genetic hitchhiking

Examples of genetic hitchhiking in the following topics:

• Defining Population Evolution

  • Genetic variation in a population is determined by mutations, natural selection, genetic drift, genetic hitchhiking, and gene flow.
  • Five forces can cause genetic variation and evolution in a population: mutations, natural selection, genetic drift, genetic hitchhiking, and gene flow.
  • Even in the absence of selective forces, genetic drift can cause two separate populations that began with the same genetic structure to drift apart into two divergent populations.
  • Therefore, the frequency of a gene may increase in a population through genetic hitchhiking if its proximal genes confer a benefit.
  • Describe how the forces of genetic drift, genetic hitchhiking, gene flow, and mutation can lead to differences in population variation

• No Perfect Organism

  • Therefore, the process of evolution is limited by a population's existing genetic variance, the physical proximity of alleles, non-beneficial intermediate morphs in a polymorphic population, and non-adaptive evolutionary forces.
  • When a neutral allele is linked to beneficial allele, consequently meaning that it has a selective advantage, the allele frequency can increase in the population through genetic hitchhiking (also called genetic draft).
  • While natural selection selects the fittest individuals and often results in a more fit population overall, other forces of evolution, including genetic drift and gene flow, often do the opposite by introducing deleterious alleles to the population's gene pool.
  • It is simply the sum of various forces and their influence on the genetic and phenotypic variance of a population.

• Genetic Variation

  • Genetic variation is a measure of the variation that exists in the genetic makeup of individuals within population.
  • Genetic variation is a measure of the genetic differences that exist within a population.
  • The genetic variation of an entire species is often called genetic diversity.
  • New genetic variation can be created within generations in a population, so a population with rapid reproduction rates will probably have high genetic variation.
  • Populations of wild cheetahs have very low genetic variation.

• Genetic Engineering

  • In genetic engineering, an organism's genotype is altered using recombinant DNA, created by molecular cloning, to modify an organism's DNA.
  • Genetic engineering is the alteration of an organism's genotype using recombinant DNA technology to modify an organism's DNA to achieve desirable traits.
  • The organism that receives the recombinant DNA is called a genetically-modified organism (GMO).
  • " This technique, called reverse genetics, has resulted in reversing the classic genetic methodology.
  • Borer-resistant corn is an example of a genetically- modified organism made possible through genetic engineering methods that allow scientists to alter an organism's DNA to achieve specific traits, such as herbicide resistance.

• Genetic Drift

  • Genetic drift is the converse of natural selection.
  • Small populations are more susceptible to the forces of genetic drift.
  • In a population of 100, that individual represents only 1 percent of the overall gene pool; therefore, genetic drift has much less impact on the larger population's genetic structure.
  • The genetic structure of the survivors becomes the genetic structure of the entire population, which may be very different from the pre-disaster population.
  • Thus even while genetic drift is a random, directionless process, it acts to eliminate genetic variation over time.

• Biotechnology in Medicine

  • Knowledge of the genetic makeup of our species, the genetic basis of heritable diseases, and the invention of technology to manipulate and fix mutant genes provides methods to treat the disease.
  • It is, therefore, the study of the relationship between pharmaceuticals and genetics.
  • The process of testing for suspected genetic defects before administering treatment is called genetic diagnosis by genetic testing.
  • Genetic testing involves the direct examination of the DNA molecule itself.
  • Gene therapy is a genetic engineering technique used to cure disease.

• Genetic Maps

  • Genetic maps provide information about which chromosomes contain specific genes and precisely where the genes lie on that chromosome.
  • The mapping of genes relative to each other based on linkage analysis led to the development of the first genetic maps.
  • Early genetic maps were based on the use of known genes as markers.
  • Some genetic markers used in generating genetic maps are restriction fragment length polymorphisms (RFLP), variable number of tandem repeats (VNTRs), microsatellite polymorphisms, and the single nucleotide polymorphisms (SNPs).
  • Describe the different types of genetic markers that are used in generating genetic maps of DNA

• Physical Maps and Integration with Genetic Maps

  • A physical map provides detail of the actual physical distance between genetic markers, as well as the number of nucleotides.
  • It is possible to determine the approximate distance between genetic markers using cytogenetic mapping, but not the exact distance (number of base pairs).
  • This technique overcomes the limitation of genetic mapping and is not affected by increased or decreased recombination frequency.
  • An EST is a short STS that is identified with cDNA libraries, while SSLPs are obtained from known genetic markers and provide a link between genetic maps and physical maps.
  • Genetic maps provide the outline and physical maps provide the details.

• Introduction to Mendelian Inheritance

  • While working with pea plants, Gregor Mendel noticed that offspring were similar to their parent plants, which led him to some of the earliest theories about genetics.
  • Genetics is the study of heredity, or the passing of traits from parents to offspring.
  • Gregor Johann Mendel set the framework for genetics long before chromosomes or genes had been identified, at a time when meiosis was not well understood.
  • Today, the postulates put forth by Mendel form the basis of classical, or Mendelian, genetics.
  • Gregor Johann Mendel was a German-speaking Moravian scientist and Augustinian friar who gained posthumous fame as the founder of the modern science of genetics.

• Modern Applications of DNA

  • The acronym "DNA" has become synonymous with solving crimes, testing for paternity, identifying human remains, and genetic testing.
  • A genetically modified organism (GMO) is any organism whose genetic material has been altered using genetic engineering techniques.
  • Genetic modification involves the mutation, insertion, or deletion of genes.
  • Bacteria, plants, and animals have been genetically modified since the early 1970s for academic, medical, agricultural, and industrial purposes.
  • The GloFish is a patented and trademarked brand of genetically modified (GM) fluorescent fish.