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75-586: In February 2020, electron microscope images of SARS-CoV-2 were collected at RML. Rocky Mountain Laboratories began as the Montana Board of Entomology Laboratory. It was opened in 1928 by the Montana State Board of Entomology to study Rocky Mountain spotted fever and the ticks, Dermacentor andersoni , that carry it. Local opposition to the "tick lab" was strong, as residents worried ticks would escape

150-425: A public health emergency of international concern from January 30, 2020, to May 5, 2023. SARS‑CoV‑2 is a positive-sense single-stranded RNA virus that is contagious in humans. SARS‑CoV‑2 is a strain of the species Betacoronavirus pandemicum (SARSr-CoV), as is SARS-CoV-1 , the virus that caused the 2002–2004 SARS outbreak . There are animal-borne coronavirus strains more closely related to SARS-CoV-2,

225-443: A decrease in genetic diversity (if a disadvantageous allele is selected against). Hence, genetic diversity plays an important role in the survival and adaptability of a species. The capability of the population to adapt to the changing environment will depend on the presence of the necessary genetic diversity. The more genetic diversity a population has, the more likelihood the population will be able to adapt and survive. Conversely,

300-491: A disease-causing bacterium changes to attack a specific genetic variation, it can easily wipe out vast quantities of the species. If the genetic variation that the bacterium is best at attacking happens to be that which humans have selectively bred to use for harvest, the entire crop will be wiped out. The nineteenth-century Great Famine in Ireland was caused in part by a lack of biodiversity. Since new potato plants do not come as

375-467: A family of viruses. By 12 January 2020, five genomes of SARS‑CoV‑2 had been isolated from Wuhan and reported by the Chinese Center for Disease Control and Prevention (CCDC) and other institutions; the number of genomes increased to 42 by 30 January 2020. A phylogenetic analysis of those samples showed they were "highly related with at most seven mutations relative to a common ancestor ", implying that

450-678: A membrane protein that regulates the renin–angiotensin system. During the initial outbreak in Wuhan , China, various names were used for the virus; some names used by different sources included "the coronavirus" or "Wuhan coronavirus". In January 2020, the World Health Organization (WHO) recommended "2019 novel coronavirus" (2019-nCoV) as the provisional name for the virus. This was in accordance with WHO's 2015 guidance against using geographical locations, animal species, or groups of people in disease and virus names. On 11 February 2020,

525-413: A mink euthanasia campaign rendering it virtually extinct. Each SARS-CoV-2 virion is 60–140 nanometres (2.4 × 10 –5.5 × 10  in) in diameter; its mass within the global human populace has been estimated as being between 0.1 and 10 kilograms. Like other coronaviruses, SARS-CoV-2 has four structural proteins, known as the S ( spike ), E ( envelope ), M ( membrane ), and N ( nucleocapsid ) proteins;

600-486: A new egg is produced every time a female mates. By mating with multiple males, the mother increases the genetic diversity within a single litter of cubs. Attempts to increase the viability of a species by increasing genetic diversity is called genetic rescue. For example, eight panthers from Texas were introduced to the Florida panther population, which was declining and suffering from inbreeding depression. Genetic variation

675-418: A particular locus. This may occur, for instance, if a species has a large range relative to the mobility of individuals within it. Frequency-dependent selection is the hypothesis that as alleles become more common, they become more vulnerable. This occurs in host–pathogen interactions , where a high frequency of a defensive allele among the host means that it is more likely that a pathogen will spread if it

750-421: A range of animals—such as cats, ferrets, hamsters, non-human primates, minks, tree shrews, raccoon dogs, fruit bats, and rabbits—that are susceptible and permissive to SARS-CoV-2 infection. Some institutions have advised that those infected with SARS‑CoV‑2 restrict their contact with animals. On 1   February 2020, the World Health Organization (WHO) indicated that "transmission from asymptomatic cases

825-500: A range of different objectives. It provides the raw material for selective breeding programmes and allows livestock populations to adapt as environmental conditions change. Livestock biodiversity can be lost as a result of breed extinctions and other forms of genetic erosion . As of June 2014, among the 8,774 breeds recorded in the Domestic Animal Diversity Information System ( DAD-IS ), operated by

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900-402: A rapid decline in genetic diversity may be highly susceptible to extinction. Variation in the populations gene pool allows natural selection to act upon traits that allow the population to adapt to changing environments. Selection for or against a trait can occur with changing environment – resulting in an increase in genetic diversity (if a new mutation is selected for and maintained) or

