Understanding through Discussion


Welcome! You are not logged in. [ Login ]
EvC Forum active members: 86 (8945 total)
356 online now:
Newest Member: ski zawaski
Happy Birthday: ONESOlivia, perfect
Post Volume: Total: 865,616 Year: 20,652/19,786 Month: 1,049/2,023 Week: 0/557 Day: 0/101 Hour: 0/0


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Author Topic:   Genetic load: can someone explain?
slevesque
Member (Idle past 2957 days)
Posts: 1456
Joined: 05-14-2009


Message 25 of 53 (535799)
11-18-2009 2:04 AM
Reply to: Message 22 by Coyote
11-17-2009 9:13 PM


Re: Deleterious mutations
You seem to be equivocating the fact of evolution with the theory of evolution, invoquing that since we know the former is ''true'' (I don't think it is, but from your point of view) then obviously the later is true as well.

But it doesn't follow. Neo-Darwinian evolution as a theory uses two mechanisms: mutations and natural selection. This is supposed to be able to explain the fact of evolution shown by the fossil record, amongst other things (which by the way, shows much more ponctuated equilibrium in my humble opinion.)

But if Mutation+NS is being discovered to be unable to provide the fact of evolution, then other avenues must be searched. Possibly a third mechanism that, added with the two others, can be shown to produce the evolution of a population. At this stage, the fact of evolution has not being challenged.

But I do not think, and you will probably agree with me, that you can really bring up the fact of evolution, and through it protect the Neo-Darwinian theory of evolution. If simple mutations+NS is shown to be unable to produce the fact of evolution, than other avenues must be searched.

Rereading your post before sending mine, this is not exactly what you are doing. I still post it anyways as I find it a good addition to the overall discussion.


This message is a reply to:
 Message 22 by Coyote, posted 11-17-2009 9:13 PM Coyote has not yet responded

  
slevesque
Member (Idle past 2957 days)
Posts: 1456
Joined: 05-14-2009


Message 26 of 53 (535800)
11-18-2009 2:08 AM
Reply to: Message 24 by Coyote
11-17-2009 10:23 PM


Re: Deleterious mutations
I think he was more talking about the evidence brought up by modern genetics. (number of mutations per person per generation. Beneficial to deleterious ratio of these mutations. The danegrs of mutational meltdown, etc.)

You always seem to be bringing up the fall for whatever reason I don't know. And you tag it here as the evidence Phydeaux is talking about, which it clearly was not.


This message is a reply to:
 Message 24 by Coyote, posted 11-17-2009 10:23 PM Coyote has responded

Replies to this message:
 Message 35 by Coyote, posted 11-18-2009 10:58 AM slevesque has not yet responded

  
slevesque
Member (Idle past 2957 days)
Posts: 1456
Joined: 05-14-2009


Message 27 of 53 (535801)
11-18-2009 2:09 AM
Reply to: Message 19 by Phydeaux
11-17-2009 4:35 PM


Re: Epistasis and fitness
I think Dr. Sanford sometimes peer-reviews papers in the domain of population genetics, so he is pretty qualified in the field I would guess.

This message is a reply to:
 Message 19 by Phydeaux, posted 11-17-2009 4:35 PM Phydeaux has responded

Replies to this message:
 Message 29 by Phydeaux, posted 11-18-2009 2:39 AM slevesque has responded

  
slevesque
Member (Idle past 2957 days)
Posts: 1456
Joined: 05-14-2009


(1)
Message 31 of 53 (535810)
11-18-2009 4:24 AM
Reply to: Message 29 by Phydeaux
11-18-2009 2:39 AM


Re: Epistasis and fitness
Yeah I read his book. And well I do remember the part you are citing implicitly about his opinion of population geneticists.

But I do remember that recently he peer-reviewed an article about population genetics (specifically selection cost), the other peer-reviewers (they were 4 or 5 in total) were Crow, Kondrashov and one or two others.

So well I would think that he is considered knowledgeable enough to peer-review papers on the subject, than he probably is enough to write on it.


This message is a reply to:
 Message 29 by Phydeaux, posted 11-18-2009 2:39 AM Phydeaux has responded

Replies to this message:
 Message 33 by Phydeaux, posted 11-18-2009 9:39 AM slevesque has not yet responded

  
slevesque
Member (Idle past 2957 days)
Posts: 1456
Joined: 05-14-2009


Message 42 of 53 (535890)
11-18-2009 3:34 PM
Reply to: Message 40 by PaulK
11-18-2009 1:04 PM


Re: Deleterious mutations
It is because, as WK said, you are assuming the number of mutations per individual per generation is the same in Drosophilia then in humans. But of course it is not.

