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12

Your basic problem is indeed a fundamental misunderstanding of how DNA and by extension its evolution works. First of all, there is no such thing as "correct" or "error", there are only changes, some of them are better for the individual and some are worse. You also have a basic misunderstanding of the concept of information. An error does not decrease the ...


10

You question, I'm afraid, betrays a deep misunderstanding of evolution. Genetic mutation is just errors in replication. So it creates nothing. It simply degrades. This is patently false. The vast majority of mutations are "errors", in that they produce a less fit organism. But once in a while, a mutation will confer an advantage, rather than an ...


7

No, they are of course not there to cause allergies. It is thought (although not directly proven in human) that IgE is important to fight parasites and worms. They bind to antigens from the parasites, which leads to the secretion of histamines. This causes a local immune reaction (which also is a problem in allergies) which is helpful to fight the parasites. ...


6

Has anyone calculated or simulated how the adaptation for many different traits can happen simultaneously? There are a lots of studies on the subject but I don't fully understand what is your issue. So I'll try to give some words hoping that helps a bit but it is possible that I'll totally miss the point you want to make. The mutation rate in humans is ...


6

It's seems to me you forget something pretty important about evolution : it has nothing to do with improvement. All living organisms have the exact same time of evolution as they all derive from a common ancestor. They simply evolved through different paths, that's what explain the biodiversity we can observe today and no organism is better than others, not ...


5

Earwax, also called cerumen, is slightly acidic (1), with a pH of about 6, and acidic foods or substances taste sour. The composition of earwax, upon which its taste depends, is related to its functions. Earwax aids in cleaning and lubrication of the ear canal and has an antimicrobial effect. The antimicrobial effect is in part attributed to its acidity, ...


5

Short answer Yes that would work in the condition that the trait you select for (size) is heritable. Long answer The kind of selection you would apply is called truncated selection because you fix a limit in size (depends on your filter) under which individuals do not survive and above which individuals survive and reproduce equally. The response to ...


5

Toilets have always been a great place to think about biology, I agree $\ddot \smile$. In short, urine contains the waste from our blood while defecation is just the stuff that we haven't digested. Kidneys are the organs responsible for draining wastes (mostly nitrogen-containing, or nitrogenous, wastes) from our blood. You're correct that the loss of ...


4

Where does the information come from? From the environment, and the previous history of interactions in that environment. The process of evolution can be viewed as an undirected search for "good" solutions (i.e. those that better support replication) to problems presented by the environment. There is a large amount of information (in the information-theory ...


4

Background I'd like to start by saying that traits phenotypic (loosely speaking phenotypic mean morphological) traits evolve because their variance is correlated with some genetic variance. If most of the phenotypic variance is genetically coded, you'd expect that the trait will change through if different variant of the trait influence fitness (which is a ...


3

There is a substantial variation in some human traits: hair colour, eye colour, height, weight, skin colour, build etc. etc. HOWEVER there is also considerable variation within other species, to suggest otherwise is naive (though quite common). We often feel like there is more variation within our own species because we are more aware of the subtle ...


3

I don't believe you can produce a general function for this. It will depend on the exact gene and organism you are considering. From a molecular point of view, the vast majority of recessive mutations result from a change producing either a non-functional protein product or a truncated product that is cleaned up by the cell. We can reasonably assume that ...


3

To a good first approximation $\overline{\Delta f} = 0$. Where $\overline{\Delta f}$ is the mean change in fitness down to any point or indel mutation. The reasons for this are as follows: In the genome of higher organisms, most of the genome is non-functional ("junk") so most mutations will not have any effect regardless of the change made. A substantial ...


2

Some elements of response to your question. First, something about tRNA frequency. Even if there are six codons for a given amino acid, they are not equivalent because some will correspond to abundant tRNA, while others correspond to very minor tRNA. This has significant influence on the traduction speed, as the traduction will dramatically slow down on ...


2

I think this is a little like writing a book. The most common advice is for aspiring writers to write every day and write a decent amount. Evolution creates by testing everything against its fitness - its ability to survive and reproduce. If something is advantageous, it stays in the corpus of genes and genetic solutions to problems. If something is ...


2

What you say is true, but the answer as to how modern evolutionary theory understand this considers other ideas about living things which seem to allow so called 'neutral traits'. Neutral traits being those phenotypes which seem to have no particular relationship to fitness. Toungue rolling is an often mentioned example. Some folks argue that there is ...


