genetic diversity

• How can we assess genetic diversity?

  proportion of polymorphic gene loci = number of polymorphic gene loci/ total number of loci
• What are benefits of genetic diversity?

  allows for adaptation to changing environment

  provides variation for natural selection

  can offer, camouflage / protection from predators
• What are the 3 main things that reduce genetic biodiversity?

  captive breeding

  inbreeding

  genetic bottlenecks
• How does captive breeding reduce genetic biodiversity?

  animals and plants kept in zoos, there is only a small number of individuals and so they'll be breeding together often, thus reducing the size of the gene pool and so the same alleles will keep being passed on
• What is a genetic bottleneck?

  when a small number of a population have survived an event such as a natural disaster, or new disease -rest of the population have died out and thus they've lost all of the alleles that were in the population that died out

  this reduces the size of the gene pool as there's only a certain number of individuals present and only the alleles that those individuals have can be passed on to future generations
• What is the founder effect?

  from an original population a small number migrate to an isolated area

  thus whichever alleles those individuals have are the only ones present

  and you're likely going to get inbreeding as there's a small number of individuals thus will reproduce together and continue to pass on the same alleles
• How is genetic diversity calculated?

  by examining polymorphic genes within isolated populations such as zoos (captive breeding), rare breeds and pedigree animals where selective breeding has been used
• What is a polymorphic gene?

  A gene that has more than one allele
• What are monomorphic genes?

  Genes with only one allele

  most genes within a population are monomorphic
• What does the proportion of polymorphic gene loci tell us?

  the higher the proportion of polymorphic gene loci, the larger the genetic diversity within the population
• What is the problem if a population has low genetic diversity?

  they may not be able to adapt to a change in the environment and thus the whole population could be wiped out by a single event e.g a new disease
• Why is it beneficial if a population has genetic variation ?

  there is a wider range of alleles within the population, thus this increases the likelihood that some organisms will be suited to a change in environment, some organisms will be better adapted

  thus there is a lower probability of all organisms being killed by the disease
• alleles of the same gene are found at the same point (a locus) on a chromosome

  polymorphism describes a locus that has 2 or more alleles