The reason for this is simple: the mutations happen during transcription. Since both Drosophilia and humans are both eukaryotic, they have the same transcription method, and so the same amount of mutations per transcription. However, since a human generation is 20years, by the time the individual does reproduce, his reproductive cells that produce the spermatozoides (sorry I don't have the exact terminology) have duplicated a lot more than if it was only a half-year generation for example, and so they have more mutations per generation

And so, the smaller generation time is actually and advantage to last longer, since if natural selection can only act after 20years of ccumulatio nin the case of humans, in the case of drosophilia, it can act every couple of days, which in turn runs counter to mutation accumulations. In fact, the most optimal is selection between each transcription, which happens in the unicellulr organisms.

AbE This reply would be actually more approriate in a reply to message no38 by PaulK, I clicked the wrong one.

Edited by slevesque, : No reason given.


This message is a reply to:
 Message 40 by PaulK, posted 11-18-2009 1:04 PM PaulK has responded

Replies to this message:
 Message 43 by PaulK, posted 11-18-2009 5:16 PM slevesque has responded
 Message 44 by Wounded King, posted 11-18-2009 5:30 PM slevesque has responded

  
slevesque
Member (Idle past 2957 days)
Posts: 1456
Joined: 05-14-2009


Message 45 of 53 (535927)
11-18-2009 5:44 PM
Reply to: Message 44 by Wounded King
11-18-2009 5:30 PM


Re: Deleterious mutations
Yeah my bad, I usd the word transcription instead of replication.

But, if we would reproduce at age 10, wouldn't the germ cells have replicated twice as less, and so the DNA they would contain would have had twice as less mistakes as compared to the parents DNA ? If not, why ?


This message is a reply to:
 Message 44 by Wounded King, posted 11-18-2009 5:30 PM Wounded King has responded

Replies to this message:
 Message 47 by Wounded King, posted 11-18-2009 6:03 PM slevesque has responded

  
slevesque
Member (Idle past 2957 days)
Posts: 1456
Joined: 05-14-2009


Message 46 of 53 (535928)
11-18-2009 5:45 PM
Reply to: Message 43 by PaulK
11-18-2009 5:16 PM


Re: Deleterious mutations
If your positions is that humans are in a worse position, why are you asking why drosophilia are still around ?

This message is a reply to:
 Message 43 by PaulK, posted 11-18-2009 5:16 PM PaulK has responded

Replies to this message:
 Message 48 by PaulK, posted 11-18-2009 6:12 PM slevesque has not yet responded

  
slevesque
Member (Idle past 2957 days)
Posts: 1456
Joined: 05-14-2009


Message 49 of 53 (535960)
11-18-2009 10:19 PM
Reply to: Message 47 by Wounded King
11-18-2009 6:03 PM


Re: Deleterious mutations
The germ cell don't undergo meiosis before puberty, but they still have to undergo mitosis in order to produce other germ cells from. Mutations would still accumulate in the germ cell lineages even during mitosis.

This message is a reply to:
 Message 47 by Wounded King, posted 11-18-2009 6:03 PM Wounded King has responded

Replies to this message:
 Message 50 by Wounded King, posted 11-19-2009 4:26 AM slevesque has responded

  
slevesque
Member (Idle past 2957 days)
Posts: 1456
Joined: 05-14-2009


Message 51 of 53 (536048)
11-19-2009 1:15 PM
Reply to: Message 50 by Wounded King
11-19-2009 4:26 AM


Re: Deleterious mutations
I agree that a larger genome will of course make for a higher mutation per individual rate. (and it probably would be a linear relationship I would guess)

But couldn't the effects would be cumulative ?
This is all new territory for me, so I still have questions.

So we start creating our germ cell populations during development. Once it is 'created', do these germ cells divide frequently or do they stay ''dormant'' until puberty ? Because I would think that if they did have to divide in order to maintain their population, then this would introduce once again more mutations in the genome the longer the individual would have to 'wait' until puberty/reproduction.


This message is a reply to:
 Message 50 by Wounded King, posted 11-19-2009 4:26 AM Wounded King has responded

Replies to this message:
 Message 52 by Wounded King, posted 01-22-2010 8:23 AM slevesque has responded

  
slevesque
Member (Idle past 2957 days)
Posts: 1456
Joined: 05-14-2009


Message 53 of 53 (549285)
03-05-2010 2:57 PM
Reply to: Message 52 by Wounded King
01-22-2010 8:23 AM


Re: Deleterious mutations
I never came back here either

That's interesting to know, and intuitively it makes sense.

Of course, having numbers to compare with drosophilia would have closed out the answer to PaulK's question about why drosophilia are still around.


This message is a reply to:
 Message 52 by Wounded King, posted 01-22-2010 8:23 AM Wounded King has not yet responded

  
Newer Topic | Older Topic
Jump to:


Copyright 2001-2018 by EvC Forum, All Rights Reserved

™ Version 4.0 Beta
Innovative software from Qwixotic © 2019