individuals of the same species in a particular habitat
• define evolution


  the change in allele frequency over many generations in a population.
• define selection pressures


  some organisms/ individuals will die or fail to reproduce due to predation, disease, or competition for resources
• What initiates the process of natural selection?

  Random mutations occur within a population
• What is the result of random mutations in a population?

  They cause genetic variation
• What do new alleles created through mutations provide?

  They provide an advantage to survive
• How does a new allele affect reproductive success?

  It provides a reproductive selective advantage
• What happens to individuals with advantageous alleles over generations?

  They are more likely to survive and reproduce
• What is the outcome of advantageous alleles being passed to offspring?

  It increases the frequency of the allele
• What does the increase in allele frequency result in for the species?

  Species become better adapted to their environment
• What does the change in allele frequency indicate?

  It indicates that evolution has occurred
• give 3 examples of evolution by natural selection

  1. antibiotic resistance
  2. peppered moths
  3. Darwin's finches
• define gene pool


  the total frequency of all the alleles of all the genes in a particular population at a given time.
• define species


  a group of similar organisms that can successfully breed together to produce fertile offspring
• define population


  a group of individuals of the same species in a particular habitat
• what is genetic diversity?

  the number of different alleles of genes in a population
• when does natural selection occur ?

  only occurs if there is genetic diversity within a population. and it leads to evolution in populations
• what are the steps of natural selection?

  1. new alleles are created by random mutations
  2. if the new allele increases survival chances the individual is more likely to reproduce
  3. so pass on the advantageous allele to the next generation
  4. over many generations this allele increases in frequency in the population causing evolution
• what does natural selection result in?

  species becoming better adapted to their environment
• What is the focus of the video by Mr. Stroke?

  Genetic diversity and natural selection
• What does genetic diversity refer to?

  The number of different alleles in a population
• What is necessary for natural selection to occur?

  Genetic diversity must be present
• What is the end result of natural selection?

  Evolution
• How is evolution defined in the context of natural selection?

  Change in allele frequency over generations
• How does natural selection affect allele frequency in a population?

  It changes the proportion of alleles over generations
• What happens to the allele frequency after natural selection?

  It results in better adaptation to the environment
• What are the three types of adaptations mentioned?

  Anatomical, physiological, and behavioral
• What does anatomical adaptation refer to?

  Structural features of an organism
• What is physiological adaptation related to?

  Chemical reactions within the body
• What does behavioral adaptation involve?

  How an organism behaves to survive
• What is the process of natural selection?

  1. Genetic diversity exists in a population.
  2. New alleles arise from random mutations.
  3. Advantageous alleles increase survival chances.
  4. Individuals with advantageous alleles reproduce.
  5. Over generations, allele frequency changes.
• How does fur color in mice illustrate natural selection?

  Dark fur provides a selective advantage
• How does eyesight in owls relate to natural selection?

  Good eyesight increases hunting success
• What are the two types of natural selection?

  1. Directional selection

  • One extreme trait has a selective advantage.
  • Occurs with environmental changes.

  1. Stabilizing selection

  • The modal trait remains advantageous.
  • Occurs without environmental changes.
• What is directional selection?

  One extreme trait has a selective advantage