genetic diversity

Examples of genetic diversity in the following topics:

• Types of Biodiversity

  • Genetic diversity, ecosystem diversity, and human-derived diversity are measures of biodiversity that currently define life on earth.
  • Genetic diversity is one of those alternate concepts.
  • Genetic diversity or variation is the raw material for adaptation in a species.
  • A genus with very different types of species will have more genetic diversity than a genus with species that look alike and have similar ecologies.
  • Genetic diversity can be measured as chemical diversity in that different species produce a variety of chemicals in their cells, both the proteins as well as the products and by-products of metabolism.

• 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.
  • Because wild cheetahs are threatened, their species has a very low genetic diversity.
  • This low genetic diversity means they are often susceptible to disease and often pass on lethal recessive mutations; only about 5% of cheetahs survive to adulthood.

• Pollination and Fertilization

  • Plants can transfer pollen through self-pollination; however, the preferred method is cross-pollination, which maintains genetic diversity.
  • Genetic diversity is, therefore, required so that in changing environmental or stress conditions, some of the progeny can survive.
  • Self-pollination leads to the production of plants with less genetic diversity since genetic material from the same plant is used to form gametes and, eventually, the zygote.
  • In contrast, cross-pollination leads to greater genetic diversity because the male and female gametophytes are derived from different plants.
  • Because cross-pollination allows for more genetic diversity, plants have developed many ways to avoid self-pollination.

• Advantages and Disadvantages of Sexual Reproduction

  • The genetic diversity of sexual reproduction, observed in most eukaryotes, is thought to give species better chances of survival.
  • During sexual reproduction, the genetic material of two individuals is combined to produce genetically-diverse offspring that differ from their parents.
  • The genetic diversity of sexually-produced offspring is thought to give species a better chance of surviving in an unpredictable or changing environment.
  • On the surface, creating offspring that are genetic clones of the parent appears to be a better system.
  • No single species progresses too far ahead because genetic variation among the progeny of sexual reproduction provides all species with a mechanism to improve rapidly.

• Agricultural Diversity

  • Maintaining genetic biodiversity of wild species of our crops that are related to domesticated species ensures our continued food supply.
  • This crop diversity matched the cultural diversity of highly-subdivided populations of humans.
  • Potatoes are only one example of human-generated diversity.
  • The potato demonstrates a well-known example of the risks of low crop diversity.
  • Maintaining the genetic diversity of wild species related to domesticated species ensures our continued food supply.

• Prokaryotic Reproduction

  • Prokaryotes reproduce asexually by binary fission; they can also exchange genetic material by transformation, transduction, and conjugation.
  • Binary fission does not provide an opportunity for genetic recombination or genetic diversity, but prokaryotes can share genes by three other mechanisms .
  • Archaea are not affected by bacteriophages, but instead have their own viruses that translocate genetic material from one individual to another.
  • This short generation time, coupled with mechanisms of genetic recombination and high rates of mutation, result in the rapid evolution of prokaryotes, allowing them to respond to environmental changes (such as the introduction of an antibiotic) very rapidly.

• Processes and Patterns of Evolution

  • Natural selection can only occur in the presence of genetic variation; environmental conditions determine which traits are selected.
  • Genetic diversity within a population comes from two main mechanisms: mutation and sexual reproduction.
  • The genetic changes caused by mutation can have one of three outcomes:
  • Sexual reproduction also leads to genetic diversity: when two parents reproduce, unique combinations of alleles assemble to produce the unique genotypes and thus phenotypes in each of the offspring.
  • When two species evolve in diverse directions from a common point, it is called divergent evolution.

• The Diversity of Life

  • The diversity of life can be classified within the three major domains (Bacteria, Eukarya and Archaea) using phylogenetic trees.
  • The fact that biology, as a science, has such a broad scope has to do with the tremendous diversity of life on Earth.
  • The source of this diversity is evolution, the process of gradual change during which new species arise from older species.
  • To construct his tree, Woese used genetic relationships rather than similarities based on morphology (shape).
  • Woese's approach was revolutionary because comparisons of physical features are insufficient to differentiate between the prokaryotes that appear fairly similar in spite of their tremendous biochemical diversity and genetic variability.

• Defining Population Evolution

  • Genetic variation in a population is determined by mutations, natural selection, genetic drift, genetic hitchhiking, and gene flow.
  • Millions of years of evolutionary pressure caused some organisms to died while others survived, leaving earth with the diverse life forms we have today.
  • Within this diversity is unity; for example, all organisms are composed of cells and use DNA.
  • Five forces can cause genetic variation and evolution in a population: mutations, natural selection, genetic drift, genetic hitchhiking, and gene flow.
  • This diversity results from evolution.

• Gene Flow and Mutation

  • A population's genetic variation changes as individuals migrate into or out of a population and when mutations introduce new alleles.
  • Even a population that may initially appear to be stable, such as a pride of lions, can receive new genetic variation as developing males leave their mothers to form new prides with genetically-unrelated females.
  • Maintained gene flow between two populations can also lead to a combination of the two gene pools, reducing the genetic variation between the two groups.
  • Mutations are changes to an organism's DNA and are an important driver of diversity in populations.
  • This mutation has introduce a new allele into the population that increases genetic variation and may be passed on to the next generation.