975-426: A rapid decrease in genetic diversity. Even with an increase in population size, the genetic diversity often continues to be low if the entire species began with a small population, since beneficial mutations (see below) are rare, and the gene pool is limited by the small starting population. This is an important consideration in the area of conservation genetics , when working toward a rescued population or species that

1050-440: A result of reproduction, but rather from pieces of the parent plant, no genetic diversity is developed, and the entire crop is essentially a clone of one potato, it is especially susceptible to an epidemic. In the 1840s, much of Ireland's population depended on potatoes for food. They planted namely the "lumper" variety of potato, which was susceptible to a rot-causing oomycete called Phytophthora infestans . The fungus destroyed

1125-430: A single linear RNA segment. Coronaviruses infect humans, other mammals, including livestock and companion animals, and avian species. Human coronaviruses are capable of causing illnesses ranging from the common cold to more severe diseases such as Middle East respiratory syndrome (MERS, fatality rate ~34%). SARS-CoV-2 is the seventh known coronavirus to infect people, after 229E , NL63 , OC43 , HKU1 , MERS-CoV , and

1200-412: A site. The furin cleavage site PRRAR↓ is highly similar to that of the feline coronavirus , an alphacoronavirus 1 strain. Viral genetic sequence data can provide critical information about whether viruses separated by time and space are likely to be epidemiologically linked. With a sufficient number of sequenced genomes , it is possible to reconstruct a phylogenetic tree of the mutation history of

1275-454: Is a strain of coronavirus that causes COVID-19 , the respiratory illness responsible for the COVID-19 pandemic . The virus previously had the provisional name 2019 novel coronavirus ( 2019-nCoV ), and has also been called human coronavirus 2019 ( HCoV-19 or hCoV-19 ). First identified in the city of Wuhan , Hubei, China, the World Health Organization designated the outbreak

1350-479: Is able to overcome that allele . A study conducted by the National Science Foundation in 2007 found that genetic diversity (within-species diversity) and biodiversity are dependent upon each other — i.e. that diversity within a species is necessary to maintain diversity among species, and vice versa. According to the lead researcher in the study, Dr. Richard Lankau, "If any one type is removed from

1425-477: Is another possible cause of infection. Preliminary research indicates that the virus may remain viable on plastic ( polypropylene ) and stainless steel ( AISI 304 ) for up to three days, but it does not survive on cardboard for more than one day or on copper for more than four hours. The virus is inactivated by soap, which destabilizes its lipid bilayer . Viral RNA has also been found in stool samples and semen from infected individuals. The degree to which

1500-425: Is approximately 30,000 bases in length, relatively long for a coronavirus—which in turn carry the largest genomes among all RNA families. Its genome consists nearly entirely of protein-coding sequences, a trait shared with other coronaviruses. A distinguishing feature of SARS‑CoV‑2 is its incorporation of a polybasic site cleaved by furin , which appears to be an important element enhancing its virulence. It

1575-413: Is genetically healthy. Random mutations consistently generate genetic variation . A mutation will increase genetic diversity in the short term, as a new gene is introduced to the gene pool. However, the persistence of this gene is dependent of drift and selection (see above). Most new mutations either have a neutral or negative effect on fitness, while some have a positive effect. A beneficial mutation

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1650-449: Is likely not a major driver of transmission". One meta-analysis found that 17% of infections are asymptomatic, and asymptomatic individuals were 42% less likely to transmit the virus. However, an epidemiological model of the beginning of the outbreak in China suggested that "pre-symptomatic shedding may be typical among documented infections" and that subclinical infections may have been

1725-680: Is likely to have occurred in late 2019. Epidemiological studies estimate that in the period between December 2019 and September 2020 each infection resulted in an average of 2.4–3.4 new infections when no members of the community were immune and no preventive measures were taken. However, some subsequent variants have become more infectious. The virus is airborne and primarily spreads between people through close contact and via aerosols and respiratory droplets that are exhaled when talking, breathing, or otherwise exhaling, as well as those produced from coughs and sneezes. It enters human cells by binding to angiotensin-converting enzyme 2 (ACE2),

1800-417: Is more likely to occur, thus perpetuating more common alleles to the point of fixation, thus decreasing genetic diversity. Concerns about genetic diversity are therefore especially important with large mammals due to their small population size and high levels of human-caused population effects. A genetic bottleneck can occur when a population goes through a period of low number of individuals, resulting in

