Genetic diversity

• definition of genetic diversity

  number of different alleles of genes in a population
• how do mutations affect genetic diversity

  mutation can result in forming of new alleles and contribute to size of gene pool
• what is phenotype 


  the set of observable characteristic of an individual resulting from interaction of its genotype with the environment
• affect of different alleles on natural selection and environment

  different alleles possessed by individuals result in different phenotypes.

  environmental factors increase chance of individuals with desired phenotype surviving and can reproduce passing trait down . described as having a higher fitness
• disadvantage of populations having small gene pool

  has lower genetic diversity

  much less able to adapt to environmental changes

  more likely to face extinction
• what is founder effect

  when only a small number of individuals from a large parent population start a new population .

  only some of total alleles from parent population present .
• what is genetic drift

  if a population is significantly small , chance can determine which alleles get passed onto next generation . overtime some alleles can be lost forever or favoured.
• what is bottleneck effect

  occurs when a previously large population suffers dramatic fall in numbers

  major environmental effect can reduce numbers of individuals in population and reduce genetic diversity as alleles are lost

  surviving individuals breed and reproduce with close relatives.
• definition of natural selection

  random nutation produces new alleles of gene .

  can provide survival advantage and more likely to reproduce than those without

  advantageous alleles passes onto new generation
• what are selection pressures

  environmental factors that affect the chance of survival of an organism. e.g high competition of food between predators when there is not enough prey
• what are two types of natural selection

  stabilising and directional
• what is stabilising selection 


  natural selection keeps allele frequencies relatively constant over generation . stays the same unless change i environment. e.g. human birth rate
• what is directional selection

  selection that produces a gradual change in allele frequencies over several generations

  usually happen if there is a change in environmental / selection pressures or a new advantageous allele has appeared. e.g. antibiotic resistance bacteria strains becoming more common due to antibiotic overuse
• what type of selection is antibacterial resistance

  is a sectional pressure ,

  mutation occurs in bacteria population random

  gives rise to beneficial allele

  mutated bacteria more likely to survive and reproduces

  bacteria without mutation dies off and over generation mutation of beneficial allele increases
• What is a adaptation 


  When certain alleles within a species population can produce features that make an organisms better suited to environment
• what is a anatomical adaptation

  structural or physical feature that provides a advantage
• what is a physiological adaptation

  a biological process within a organism that provides a advantage . e.g mosquitoes produce chemicals that stop animal blood from clotting
• what is a behavioural advantage 


  the way an organisms behaves for survival