Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species. It is distinguished from genetic variability, which illustrates the tendency of varied genetic characteristics.
Genetic diversity serves as a way for populations to adapt to changing environments. With more variety, it is more likely that some individuals in a population will have an allenable variation of the allele for the environment. Those people are more likely to survive to produce offspring that contain the allele. The population will continue for more generations because of the success of these individuals.
The academic field of population genetics includes several hypotheses and theories about genetic diversity. Neutral evolution theory proposes that diversity is the result of neutral substitution accumulation. Selection diversification is the hypothesis that two subpopulations of a species live in different environments that choose a different allele at a particular locus. This can happen, for example, if a species has a large range relative to the mobility of individuals within it. A frequency-dependent choice is the hypothesis that when alleles become more common, they become more vulnerable. This occurs in host-pathogen interactions, where the high frequency of defensive alleles among hosts means that it is more likely that the pathogen will spread if it is able to overcome the allele.
Video Genetic diversity
Species Diversity
A 2007 study conducted by the National Science Foundation found that genetic diversity and biodiversity (in terms of species diversity) depend on each other - that species diversity is necessary to maintain diversity among species, and vice versa. According to the lead researcher in this study, Richard Lankau, "If there is one type removed from the system, the cycle can be damaged, and society becomes dominated by one species." Genotype and phenotypic diversity have been found in all species at the protein, DNA, and organism levels; in nature, this diversity is not random, highly structured, and correlates with environmental variations and stress.
The interdependence between genetic diversity and species is very subtle. Changes in species diversity lead to changes in the environment, leading to adaptation of the remaining species. Changes in genetic diversity, such as loss of species, lead to loss of biodiversity. The loss of genetic diversity in domestic animal populations has also been studied and linked to market expansion and economic globalization.
Maps Genetic diversity
Evolution
Adaptation
Genetic diversity plays an important role in the survival and adaptability of a species. When a population changes, the population may have to adapt to survive; the ability of the population to adapt to a changing environment will determine their ability to overcome environmental challenges. The more genetic diversity a population has, the more likely the population will be able to adapt and survive. The susceptibility of a population to a particular type of disease can also increase with the decrease in genetic diversity, as a population may become unable to adapt to fight disease with limited immune possibilities.
For example, the inability of koalas to adapt to Chlamydia and koala retrovirus (KoRV) has been associated with a low genetic diversity of koalas. This low genetic diversity also has genetics of interest for the ability of koalas to adapt to climate change and human-caused environmental change in the future.
Variations in the population gene pool allow natural selection to act on the properties that allow the population to adapt to changing environments. Selection for or against properties may occur with environmental changes - resulting in an increase in genetic diversity (if new mutations are selected for and maintained) or decreased genetic diversity (if a detrimental allele is selected against).
Genetic Drift
Genes come in various forms, called alleles. An allele can be lost over time by random chance, called a genetic aberration. When the allele drifts into fixation, another allele in the same locus disappears (it drifts to zero), resulting in the loss of genetic diversity.
In small population sizes, mutations tend not to survive as they are more likely to be removed by drifting. Therefore, it is unlikely that new genetic diversity will be added. In small populations, inbreeding, or marriage between individuals with the same genetic makeup, are more likely to occur, thus perpetuating a more general allele to the point of fixation, thereby decreasing genetic diversity. Concerns about genetic diversity are therefore of great importance with large mammals because of their small population size and high levels of human-induced population effects. <16> Large populations are more likely to retain genetic material and thus generally have higher genetic diversity.
Genetic congestion can occur when the population reaches a small amount, and inequality and inbreeding lead to a decrease in genetic diversity. Even with an increase in population size, genetic diversity is often kept low if the entire species starts with a small population, because beneficial mutations (see below) are rare, and gene pools are limited by small initial populations. This is an important consideration in the field of conservation genetics, while working towards a rescued population or genetically healthy species.
Mutations
Random mutations consistently produce genetic variations. A mutation will increase the genetic diversity in the short term, since new genes are introduced into the gene pool. However, the persistence of this gene depends on deviations and selection (see above). Most new mutations have a neutral or negative effect on fitness, while some have a positive effect. Profitable mutations are more likely to persist and thus have a long-term positive effect on genetic diversity. The rate of mutation differs across the genome, and the larger population has a greater rate of mutation.
Gen Flow
Gene flow, often with migration, is the movement of genetic material (eg by pollen in the wind, or bird migration). Gene flow can introduce new alleles to a population. These alleles can be integrated into the population, thereby increasing the genetic diversity.
For example, insecticide-containing mutations appear in Anopheles gambiae African mosquitoes. The migration of several mosquitoes into mosquito populations Anopheles coluzziin produces beneficial gene resistance transfers from one species to another. Genetic diversity is increased in A. gambiae by mutation and in A. coluzziin by gene flow.