2

The short answer is: Because of genetic drift. If a mutation does not influence the fitness in heterozygote individuals, then its frequency varies only through genetic drift while it reaches some high enough frequency. If by chance, the frequency of this new allele achieve a high enough level so that the homozygous for this allele given by $x^2$ where $x$ is ...


2

A Biologist's guide to mathematical modeling in evolution and ecology (Otto) is a very good book that is presented for people that have highschool level in mathematics (It makes a good review in linear algebra for example). It is highly accessible and in the meantime it goes pretty far as it ends up talking about the application of diffusion equation in ...


2

I think the main issue you have is in this paragraph: But if mutations are rare, it seems unlikely that many (thousands of) properties of organisms get improved in a single generation. You'd need to get very lucky to randomly improve all the genes responsible for it. There are two basic misconceptions there: Mutations are not rare. They're actually ...


2

It is understood that Evolution basically involves three elements. Natural selection, genetic mutation, and time. The problem for Evolution, is that none of those three elements are creative. They absolutely are creative in that they create something new. Mutation introduces random errors, some of which may never have existed before in that combination ...


2

Is this the exact text from the book? The left side seems to represent the probability for "No coalescence in $k$ lines in $t$ generations (i.e. the $Pr(k)^t$ term), and at least one coalescence among those lines in generation $t+1$ (the $1-Pr(k)$ term)" which is the same event as "First coalescence event in $k$ lines is exactly in generation ...


2

You may consider consulting the H2DB database. The database is quite new, so the number of heritability estimates is not very high at the moment (currently 225 estimates for human, 838 estimates in total), but it's a start. The database is described in a paper by Kaminuma et al.(2)


1

It is generally known that the smaller (or less complex) an organism is, the more "condensed" it's genome is. For example, bacteria (or some eukaryotes) have operons (http://en.wikipedia.org/wiki/Operon) or overlapping genes using different and they don't have introns, which alltogether saves a lot of space. There are many reasons for that. Available space ...


1

The basic idea is that mutations improving different traits can occur in different individuals, and then be brought together by recombination. So the frequency of recombination roughly sets the maximum rate at which the population can acquire good mutations. Nick Barton and I calculated it, and found that a population can gain about one good mutation per ...


1

This varies by the kind of animal or plant. I think one company would rarely do both. For plants Monsanto comes to mind. And Syngenta. I'm not sure for animals. For beef cattle in the US, this is done by individual ranchers (who may be corporations) that collectively share their genetic data creating a market which can predict the value of a bull. The ...


1

To derive it, first use that $E[x(1-x)]= E[x-x^2]=E[x]-E[x^2]$ and that $E[x^2]=\text{Var}[x]+E[x]^2$ to rewrite the left-hand side: $$E\left[x_{t+1}(1-x_{t+1})\right] = E\left[x_{t+1}\right](1-E\left[x_{t+1}\right])-\text{Var}\left[x_{t+1}\right].$$ The equation for $p_{ij}$ is just saying that $2Nx_{t+1}$ is binomially distributed with $2N$ trials with ...


1

The notation at this site resembles that in your question but preserves the $\frac{x_t}{2N}$ notation for probability of selecting an allele. $$E[\frac{x_{t+1}}{2N})(1 - \frac{x_{t+1}}{2N} )|x_t] = (\frac{x_{t}}{2N})(1 - \frac{x_{t}}{2N}) (1 - \frac{1}{2N}) $$ The expression $(\frac{x_{t}}{2N})(1 - \frac{x_{t}}{2N}) $ is the probability of heterozygosity ...


1

I think the key work here is 'evolve'. Overall GC/AT ratios change by mutations, whose rate is constant. The probability that given a mutation event that one base will be substituted by another one has been modeled in several ways where the probabilities of different mutations may or may not be the same. Overall the GC content will tend to close to 50%. ...


1

[This is purely speculative] Assumptions: impact on fitness is measured by survival chance impact is because of protein coding genes Probability of a mutation at position $i$ $P(m=i\ |\ g)$ where $g$ is the genome with its annotations. Probability that activity of some protein changes by X-fold given mutation at $i^{th}$ position(s) in the genome: ...


1

Not in general -- there can be linkage disequilibrium among the loci. For instance, say that there are two di-allelic loci, $A/a$ and $B/b$, and that the frequencies of the $A$ and $B$ alleles are both $1/2$ and that they have the same effect on the trait, with no dominance. If all haplotypes in the population are either $Ab$ or $aB$ (with no $AB$ or $ab$ ...



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