107

At the moment, there is very little scientific literature about this, but I found two papers that address the problem and are fairly easy to understand. You can find them in the references. Reference 1 is probably the most interesting and is the basis for this answer. Edit: It is also interesting to read reference 2 on the origin of SARS-CoV-2; the article ...


54

It doesn't. Viruses don't "know" anything. Mutations occur at random. Most of them don't do anything, or have a slight negative effect on the ability of the virus to infect and reproduce. However, there are billions and billions of viruses. Once in a while a random mutation will offer a significant advantage like immunity to an anti-viral drug. The viruses ...


42

This is a poly(A) tail, which is a feature found in the majority of eukaryotic RNAs (especially mRNA) and is also not uncommon in RNA viruses (which essentially mimic endogenous mRNA for their own replication). As with mRNA, this poly(A) tail in coronaviruses is bound by poly(A) binding protein in the cytoplasm [1], which is involved in translation ...


33

It is highly unlikely that there exist any protein that is made from completely identical nucleotide sequences across the entire human population. There will certainly be regions within a gene that are highly conserved, but there is little evolutionary pressure to conserve an entire gene's nucleotide sequence across the population. This is in part due to ...


22

Humans have many variants There is variation. The project I use to help understand this natural variation is gnomAD. Using VarMap and a slightly out of date gnomAD file, I counted 16007805 protein-coding variants across the human genome. This number will only go up over time. Indeed, the 1000 Genome project found that on average each person has between 250-...


21

If you need more [counter]evidence, there's a newer paper "The proximal origin of SARS-CoV-2" by Andersen et al. (March, 17) that touches on the same topic. The paper brings up two reasons why SARS-CoV-2 is not "made in a lab". The first is the (relative) [in]efficiency of its spike protein; the second is somewhat more complex to explain ...


12

This is molecular evolution and is completely undirected. Mutations happen all the time, most of them disappear without anyone noticing, since they have no evolutionary advantage to permeate. This is different when you treat the cells and put them under an evolutionary pressure. Under this conditions, mutations which affect the mechanism of the drug (as ...


11

A quick search gives this same question in this Reddit post. Apparently, there is not yet an existing example of such dominance of three alleles on one another. That said, if you're interested in rock-paper-scissor patterns in nature, then you will be interested in the side-blotched lizard. It has three genetically encoded male "sexes", that also ...


8

While @CalendarJ comments "Yep!" above, a quick search suggests that experimental hyperoxia typically only increases insect body sizes slightly. Everything below is from VandenBrooks et al. 2012 (of course there could be other sources that contradict this!) A few beetles have been reported to reach larger sizes when reared in hyperoxia, but most of the ...


8

At the whole-gene level, there is likely no absolute conservation of any human protein-coding gene at the population level, though there might be complete conservation between individuals. Keep in mind that most human genes are on the order of tens of thousands of base pairs long, and only a portion of that length encodes functional motifs. There are, ...


8

How many generations are required for a specific neutral mutation to reach fixation? Kimura and Ohta (1968) showed that the expected time for a neutral allele to reach fixation is $$\bar t(p_0)=-4N\left(\frac{1-p_0}{p_0}\right)\ln(1-p_0),$$ where $p_0$ is the initial frequency and $N$ is the population size. The model assumes a Wright-Fisher population (...


8

Even a male cell can count the number of X chromosomes. (Lee et al. 1996; Cell 86: 83-84) When X inactivation is getting started the two chromosomes "kiss" - a process that lasts for a couple of hours (first shown by Jeannie Lee in 1996). The physical contact between two X chromosomes is over a small fraction of the chromosome but it's essential for ...


7

In humans, endogenous retroviruses (HERVs) comprise a substantial fraction of the genome, as much as 8%. While many historical viral incorporation events into the primate genome were likely neutral or detrimental (and therefore selected against), some were co-opted and are now functional elements in humans. An example: human syncytin is the envelope gene ...


7

Tarrare Tarrare was a showman who was renowned for his insatiable appetite including eating cats, dogs, and snakes sometimes raw. He is also said to have eaten many inedible items. At the time, he was alleged to have committed cannibalism of a 14-month-old baby and was caught in the act of cannibalising cadavers by hospital staff. He was given away as a ...


7

Summary: They Don't. Long explanation: Mutations happen at random. A series of factors can lead to the perceived notion that the mutation was intentional. The mutation can be harmful, beneficial, or neutral. Harmful: We don't see the harmful mutations as these individuals don't proliferate. The mutant individual just dies off without passing their ...