1875-408: Is more likely to persist and thus have a long-term positive effect on genetic diversity. Mutation rates differ across the genome, and larger populations have greater mutation rates. In smaller populations a mutation is less likely to persist because it is more likely to be eliminated by drift. Gene flow , often by migration, is the movement of genetic material (for example by pollen in the wind, or

1950-564: Is most often measured indirectly. For example, heritability can be measured as h 2 = V A / V P {\displaystyle h^{2}=V_{A}/V_{P}} or adaptive population differentiation can be measured as Q S T = V G / ( V G + 2 V A ) {\displaystyle Q_{ST}=V_{G}/(V_{G}+2V_{A})} . It may be possible to identify adaptive genes through genome-wide association studies by analyzing genomic data at

2025-467: Is the protein responsible for allowing the virus to attach to and fuse with the membrane of a host cell; specifically, its S1 subunit catalyzes attachment, the S2 subunit fusion. Genetic diversity Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species. It ranges widely, from the number of species to differences within species , and can be correlated to

2100-707: The International Committee on Taxonomy of Viruses adopted the official name "severe acute respiratory syndrome coronavirus 2" (SARS‑CoV‑2). To avoid confusion with the disease SARS , the WHO sometimes refers to SARS‑CoV‑2 as "the COVID-19 virus" in public health communications and the name HCoV-19 was included in some research articles. Referring to COVID-19 as the "Wuhan virus" has been described as dangerous by WHO officials, and as xenophobic by many journalists and academics. Human-to-human transmission of SARS‑CoV‑2

2175-482: The United States Public Health Service used the laboratory to manufacture Yellow fever vaccine . When the human serum–base vaccine caused an outbreak of Hepatitis B that infected more than 350,000 U.S. soldiers, two researchers at the laboratory, Dr. Mason Hargett and Harry Burruss , developed an aqueous-base vaccine that combined distilled water with virus grown in chicken eggs. By the end of

2250-469: The index case ". The authors later published a correction that showed that shedding began earlier than first estimated, four to five days before symptoms appear. There is uncertainty about reinfection and long-term immunity. It is not known how common reinfection is, but reports have indicated that it is occurring with variable severity. The first reported case of reinfection was a 33-year-old man from Hong Kong who first tested positive on 26 March 2020,

2325-483: The nasal cavity is seemingly the dominant initial site of infection, with subsequent aspiration -mediated virus-seeding into the lungs in SARS‑CoV‑2 pathogenesis. They found that there was an infection gradient from high in proximal towards low in distal pulmonary epithelial cultures, with a focal infection in ciliated cells and type 2 pneumocytes in the airway and alveolar regions respectively. Studies have identified

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2400-596: The Food and Agriculture Organization of the United Nations ( FAO ), 17 percent were classified as being at risk of extinction and 7 percent already extinct. There is now a Global Plan of Action for Animal Genetic Resources that was developed under the auspices of the Commission on Genetic Resources for Food and Agriculture in 2007, that provides a framework and guidelines for the management of animal genetic resources. Awareness of

2475-492: The N protein holds the RNA genome, and the S, E, and M proteins together create the viral envelope . Coronavirus S proteins are glycoproteins and also type I membrane proteins (membranes containing a single transmembrane domain oriented on the extracellular side). They are divided into two functional parts (S1 and S2). In SARS-CoV-2, the spike protein, which has been imaged at the atomic level using cryogenic electron microscopy ,

2550-401: The SARS‑CoV‑2 genome (matches above 90 percent may sound high, but in genomic terms it is a wide evolutionary gap ). In addition, despite similarities in a few critical amino acids, pangolin virus samples exhibit poor binding to the human ACE2 receptor. SARS‑CoV‑2 belongs to the broad family of viruses known as coronaviruses . It is a positive-sense single-stranded RNA (+ssRNA) virus, with

2625-577: The amino acid sequence P RR A . This sequence is upstream of an arginine and serine which forms the S1/S2 cleavage site ( P RR A R ↓ S ) of the spike protein. Although such sites are a common naturally-occurring feature of other viruses within the Subfamily Orthocoronavirinae, it appears in few other viruses from the Beta-CoV genus, and it is unique among members of its subgenus for such

