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Note that Masatoshi Nei seems to be editing this article, adding references to his own work, and statements in his typically opinionated style (e.g., the one about Nei not thinking that codon use biases are important). I have no standing to complain, because I'm also a scientist associated with mutationism. I started editing this article years ago because it was so flagrantly bad. Eventually I began to realize that there was an objectivity and balance issue. The version of the article is clearly not well balanced in the sense that it presents a minority view sympathetically, without other points of view.
It is not entirely clear how to present this material consistent with wikipedia guidelines on objectivity and weight ( /info/en/?search=Wikipedia:Neutral_point_of_view#Due_and_undue_weight). I think if you asked 100 evolutionary biologists about "mutationism", most would identify it as a dead theory that denies selection and claims that evolution took place by dramatic mutations alone. They would say that it was disproved by population genetics, or by experimental breeding, or by Fisher's 1918 paper. The problem is that, if we are talking about historical mutationism, we should not rely on scientists, but on historians of science. The first generation of historians of evolution were strongly influenced by Mayr and his neo-Darwinian narrative, and seem to take a view much like the scientists, but their view has been under revision for quite a number of years, e.g., by Roll-Hansen, or by Gayon. [1] Provine [2] seems positively bitter about being misled by Mayr, et al. Actually Stoltzfus & Cable [3] argue that a close reading of Provine 1971 subverts his neo-Darwinian narrative and lends support to the view that contemporary evolutionary thinking is more like the thinking of early geneticists than it is like the Modern Synthesis.
As to the idea of contemporary mutationism, this is also unclear. I assume that most contemporary scientists are not aware of such a thing. Contemporary scientists exposed to Nei's writing may interpret his view similarly as a neutralist position that denies selection (e.g., [4]).
One way to get a sense of how contemporary scientists are responding to the notion of mutationism would be to look at reviews of Nei's book published in evolution trade journals by Wagner
[5] , Wright
Cite error: A <ref>
tag is missing the closing </ref>
(see the
help page). and others. There is also Gardner's piece entitled "Darwinism, not mutationism, explains the design of organisms",
[6] which is a review of Shapiro's book. This is odd because I don't think Shapiro actually refers to his own view as mutationism.
Dabs (
talk)
13:37, 18 July 2014 (UTC)
References
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I have updated the claim by Singer and Ames that a high G+C content could be selectively advantageous with a new reference to Palmeira et al. (2006) Jean R. Lobry 20:05, 3 January 2007 (UTC)
I can't find an answer to this question, and thought I would post it here: How do chromosome numbers change? Say a population of a given species, all of which share the same chromosome number, is isolated from the main population. Time goes by. Now the chromosome numbers are different in the two populations. Does that happen? If so, how? By what mechanisms? -- Serge 23:48, 6 December 2005 (UTC)
Short answer; Polyploidy. There's a very good book on the subject of genome evolution (including the evolution of chromosome number); The Evolution of the Genome by T. Ryan Gregory. You can google Polyploidy I'm pretty sure you'll find plenty of informations on the subject, mostly for plants. -- PhDP 07:03, 24 January 2006 (UTC)
I removed the following sentence:
It was also demonstrated that levels of mutation necessary to cause significant evolution were not present in the environment and would cause sterility; e.g., in fruit flies.
This sentence does not make sense and does not make reference to any recognizable facts. It refers to "levels of mutation . . . present in the environment", but mutation is not present in the environment, it is a process within organisms. By referring to sterility and fruit flies, the statement makes it sound like it is based on some specific experimental result. If so, what is the result? What is the reference?
Here you are referring to levels of radiation to which the flies are exposed, but the disputed statement refers nonsensically to "levels of mutation . . . in the environment". As I said, mutation is not "in the environment". It is an internal process. Mutation is not the same as damage induced by radiation, oxidation, etc: damage is not heritable, but mutations (by definition) are heritable changes. For instance, a TT photodimer is damage, not a mutation; a broken strand is not heritable, but if error-prone repair of the strand introduces nucleotide changes, this represents a mutation.
But just putting the process of mutation back inside the organisms where it belongs would not fix the flawed logic. What principle of mutationism conflicts with the observation that levels of radiation sufficient to produce artificially high levels of mutation (levels that you admit are unnatural) cause sterility in flies? I see no contradiction. Neither apparently did Thomas Hunt Morgan, the mutationist and founder of genetics whom you cite as a source.