6

This can be a result of a somatic mutation, especially if the other flowers on the same plant don't have the same color pattern. Somatic mutations are not inherited for parent organisms but occur spontaneously in one of the cells in the body. If that cell then proliferates all of its descendants will have the mutation and new phenotype associated with it. ...


6

Good question--I think the first point to address is "a means to an end" seems to imply willful action. That is, evolution (according to Ridley) would be a conscious effort by a species to optimize the gene pool for survival of future generations; a rationalization for each species to mutate and diverge. This is not the case, for a couple of reasons. First, ...


6

I'll give here a simple, non-technical answer because I'm assuming you don't need to actually perform an analysis of ancestry. So, detecting ancestry is a non-trivial task. Given your genome sequence, you would need to compare some "informative" regions of the genome with the homologous sequences of some population (say, of a database with other genomes). ...


6

From your own PlosOne link comes proof that the selection pressure was very weak: "Most locations (59%, n = 37) were sampled in only one year, 20 locations in two years, five locations in three years, and one in four years, yielding in total 96 unique location-year combinations of measurements of seasonal total flying insect biomass." "We collected in total ...


6

De novo mutations can be inherited if they occur in the germline cells, those responsible for making the sperm or the egg. If you have a de novo mutation in a blood cell or a skin cell, this doesn't pass on to the next generation. But when you test the blood for mutations, it can also mean that the same mutation is present in the germline! However, if the ...


6

It would appear that the current policy at GenBank is to represent all genomic sequences as DNA, even though this is not made explicit in any of the easily retrievable documentation on their website or in their publications. The way in which one determines the nature of the genome is from the first (LOCUS) line in the report, which, in the case of SARS-CoV-2 ...


5

In certain species of parasitic wasp, contained within the wasp genome is the genome for a so-called "polydnavirus". The female wasp somehow creates instances of these polydnaviruses inside its ovaries. When the wasp injects an egg into a member of the host species (likely a caterpillar), several instances of the polydnavirus are also injected along with it....


5

Short answer: You need to buy some more, but you need the sequence also for ordering. Long answer: The Taq polymerase needs a piece of DNA (or RNA) to prime the reaction and be able to enlarge the DNA chain, this is why we use primers in the first place (also to ensure reaction specificity to the region we want to amplify). To enable the reaction you would ...


5

Molecular mechanisms of incomplete dominance (a.k.a. partial- or semi-dominance) vary. As an example, let's look at snapdragons and morning glories, two flowering plants that both exhibit incomplete dominance relative to flower pigmentation. Snapdragons (Antirrhinum majus) have multiple alleles at the nivea locus. The wild-type nivea transcript (niv+) ...


5

The cells differentiation during post fertilization period is govern by a set of regulatory genes called Homeotic genes.These are genes that "select" the identity of entire segments or structures in the bodies of developing organisms. These gene encodes a transcription factor that is expressed in a specific region of the organism starting in its early ...


5

Context is everything. Lets start by working back to front. larvae eat the tarantula organs in a specific sequence to keep it alive as long as possible. Most of the time if the larva eat the organs in the wrong order they don't die, they just end up with less food. It is pretty easy to see how this could evolve to be better, larva that eat in the ...


5

Many invertebrates possess myelin. It is a misconception that invertebrates lack myelin. The world speed record for a traveling bioelectric signal is held by the myelinated axons in the abdomen of the Penaeus shrimp! Please take a look at this website or this review to find a highly recommended comprehensive website about invertebrate myelin from about a ...


5

Yes, the internal exons are those that aren't at the ends, which are often referred to as terminal exons1. However, exons are sequences of nucleotides that are incorporated into the mature mRNA — i.e. they don't have to be (entirely) protein coding. It is probably simplest to think of exons as being the transcribed regions that are not introns — i.e. ...


5

If you are referring to the massive death toll among native Americans due to the epidemic disease outbreaks after first contact with European settlers, then the answer is rather straightforward (Science magazine News, 2016): The immune system is a complex structure, built over a person’s life in response to environmental conditions. Antibodies, proteins ...


5

A conclusive proof of CoV2's artificial origin would be finding lab records or samples dated before the epidemic, or finding an obvious unique marker sequence in the cDNA. To date there is no such conclusive proof. All other "proofs" I have seen are just hypotheses, and they all can be explained by natural processes too. In fact, if your opponents refuses ...


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