2700-428: The coronavirus RNA genome is catalyzed by an RNA-dependent RNA polymerase . During replication this polymerase may undergo template switching, a form of homologous recombination. This process which also generates genetic diversity appears to be an adaptation for coping with RNA genome damage. The natural world has several ways of preserving or increasing genetic diversity. Among oceanic plankton , viruses aid in

2775-405: The crop. One way farmers get around this is through inter-cropping . By planting rows of unrelated, or genetically distinct crops as barriers between herbivores and their preferred host plant, the farmer effectively reduces the ability of the herbivore to spread throughout the entire plot. The genetic diversity of livestock species permits animal husbandry in a range of environments and with

2850-418: The differences between what was then called 2019-nCoV and the virus from the 2003 SARS outbreak were insufficient to make them separate viral species . Therefore, they identified 2019-nCoV as a virus of Severe acute respiratory syndrome–related coronavirus . In July 2020, scientists reported that a more infectious SARS‑CoV‑2 variant with spike protein variant G614 has replaced D614 as the dominant form in

2925-620: The environment, leading to adaptation of the remaining species. Changes in genetic diversity, such as in loss of species, leads to a loss of biological diversity . Loss of genetic diversity in domestic animal populations has also been studied and attributed to the extension of markets and economic globalization . Neutral genetic diversity consists of genes that do not increase fitness and are not responsible for adaptability. Natural selection does not act on these neutral genes. Adaptive genetic diversity consists of genes that increase fitness and are responsible for adaptability to changes in

3000-400: The environment. Adaptive genes are responsible for ecological, morphological, and behavioral traits. Natural selection acts on adaptive genes which allows the organisms to evolve. The rate of evolution on adaptive genes is greater than on neutral genes due to the influence of selection. However, it has been difficult to identify alleles for adaptive genes and thus adaptive genetic diversity

3075-640: The first human infection occurred in November or December 2019. Examination of the topology of the phylogenetic tree at the start of the pandemic also found high similarities between human isolates. As of 21 August 2021, 3,422 SARS‑CoV‑2 genomes, belonging to 19 strains, sampled on all continents except Antarctica were publicly available. On 11 February 2020, the International Committee on Taxonomy of Viruses announced that according to existing rules that compute hierarchical relationships among coronaviruses based on five conserved sequences of nucleic acids,

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3150-543: The first infection, but the mechanisms that could account for this are not known. No natural reservoir for SARS-CoV-2 has been identified. Prior to the emergence of SARS-CoV-2 as a pathogen infecting humans, there had been two previous zoonosis -based coronavirus epidemics, those caused by SARS-CoV-1 and MERS-CoV . The first known infections from SARS‑CoV‑2 were discovered in Wuhan, China. The original source of viral transmission to humans remains unclear, as does whether

3225-512: The future. Large populations are more likely to maintain genetic material and thus generally have higher genetic diversity. Small populations are more likely to experience the loss of diversity over time by random chance, which is an example of genetic drift . When an allele (variant of a gene) drifts to fixation, the other allele at the same locus is lost, resulting in a loss in genetic diversity. In small population sizes, inbreeding , or mating between individuals with similar genetic makeup,

3300-758: The genetic shifting process. Ocean viruses, which infect the plankton, carry genes of other organisms in addition to their own. When a virus containing the genes of one cell infects another, the genetic makeup of the latter changes. This constant shift of genetic makeup helps to maintain a healthy population of plankton despite complex and unpredictable environmental changes. Cheetahs are a threatened species . Low genetic diversity and resulting poor sperm quality has made breeding and survivorship difficult for cheetahs. Moreover, only about 5% of cheetahs survive to adulthood. However, it has been recently discovered that female cheetahs can mate with more than one male per litter of cubs. They undergo induced ovulation, which means that

3375-425: The genus Arabidopsis , appear to have high adaptive potential despite suffering from low genetic diversity overall due to severe bottlenecks . Therefore species with low neutral genetic diversity may possess high adaptive genetic diversity, but since it is difficult to identify adaptive genes, a measurement of overall genetic diversity is important for planning conservation efforts and a species that has experienced

3450-616: The importance of maintaining animal genetic resources has increased over time. FAO has published two reports on the state of the world's animal genetic resources for food and agriculture , which cover detailed analyses of our global livestock diversity and ability to manage and conserve them. High genetic diversity in viruses must be considered when designing vaccinations. High genetic diversity results in difficulty in designing targeted vaccines, and allows for viruses to quickly evolve to resist vaccination lethality. For example, malaria vaccinations are impacted by high levels of genetic diversity in

