For many decades now researchers have referred to strains of any given organism as "wild type" when comparing to other strains or mutants of their creation. Yet, the true meaning of wild type continue to elude us. Phylogenetics gives us relationship context but is unable to define the term.
The organism as it was first isolated from nature or the most frequently encountered phenotype in natural populations. In a genetic experiment, it designates a strain from which mutants were derived.
I can see your logic. Allow me to contend that point. Would it be consider WT if you consider that acquired mutations favor it in some way and allows it to out compete ancestral forms?
@Angel: Yes, what is wild type today may not be wild type a hundred years from now, otherwise there will never be wild-type broccoli, rice, corn. wheat, etc. All our agricultural crops are essentially selected for specific traits.
Strangely enough, for biologists working with model organisms, "wild type" often means a strain under strict teleological maintenance by a stock center. In biological experiments, selecting the proper controls is fraught with peril.
--bks
wild type can be considered as ancestral plant or native plant. to be considered 'wild type', mutation of gene must not occur. As i know, only a handful of plants exist today can be said 'wild type' as most plants are hybrid or extinct. For example, for carrot, the wild type is purple carrot while hybrid is orange
Indeed I can see this for higher eukaryotes. However, for the bacterial domain this question is fairly tricky to answer.
Yes, true indeed. However, bacteria now are divided into 2: Kingdom Eubacteria and the Kingdom Archaebacteria. Kingdom Archaebacteria can be considered as 'wild types' as they can be found in extreme environment and the idea that ancestral organisms thrived in similar environment as well
On genetic level the most frequent allele within a gene population is defined as the wild type allele. This suggests, that an organism carrying all wild type allele genes should be defined as the wild type organism. The problem is, this is true within a species. And here I stop, because defining the term species is much more complicated compared to "wild type".
For genetic experiments, "wild type" normally means just the strain that you started to work with. The mutants you isolate or the derivatives that you construct by genetic manipulation always start with a defined clone. This is your wild type in a given genetic study regardless of its properties.
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Unlike culinary bananas, wild-type bananas have numerous large, hard seeds.
Wild type (or wildtype abbreviated wt) refers to the phenotype of the typical form of a species as it occurs in nature. Originally, the wild type was conceptualized as a product of the standard, "normal" allele at a locus, in contrast to that produced by a non-standard, "mutant" allele. It is now appreciated that most or all gene loci exist in a variety of allelic forms, which vary in frequency throughout the geographic range of a species, and that a uniform wild type does not exist. In general, however, the most prevalent allele[clarification needed] – e.g., the one with the highest gene frequency - is the one deemed as wild type.[1]
The concept of wild type is useful in some experimental organisms such as fruit flies Drosophila melanogaster, in which the standard phenotypes for features such as eye color or shape and wing form are known to be altered by particular gene mutations that produce distinctive phenotypes, such as "apricot" "bar eyes" or "vestigial wings". Wild-type alleles are indicated with a "+" superscript, for example B+ and vg+ for round eyes and full-size wings, respectively.
There is no such thing as a true wild type, it is an artificial definition to simplify laboratory experimentation.
Think about it from a human perspective, we are all different, which one of us is wild type? Organisms have an amazing degree of polymorphisms found in nature so the selection of wild type is usually arbitrary.
For most model organisms, one strain was selected at some time in the past, maybe for technical reasons or maybe just randomly, and selected as the "wild type" for that organism. This is true for bacteria, for yeast, for fruit fly, nematode, etc.
The organism as it was first isolated from nature or the most frequently encountered phenotype in natural populations. In a genetic experiment, it designates a strain from which mutants were derived.
In the case Vincent described, the wild type strain is the reference strain !
Thank you everyone for the feedback on this particular question. I must admit to you all that I posted the inquiry to see what the general feeling amongst us all, rather than lacking knowledge of its definition. For the record I subscribe strongly to Michael Benedick’s response in that wild type is not a tangible strain that truly exist for us to manipulate. If anything we could assign this term to a common ancestor of those species in which our interest lies. However, the term will remain a theoretical matter since those ancestral forms are long gone from the genomic composition of current species. I do understand however that we need a reference point to compare specially when investigating mutants and interesting variations across lineages of interest. As Benedick and some of you pointed out the term is use in the confines of laboratory experimentation and the wild type terminology satisfies the need solely as a descriptive term and not as a true definition of more archaic forms of a species. This of course is my opinion.
To Manech Kumar:
I appreciate your answer! However, let me present some clarifications if I may. Yes there are actually three define Domains in the most current three of life. Bacteria, Archaea and Eukaryota. Bacteria have their own separate domain while Archaea is considered to be a split from a common ancestral form of the Eukaryota. I must underline that Archaea is recognized as a separate domain all together but is does not share “close relatives” (I’m using this term loosely) with bacteria. Now you would be surprise to know that Archaea are not only extremophiles but rather can be found in a broad variety of ecosystems. Say for example, the human gut, soils, etc... One could argue that these organisms may posses ancestral forms of specific genes or group of genes but the argument regarding their been wild type has not be adequately supported.
As Angel Rivera's statement regarding my comment, it is true that the evidence and studies of Archeaa to be classified as wild type is lacking. However, I feel it is an interesting area of study to be carried out. As Archea have similar traits and genes, I think it's worth a shot. What the others think?
A wild type organism is one which possess all the enzymes for it's metabolic activities whereas a an auxotrophic bacterium needs a particular metabolite to be added externally.This can be exemplified as- a wild bacterium can synthesize all it's proteins and enzymes by a simple carbon source like glucose and a nitrogen source like ammonium sulphate whereas an auxotroph needs in addition to this growth factors like vitamins, amino acids or nucleotides.
In response to Manesh, I don't believe one should equate wild type with ancestral organism or last common ancestor, those are two different concepts. For example, I don't think any one of us would be able to select a wild type human (which one of us is wild type? Jim Watson??), would it be a modern human, an ancestral humanoid, a primate, or by your definition it could be an archeae. Nor do I actually think there is evidence that archeae are ancestors to the eubacteria (or vice verse).
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