This was such a mess, and overlapped so thoroughly with Saltation, that I've gone ahead and boldly merged the materials, and am now rewriting the article to cover the history. Not at all sure we need so much on historiography; and many rough edges remain to be smoothed off, but I hope people will be happy with the progress. Chiswick Chap ( talk) 09:08, 9 May 2017 (UTC)
AFAIK saltationism is opposed to gradualism (not "phyletic gradualism", which opposes punctuated equilibrium, both almost unrelated). Meaning that it allows for or affirms a greater role for mutations causing a more drastic phenotypic difference, as opposed evolution being restricted to gradual variation, the sort of mundane additive variation that accounts for the bulk of ordinary variation in living populations. For concrete but hypothetical examples, in the ancestors of whales, mutations that abort completely or much more dramatically the size of the hind legs/"fins", rather than the ordinary minute variation in size; for eyeless animals, mutations that simply abort the development of the eye (or even one eye, as may be the case with the Mexican tetra), versus genes for progressively more minute but normal eyes, over generations, until they finally reach phenotypic nonexistence. "Freaks", as opposed to "normals". And that is regardless of the "size" or whatever genetic aspect of the mutation at the DNA level -- DNA wasn't even known then. And even "mutationism" doesn't refer to "size" of mutations at the genetic level, but is rather about mutation as a "driving force" alongside selection, rather than just providing the "raw material". That is, if some mutations are recurring enough, they will add to the genetic frequencies of such recurring alleles, at least against neutral variation, and possibly even against some negative selection (maladaptive alleles aren't always completely eliminated, and can even be maintained or increase in frequency if they provide some compensatory advantage, such as sickle cell anemia versus malaria), with the end result possibly coupling alleles of other genes to cope with a recurring maladaptive variation. I can't provide references for such definitions right now, but if I'm not mistaken, this series of articles at the Sandwalk blog will corroborate at least the mutationism "versus" selectionism aspect, mutation as a driver of genetic frequencies. — Preceding unsigned comment added by 189.18.92.181 ( talk) 19:56, 25 June 2017 (UTC)
GA toolbox |
---|
Reviewing |
Reviewer: Dunkleosteus77 ( talk · contribs) 22:09, 10 December 2017 (UTC)
![]() | Mutationism has been listed as one of the
Natural sciences good articles under the
good article criteria. If you can improve it further,
please do so. If it no longer meets these criteria, you can
reassess it. Review: December 16, 2017. ( Reviewed version). |
![]() | This article is rated GA-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | |||||||||||||||||||||||||||||||||
|
Note that Masatoshi Nei seems to be editing this article, adding references to his own work, and statements in his typically opinionated style (e.g., the one about Nei not thinking that codon use biases are important). I have no standing to complain, because I'm also a scientist associated with mutationism. I started editing this article years ago because it was so flagrantly bad. Eventually I began to realize that there was an objectivity and balance issue. The version of the article is clearly not well balanced in the sense that it presents a minority view sympathetically, without other points of view.
It is not entirely clear how to present this material consistent with wikipedia guidelines on objectivity and weight ( /info/en/?search=Wikipedia:Neutral_point_of_view#Due_and_undue_weight). I think if you asked 100 evolutionary biologists about "mutationism", most would identify it as a dead theory that denies selection and claims that evolution took place by dramatic mutations alone. They would say that it was disproved by population genetics, or by experimental breeding, or by Fisher's 1918 paper. The problem is that, if we are talking about historical mutationism, we should not rely on scientists, but on historians of science. The first generation of historians of evolution were strongly influenced by Mayr and his neo-Darwinian narrative, and seem to take a view much like the scientists, but their view has been under revision for quite a number of years, e.g., by Roll-Hansen, or by Gayon. [1] Provine [2] seems positively bitter about being misled by Mayr, et al. Actually Stoltzfus & Cable [3] argue that a close reading of Provine 1971 subverts his neo-Darwinian narrative and lends support to the view that contemporary evolutionary thinking is more like the thinking of early geneticists than it is like the Modern Synthesis.
As to the idea of contemporary mutationism, this is also unclear. I assume that most contemporary scientists are not aware of such a thing. Contemporary scientists exposed to Nei's writing may interpret his view similarly as a neutralist position that denies selection (e.g., [4]).
One way to get a sense of how contemporary scientists are responding to the notion of mutationism would be to look at reviews of Nei's book published in evolution trade journals by Wagner
[5] , Wright
Cite error: A <ref>
tag is missing the closing </ref>
(see the
help page). and others. There is also Gardner's piece entitled "Darwinism, not mutationism, explains the design of organisms",
[6] which is a review of Shapiro's book. This is odd because I don't think Shapiro actually refers to his own view as mutationism.