3525-493: The laboratory and cause an outbreak in the community. To allay their fears, the original laboratory building featured a small moat around its perimeter. In 1932, after spotted fever was diagnosed in other states, the federal government bought the facility and renamed it Rocky Mountain Laboratory. The laboratory expanded, adding faculty to study zoonotic diseases including typhus , tularemia , and Q-fever . During World War II ,

3600-494: The migration of a bird). Gene flow can introduce novel alleles to a population. These alleles can be integrated into the population, thus increasing genetic diversity. For example, an insecticide -resistant mutation arose in Anopheles gambiae African mosquitoes. Migration of some A. gambiae mosquitoes to a population of Anopheles coluzziin mosquitoes resulted in a transfer of the beneficial resistance gene from one species to

3675-491: The most closely known relative being the BANAL-52 bat coronavirus. SARS-CoV-2 is of zoonotic origin; its close genetic similarity to bat coronaviruses suggests it emerged from such a bat-borne virus . Research is ongoing as to whether SARS‑CoV‑2 came directly from bats or indirectly through any intermediate hosts. The virus shows little genetic diversity , indicating that the spillover event introducing SARS‑CoV‑2 to humans

3750-612: The much larger clades . Several different clade nomenclatures have been proposed. Nextstrain divides the variants into five clades (19A, 19B, 20A, 20B, and 20C), while GISAID divides them into seven (L, O, V, S, G, GH, and GR). Several notable variants of SARS-CoV-2 emerged in late 2020. The World Health Organization has currently declared five variants of concern , which are as follows: Other notable variants include 6 other WHO-designated variants under investigation and Cluster 5 , which emerged among mink in Denmark and resulted in

3825-614: The natural reservoir of the virus that caused the 2002–2004 SARS outbreak has resulted in the discovery of many SARS-like bat coronaviruses , most originating in horseshoe bats . The closest match by far, published in Nature (journal) in February 2022, were viruses BANAL-52 (96.8% resemblance to SARS‑CoV‑2), BANAL-103 and BANAL-236, collected in three different species of bats in Feuang , Laos. An earlier source published in February 2020 identified

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3900-524: The original SARS-CoV . Like the SARS-related coronavirus implicated in the 2003 SARS outbreak, SARS‑CoV‑2 is a member of the subgenus Sarbecovirus ( beta-CoV lineage B). Coronaviruses undergo frequent recombination. The mechanism of recombination in unsegmented RNA viruses such as SARS-CoV-2 is generally by copy-choice replication, in which gene material switches from one RNA template molecule to another during replication. The SARS-CoV-2 RNA sequence

3975-492: The other. The genetic diversity was increased in A. gambiae by mutation and in A. coluzziin by gene flow. When humans initially started farming, they used selective breeding to pass on desirable traits of the crops while omitting the undesirable ones. Selective breeding leads to monocultures : entire farms of nearly genetically identical plants. Little to no genetic diversity makes crops extremely susceptible to widespread disease; bacteria morph and change constantly and when

4050-1807: The pandemic. Coronavirus genomes and subgenomes encode six open reading frames (ORFs). In October 2020, researchers discovered a possible overlapping gene named ORF3d , in the SARS‑CoV‑2 genome . It is unknown if the protein produced by ORF3d has any function, but it provokes a strong immune response. ORF3d has been identified before, in a variant of coronavirus that infects pangolins . A phylogenetic tree based on whole-genome sequences of SARS-CoV-2 and related coronaviruses is: ( Bat ) Rc-o319 , 81% to SARS-CoV-2, Rhinolophus cornutus , Iwate , Japan Bat SL-ZXC21 , 88% to SARS-CoV-2, Rhinolophus pusillus , Zhoushan , Zhejiang Bat SL-ZC45 , 88% to SARS-CoV-2, Rhinolophus pusillus , Zhoushan, Zhejiang Pangolin SARSr-CoV-GX, 85.3% to SARS-CoV-2, Manis javanica , smuggled from Southeast Asia Pangolin SARSr-CoV-GD, 90.1% to SARS-CoV-2, Manis javanica , smuggled from Southeast Asia Bat RshSTT182, 92.6% to SARS-CoV-2, Rhinolophus shameli , Steung Treng , Cambodia Bat RshSTT200, 92.6% to SARS-CoV-2, Rhinolophus shameli , Steung Treng, Cambodia (Bat) RacCS203 , 91.5% to SARS-CoV-2, Rhinolophus acuminatus , Chachoengsao , Thailand (Bat) RmYN02 , 93.3% to SARS-CoV-2, Rhinolophus malayanus , Mengla , Yunnan (Bat) RpYN06 , 94.4% to SARS-CoV-2, Rhinolophus pusillus , Xishuangbanna , Yunnan (Bat) RaTG13 , 96.1% to SARS-CoV-2, Rhinolophus affinis , Mojiang , Yunnan (Bat) BANAL-52 , 96.8% to SARS-CoV-2, Rhinolophus malayanus , Vientiane , Laos SARS-CoV-2 SARS-CoV-1 , 79% to SARS-CoV-2 There are many thousands of variants of SARS-CoV-2, which can be grouped into

