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Author | Topic: what is a mutation? | |||||||||||||||||||
lbhandli Inactive Member |
In an effort to keep threads clear--I have moved this over from The Definition of the Modern Synthesis to address thmsberry's claims of random mutations. I will be taking quotes from both posts 2 and 5 in Definition of the Modern Synthesis
From Thmsberry:
quote: quote: Random issue dealt with in another thread...How so? I see it as exactly that ambiguity Percy points out in describing the use of the term mutation. Percy: quote: Let me quote some specific sources: Lewin, Benjamin. Genes. 1997. Oxford University Press"Mutations are heritable alterations that change genetic information." Pg. 65 Burns, W. George and Paul Bottino. The Science Of Genetics. 6th Ed. 1989. Macmillan"A mutation then, is a sudden, heritable change in the structure of genetic material." Griffiths, Anthony JF, Jeffrey H. Miller, David T. Suzuki, Richard C. Lewontin, and William M. Gelbart. An Introduction to Genetic Analysis. 5th Ed. WH Freeman (6th edition the same on the same issues--1996) "Mutation: Process that produces a gene or chromosom set differing from the wild type. " "Wild Type: The genotype or phenotype that is found in nature or instead of lab stock" Hartl, Daniel L, David Freifelder, and Leon A Snyder. Basic Genetics. 1988. Mutation: "a heritable alteration in a gene." Strickberger, Monroe W. Evolution. 3rd Ed. 2000. Jones and Bartlett Publishing. "A change in the nucleotide sequence of genetic material whether by substitution, duplication, insertion, deletion, or inversion." Futuyma, Douglass. Evolutionary Biology. 3rd. Ed. 1998. Sinauer Associates, Inc. "An alteration of genetic material, usually of a DNA sequence, that gives rise to a new allele (however distinguished) or haplotype." Rieger, R., A. Michaels, M. M. Green. Glossary of Genetics: Classics and Molecular. 5th Ed. 1991. Springer-? "Any heritable alteration whether a singe base change in DNA (or RNA) or a large-scale rearrangement, in the genetic material of a living cell or virus." One of the best descriptions is probably found here that demonstrates that ambiguity:Brown, T.A. Genetics: A Molecular Approach. 1990. Chapman and Hall. "Strictly speaking a mutation is any alteration in the nucleotide sequence of DNA molecule, but the term is generally used to refer to a relatively small-scale change, often thought not always affecting just a single base pair. In contrast recombination involves the exchange of segments of polynucleotides between different DNA molecules and can give rise to quite substantial rearrangements. A third type of event, transposition, provides a link between the two, it occurs by recombination but often results in a mutation." quote: The above should create some question of your position at best. Mutation is used in different contexts. I think Brown's definition is quite good at pointing out the different uses.
quote: Percy is more charitable than I am on the issue. The site is to a college level class based on a text that is cited. You wanted texts--I provided several above that are exactly in agreement with the definition. Perhaps you can explain to me exactly what is pathetic about it again?
quote: Percy castigated me for not saying what the book was, but I didn't because it would be so glaringly obvious if you had bothered to look it up. As usual you undertook no effort to look anything up. The book is entitled Horizontal Gene Transfer, eds Michael Syvanen and Clarence I. Kado. 1998. Chapman and Hall. What major assumption are you disagreeing with? I'll be happy to point you to his specific work that deals with that major assumption. What you disagree with above is unclear so I cannot respond. However, I would say that given the quote from him, he does see horizontal transfer as a mutational mechanism. Additionally, Krassilov's article in the book, "Character Parallelism and Reticulation in the Origin of Angiosperms" describes horizontal transfer as a mechanism for macromutations to spread. I do agree the term is used in different contexts differently, but it seems to me that in the context of evolution, such a process is indeed a mutation. Other articles also refer to the insertions and deletions in context of a mutation in reference to HGT.
quote: In generically discussing transposons including foreign transposons, Lewin (cited above) says:
[QUOTE]Transposons are interesting not just for the mechanisms involved in the manipulation of DNA, but also for the evolutionarly consequences of their mobility. They may provide the major source of mutations in the genome.[quote]
In Griffiths et al. they make no effort in discussing transposons that are entirely intra genomic and inter genomic when they refer to tranposon mutatants. Most texts simply don't cover the issue very well, btw. So claiming they are definitive one way or another is simply not very useful.
quote: I just wet my knickers. Thank you for a good laugh. We are discussing the same thing. You have now been provided very specific sources that demonstrate the definitions provided so far are quite typical in texts and other scientific sources. I'll admit there is differing use of the terms, but your claims to be the sole source of authority on such issues is not valid. You asked me to define horizontal gene transfer, and frankly I am a bit confused. I use it as a horizontal transfer is between distantly related species that don't commonly share genetic material through reproduction like activities. The thing that confused me is you don't define it in your post, but fumble around with examples that don't appear to have any consistency with them.
quote: Several who have discussed issues with you have specifically cited your inability to address issues forthrightly. I suggest that while I may be unclear at times, it is a rare moment where you are clear.Cheers, Larry
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lbhandli Inactive Member |
quote: I offered several sources that define mutation broadly. When they define mutations in more detail they leave it unclear as to how such a change would be regarded. My original question regarded wouldn't such a change be a mutation if it is a change in the genotype. I provided the editor of a book on Horizontal Gene Transfer referring to HGT as a mutational mechanism and another author in that book also referring to it in that way. A third author describes the effects in terms of mutations. This is still unclear because Syvanen was referring to a specific case. So I asked him and got this response on talk.origins:
quote: Ron's comments were:
quote: When deja/google picks up the thread, I'll post the urls. Additionally Mike added this:
quote: I'm going to be adding that to the Links and Information section because it has 5 reprints of articles by Syvanen on HGTs.
quote: The interesting things is that the texts don't draw clear lines between the two. While I agree one might be better labeled gene flow, the texts I read were not that clear. And it appears that Okimoto and Syvanen disagree in part at least. The confusion is largely over the complexity of process. And in reference to the original discussion, this seems to me to be why such events might be included in the Modern Synthesis as Futuyma explains the tenets. The understanding of genetics was so minimal that any sort of event like these would probably fit. The counter to this is that such events may be almost saltational in nature which certainly would be counter to the Modern Synthesis. The first of the papers by Syvanen seems to suggest that is a possibility. From what I can gather at this point, HGTs may be mutations in the traditional sense, but other times they may not be depending on the exact processes and material exchanged.
quote: What evidence do you have for this. I found it to be much less clear. Please provide sources that are very clear. I found one expert who finds it much less clear than you assert it is and I find the texts get very vague on this very point.
quote: I've provided an extensive list that are quite ambiguous on the issue and asked an author in the field I would suggest that it is your turn to do a little work.
quote: I am arguing that the texts aren't real clear. Of course the problem is that most of them don't really address HGT in any detail so I'm not sure how one could make such a strong conclusion as you claim. What sources are you using? Cheers,Larry Handlin [This message has been edited by lbhandli (edited 03-13-2001).]
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