Dabs (
talk)
13:37, 18 July 2014 (UTC)
References
{{
cite book}}
: Cite has empty unknown parameter: |1=
(
help)
StoltzfusCable_2014
was invoked but never defined (see the
help page).{{
cite book}}
: |journal=
ignored (
help); Check date values in: |year=
(
help)
{{
cite book}}
: |journal=
ignored (
help)
{{
cite book}}
: |journal=
ignored (
help); Check date values in: |year=
(
help)
I have updated the claim by Singer and Ames that a high G+C content could be selectively advantageous with a new reference to Palmeira et al. (2006) Jean R. Lobry 20:05, 3 January 2007 (UTC)
I can't find an answer to this question, and thought I would post it here: How do chromosome numbers change? Say a population of a given species, all of which share the same chromosome number, is isolated from the main population. Time goes by. Now the chromosome numbers are different in the two populations. Does that happen? If so, how? By what mechanisms? -- Serge 23:48, 6 December 2005 (UTC)
Short answer; Polyploidy. There's a very good book on the subject of genome evolution (including the evolution of chromosome number); The Evolution of the Genome by T. Ryan Gregory. You can google Polyploidy I'm pretty sure you'll find plenty of informations on the subject, mostly for plants. -- PhDP 07:03, 24 January 2006 (UTC)
I removed the following sentence:
It was also demonstrated that levels of mutation necessary to cause significant evolution were not present in the environment and would cause sterility; e.g., in fruit flies.
This sentence does not make sense and does not make reference to any recognizable facts. It refers to "levels of mutation . . . present in the environment", but mutation is not present in the environment, it is a process within organisms. By referring to sterility and fruit flies, the statement makes it sound like it is based on some specific experimental result. If so, what is the result? What is the reference?
Here you are referring to levels of radiation to which the flies are exposed, but the disputed statement refers nonsensically to "levels of mutation . . . in the environment". As I said, mutation is not "in the environment". It is an internal process. Mutation is not the same as damage induced by radiation, oxidation, etc: damage is not heritable, but mutations (by definition) are heritable changes. For instance, a TT photodimer is damage, not a mutation; a broken strand is not heritable, but if error-prone repair of the strand introduces nucleotide changes, this represents a mutation.
But just putting the process of mutation back inside the organisms where it belongs would not fix the flawed logic. What principle of mutationism conflicts with the observation that levels of radiation sufficient to produce artificially high levels of mutation (levels that you admit are unnatural) cause sterility in flies? I see no contradiction. Neither apparently did Thomas Hunt Morgan, the mutationist and founder of genetics whom you cite as a source.
This was such a mess, and overlapped so thoroughly with Saltation, that I've gone ahead and boldly merged the materials, and am now rewriting the article to cover the history. Not at all sure we need so much on historiography; and many rough edges remain to be smoothed off, but I hope people will be happy with the progress. Chiswick Chap ( talk) 09:08, 9 May 2017 (UTC)
AFAIK saltationism is opposed to gradualism (not "phyletic gradualism", which opposes punctuated equilibrium, both almost unrelated). Meaning that it allows for or affirms a greater role for mutations causing a more drastic phenotypic difference, as opposed evolution being restricted to gradual variation, the sort of mundane additive variation that accounts for the bulk of ordinary variation in living populations. For concrete but hypothetical examples, in the ancestors of whales, mutations that abort completely or much more dramatically the size of the hind legs/"fins", rather than the ordinary minute variation in size; for eyeless animals, mutations that simply abort the development of the eye (or even one eye, as may be the case with the Mexican tetra), versus genes for progressively more minute but normal eyes, over generations, until they finally reach phenotypic nonexistence. "Freaks", as opposed to "normals". And that is regardless of the "size" or whatever genetic aspect of the mutation at the DNA level -- DNA wasn't even known then. And even "mutationism" doesn't refer to "size" of mutations at the genetic level, but is rather about mutation as a "driving force" alongside selection, rather than just providing the "raw material". That is, if some mutations are recurring enough, they will add to the genetic frequencies of such recurring alleles, at least against neutral variation, and possibly even against some negative selection (maladaptive alleles aren't always completely eliminated, and can even be maintained or increase in frequency if they provide some compensatory advantage, such as sickle cell anemia versus malaria), with the end result possibly coupling alleles of other genes to cope with a recurring maladaptive variation. I can't provide references for such definitions right now, but if I'm not mistaken, this series of articles at the Sandwalk blog will corroborate at least the mutationism "versus" selectionism aspect, mutation as a driver of genetic frequencies. — Preceding unsigned comment added by 189.18.92.181 ( talk) 19:56, 25 June 2017 (UTC)
GA toolbox |
---|
Reviewing |
Reviewer: Dunkleosteus77 ( talk · contribs) 22:09, 10 December 2017 (UTC)