4125-485: The population level. Identifying adaptive genetic diversity is important for conservation because the adaptive potential of a species may dictate whether it survives or becomes extinct , especially as the climate changes . This is magnified by a lack of understanding whether low neutral genetic diversity is correlated with high genetic drift and high mutation load . In a review of current research, Teixeira and Huber (2021), discovered some species, such as those in

4200-449: The protein antigens. In addition, HIV-1 genetic diversity limits the use of currently available viral load and resistance tests. Coronavirus populations have considerable evolutionary diversity due to mutation and homologous recombination . For example, the sequencing of 86 SARS-CoV-2 coronavirus samples obtained from infected patients revealed 93 mutations indicating the presence of considerable genetic diversity. Replication of

4275-570: The role of pangolins as an intermediate host was initially posited (a study published in July 2020 suggested that pangolins are an intermediate host of SARS‑CoV‑2-like coronaviruses ), subsequent studies have not substantiated their contribution to the spillover. Evidence against this hypothesis includes the fact that pangolin virus samples are too distant to SARS-CoV-2: isolates obtained from pangolins seized in Guangdong were only 92% identical in sequence to

4350-504: The source of a majority of infections. That may explain how out of 217 on board a cruise liner that docked at Montevideo , only 24 of 128 who tested positive for viral RNA showed symptoms. Similarly, a study of ninety-four patients hospitalized in January and February 2020 estimated patients began shedding virus two to three days before symptoms appear and that "a substantial proportion of transmission probably occurred before first symptoms in

4425-555: The source. For a virus recently acquired through a cross-species transmission, rapid evolution is expected. The mutation rate estimated from early cases of SARS-CoV-2 was of 6.54 × 10 per site per year. Coronaviruses in general have high genetic plasticity , but SARS-CoV-2's viral evolution is slowed by the RNA proofreading capability of its replication machinery. For comparison, the viral mutation rate in vivo of SARS-CoV-2 has been found to be lower than that of influenza. Research into

4500-537: The span of survival for a species. It is distinguished from genetic variability , which describes the tendency of genetic characteristics to vary. Genetic diversity serves as a way for populations to adapt to changing environments. With more variation, it is more likely that some individuals in a population will possess variations of alleles that are suited for the environment. Those individuals are more likely to survive to produce offspring bearing that allele. The population will continue for more generations because of

4575-416: The success of these individuals. The academic field of population genetics includes several hypotheses and theories regarding genetic diversity. The neutral theory of evolution proposes that diversity is the result of the accumulation of neutral substitutions. Diversifying selection is the hypothesis that two subpopulations of a species live in different environments that select for different alleles at

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4650-456: The system, the cycle can break down, and the community becomes dominated by a single species." Genotypic and phenotypic diversity have been found in all species at the protein , DNA , and organismal levels; in nature, this diversity is nonrandom, heavily structured, and correlated with environmental variation and stress . The interdependence between genetic and species diversity is delicate. Changes in species diversity lead to changes in

4725-399: The vast majority of the potato crop, and left one million people to starve to death. Genetic diversity in agriculture does not only relate to disease, but also herbivores . Similarly, to the above example, monoculture agriculture selects for traits that are uniform throughout the plot. If this genotype is susceptible to certain herbivores, this could result in the loss of a large portion of

4800-493: The virus RaTG13 , collected in bats in Mojiang , Yunnan, China to be the closest to SARS‑CoV‑2, with 96.1% resemblance. None of the above are its direct ancestor. Bats are considered the most likely natural reservoir of SARS‑CoV‑2. Differences between the bat coronavirus and SARS‑CoV‑2 suggest that humans may have been infected via an intermediate host; although the source of introduction into humans remains unknown. Although

