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. Genetic variations are the differences in DNA segments or genes between individuals and each variation of a gene is called an allele.
For example, a population with many different alleles at a single chromosome locus has a high amount of genetic variation. Genetic variation is essential for natural selection because natural selection can only increase or decrease frequency of alleles that already exist in the population. The last three of these factors reshuffle alleles within a population, giving offspring combinations which differ from their parents and from others.
This process is called natural selection , and it is the main force that drives evolution. The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit.
The Rights Holder for media is the person or group credited. Tyson Brown, National Geographic Society. National Geographic Society. For information on user permissions, please read our Terms of Service. If you have questions about how to cite anything on our website in your project or classroom presentation, please contact your teacher. They will best know the preferred format. When you reach out to them, you will need the page title, URL, and the date you accessed the resource.
If a media asset is downloadable, a download button appears in the corner of the media viewer. If no button appears, you cannot download or save the media. Text on this page is printable and can be used according to our Terms of Service.
Any interactives on this page can only be played while you are visiting our website. You cannot download interactives. Credit: Katrina Liebich, U. Fish and Wildlife Service. Public domain. Genetic diversity and the portfolio effect can help buffer species against global change.
Take Pacific salmon as one example. Salmon have a wide range of life history strategies, perhaps most evident in the variation in spawning migration timing. Evolutionarily, different spawning runs arose because in certain years environmental conditions favored the success of offspring spawned at certain times. The stability of salmon abundances in southeast Alaska is often attributed to this high level of diversity.
With climate change, certain salmon life history strategies are frequently more favorable. Indeed, there is already genetic evidence of long-term changes in migration timing of adult salmon in the region see Kovach et al.
The greater the genetic diversity, the greater the opportunity for resiliency to future climate change. When it comes to fish conservation in an era of global change, genetic diversity is like that diversified financial portfolio. If you bet everything on one strain, you could end up with another potato famine.
It strengthens the ability of species and populations to resist diseases, pests, changes in climate and other stresses. Gene variations underpin their capacity to evolve and their flexibility to adapt. One way to better understand the importance of genetic diversity is to consider what happens when it is severely reduced.
The FAO has warned that declining genetic diversity in food and agriculture makes food crops and livestock more susceptible to disease and farmers more vulnerable to crop failure.
0コメント