In agriculture
In plants
When humans begin farming, they use selective breeding to continue the desired properties of the plant while eliminating unwanted ones. Selective breeding leads to monoculture: all plant farms are almost genetically identical. Little or no genetic diversity makes crops particularly vulnerable to widespread diseases; Bacteria change and change constantly and when disease-causing bacteria change to attack certain genetic variations, it can easily remove large numbers of species. If the best genetic variation attacks the bacteria is that humans have been selectively bred for harvest, the whole plant will be erased.
The nineteenth century Irish Potato Famine is partly due to the lack of biodiversity. Because new potato plants do not come as a result of reproduction, but more than parent plant pieces, no genetic diversity is developed, and the whole plant is essentially an imitation of a potato, very vulnerable to epidemics. In the 1840s, most of Ireland's population relied on potatoes for food. They plant various types of "lumper" potatoes, which are susceptible to the oomycete that causes rot called Phytophthora infestans . Mushrooms destroy most of the potato plants, and make a million people die of starvation.
Genetic diversity in agriculture is not only related to disease, but also herbivores. Similarly, for the above example, monoculture farming selects for uniform properties throughout the plot. If the genotype is susceptible to certain herbivores, this can cause the loss of most plants. One way farmers overcome this is through inter-cropping. By planting unrelated planted or genetically distinct lines as a barrier between their chosen herbivores and host plants, farmers effectively reduce the ability of herbivores to spread throughout the plot.
In the farm
The genetic diversity of livestock species allows farming in different environments and with different purposes. It provides raw materials for selective breeding programs and allows livestock populations to adapt when environmental conditions change.
Livestock biodiversity can disappear as a result of breed extinctions and other forms of genetic erosion. In June 2014, among the 8,774 breeds recorded in the Domestic Animal Diversity Information System (DAD-IS), operated by the Food and Agriculture Organization of the United Nations (FAO), 17 percent were classified as at risk of extinction and 7 percent were extinct. There is now a Global Action Plan for Animal Genetic Resources developed under the Commission on Genetic Resources for Food and Agriculture in 2007, which provides the framework and guidelines for the management of animal genetic resources.
Awareness of the importance of maintaining the genetic resources of livestock has increased over time. FAO has published two reports on the status of the world's animal genetic resources for food and agriculture, which includes a detailed analysis of our global livestock diversity and the ability to manage and preserve it.
Viral Implications
High genetic diversity in viruses should be considered when designing vaccinations. High genetic diversity results in difficulty in designing targeted vaccines, and allows the virus to evolve rapidly to counter lethal vaccinations. For example, malaria vaccination is influenced by high levels of genetic diversity in protein antigens. In addition, genetic diversity of HIV-1 limits the use of current viral load and resistance testing.
Addressing low genetic diversity
Natural
The natural world has several ways to preserve or increase genetic diversity. Among the oceanic plankton, the virus helps in the process of genetic shift. Marine viruses, which infect plankton, carry the genes of organisms other than their own. When a virus containing a gene from one cell infects another cell, the genetic makeup of the last change. This constant shift in genetic makeup helps to maintain a healthy plankton population despite complex and unpredictable environmental changes.
Cheetahs are a threatened species. Low genetic diversity and poor sperm quality have made breeding and survival difficult for cheetahs. In addition, only about 5% of cheetahs survive to adulthood. However, it was recently discovered that a female cheetah can mate with more than one child per tiger. They undergo ovulation induction, which means that new eggs are produced every time a female partner. By mating with many males, the mother increases the genetic diversity in a single tiger cub.
Human Interventions
Efforts to increase the viability of a species by increasing genetic diversity are called genetic salvage. For example, eight panthers from Texas were introduced to the Florida tiger population, which declined and suffered from inbreeding depression. Such genetic variation increases and results in a significant increase in Florida Panther population growth. Creating or maintaining high genetic diversity is an important consideration in species rescue efforts, to ensure the longevity of a population.
Size
The genetic diversity of a population can be assessed by a few simple steps.
- Gene diversity is the proportion of polymorphic loci throughout the genome.
- Heterozygosity is the fraction of individuals in a heterozygous population for a particular locus.
- Alleles per locus are also used to indicate variability.
- Nucleotide diversity is the level of nucleotide polymorphism in a population, and is usually measured by molecular markers such as micro and minisatellite sequences, mitochondrial DNA, and single nucleotide polymorphisms (SNPs)./li>
In addition, stochastic simulation software is usually used to predict the future of a population given the size of such allele frequencies and population size.
Other diversity sizes
Alternatively, other types of diversity can be assessed for organisms:
- type diversity
- ecological diversity
- morphological diversity
- degeneration
There is a wide correlation between different types of diversity. For example, there is a close relationship between vertebrate taxonomy and ecological diversity.
See also
- Center of diversity
- Human genetic variation
- Human Variety Project
- International HapMap Project
References
External links
- Implementing the Global Action Plan on Animal Genetic Resources
- Domestic Animal Diversity Information System
- Genetic Resources Commission for Food and Agriculture
Source of the article : Wikipedia
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