4875-541: The virus became pathogenic before or after the spillover event . Because many of the early infectees were workers at the Huanan Seafood Market , it has been suggested that the virus might have originated from the market. However, other research indicates that visitors may have introduced the virus to the market, which then facilitated rapid expansion of the infections. A March 2021 WHO-convened report stated that human spillover via an intermediate animal host

4950-478: The virus is infectious during the incubation period is uncertain, but research has indicated that the pharynx reaches peak viral load approximately four days after infection or in the first week of symptoms and declines thereafter. The duration of SARS-CoV-2 RNA shedding is generally between 3 and 46 days after symptom onset. A study by a team of researchers from the University of North Carolina found that

5025-587: The virus may be airborne as well, with aerosols potentially being able to transmit the virus. During human-to-human transmission, between 200 and 800 infectious SARS‑CoV‑2 virions are thought to initiate a new infection. If confirmed, aerosol transmission has biosafety implications because a major concern associated with the risk of working with emerging viruses in the laboratory is the generation of aerosols from various laboratory activities which are not immediately recognizable and may affect other scientific personnel. Indirect contact via contaminated surfaces

5100-422: The virus. Another case study described a 25-year-old man from Nevada who tested positive for SARS‑CoV‑2 on 18 April 2020 and on 5 June 2020 (separated by two negative tests). Since genomic analyses showed significant genetic differences between the SARS‑CoV‑2 variant sampled on those two dates, the case study authors determined this was a reinfection. The man's second infection was symptomatically more severe than

5175-448: The vulnerability of a population to changes, such as climate change or novel diseases will increase with reduction in genetic diversity. For example, the inability of koalas to adapt to fight Chlamydia and the koala retrovirus (KoRV) has been linked to the koala's low genetic diversity. This low genetic diversity also has geneticists concerned for the koalas' ability to adapt to climate change and human-induced environmental changes in

5250-647: The war, the laboratory distributed more than 1 million doses of the improved yellow fever vaccine. In the post-war decades, the laboratory broadened its scope to study chlamydia trachomatis and transmissible spongiform encephalopathies including scrapie , mad cow disease , and chronic wasting disease . In 1982, Dr. Willy Burgdorfer discovered Borrelia burgdorferi , the tick-borne bacterium that causes Lyme disease . 46°14′15″N 114°09′35″W  /  46.23737°N 114.15985°W  / 46.23737; -114.15985 SARS-CoV-2 Severe acute respiratory syndrome coronavirus 2 ( SARS‑CoV‑2 )

5325-414: Was confirmed on 20 January 2020 during the COVID-19 pandemic . Transmission was initially assumed to occur primarily via respiratory droplets from coughs and sneezes within a range of about 1.8 metres (6 ft). Laser light scattering experiments suggest that speaking is an additional mode of transmission and a far-reaching one, indoors, with little air flow. Other studies have suggested that

5400-452: Was discharged on 15 April 2020 after two negative tests, and tested positive again on 15 August 2020 (142 days later), which was confirmed by whole-genome sequencing showing that the viral genomes between the episodes belong to different clades . The findings had the implications that herd immunity may not eliminate the virus if reinfection is not an uncommon occurrence and that vaccines may not be able to provide lifelong protection against

5475-490: Was suggested that the acquisition of the furin-cleavage site in the SARS-CoV-2 S protein was essential for zoonotic transfer to humans. The furin protease recognizes the canonical peptide sequence R X[ R / K ] R ↓X where the cleavage site is indicated by a down arrow and X is any amino acid . In SARS-CoV-2 the recognition site is formed by the incorporated 12 codon nucleotide sequence CCT CGG CGG GCA which corresponds to

5550-525: Was the most likely explanation, with direct spillover from bats next most likely. Introduction through the food supply chain and the Huanan Seafood Market was considered another possible, but less likely, explanation. An analysis in November 2021, however, said that the earliest-known case had been misidentified and that the preponderance of early cases linked to the Huanan Market argued for it being

5625-466: Was thus increased and resulted in a significant increase in population growth of the Florida Panther. Creating or maintaining high genetic diversity is an important consideration in species rescue efforts, in order to ensure the longevity of a population. Genetic diversity of a population can be assessed by some simple measures. Furthermore, stochastic simulation software is commonly used to predict

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