Register | Sign In


Understanding through Discussion


EvC Forum active members: 65 (9162 total)
5 online now:
Newest Member: popoi
Post Volume: Total: 915,817 Year: 3,074/9,624 Month: 919/1,588 Week: 102/223 Day: 13/17 Hour: 0/1


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Author Topic:   "Macro" vs "Micro" genetic "kind" mechanism?
Rrhain
Member
Posts: 6351
From: San Diego, CA, USA
Joined: 05-03-2003


Message 76 of 248 (123722)
07-11-2004 8:25 AM
Reply to: Message 62 by RAZD
07-06-2004 2:54 PM


Re: Limits to Dachsunds
RAZD writes:
quote:
This is why you cannot breed horses to run at the speed of sound. There is a point where bones get too weak, heart and lungs not capable to keep pace even though the legs are "willing"
The best example of this are the "double muscled" Belgian Blue cows. They have a genetic mutation in the myostatin gene, disabling it, which results in excessive hypertrophy of skeletal muscle cells. The bulls are so large that they tend to be incapable of breeding naturally: They would break the backs of the cows. Instead, they have to be ejaculated and the cows bred artificially or the bull needs to be put in a harness and lowered onto the cow.
There is medical research done into how this can be used for human diseases such as muscular dystrophy...and worry that it would then be used as genetic doping by athletes.

Rrhain
WWJD? JWRTFM!

This message is a reply to:
 Message 62 by RAZD, posted 07-06-2004 2:54 PM RAZD has seen this message but not replied

Replies to this message:
 Message 85 by Mammuthus, posted 07-12-2004 10:25 AM Rrhain has not replied

  
pink sasquatch
Member (Idle past 6022 days)
Posts: 1567
Joined: 06-10-2004


Message 77 of 248 (123787)
07-11-2004 6:26 PM
Reply to: Message 73 by Rrhain
07-11-2004 8:13 AM


chromosome analysis context
Um, no. XO individuals develop as female. It's called "Turner's Syndrome."
You are referring to an entirely different context with Turner's Syndrome, that is, the sudden loss of the Y chromosome from the human genome as it currently stands.
We were discussing it in an evolutionary context, and theories that the Y chromosome is gradually shrinking, and that necessary Y genes are jumping to autosomes and gaining new regulatory mechanisms.
If the proponents of this theory are correct, in a 100,000 or so human generations there may be "XO" males.

This message is a reply to:
 Message 73 by Rrhain, posted 07-11-2004 8:13 AM Rrhain has not replied

  
pink sasquatch
Member (Idle past 6022 days)
Posts: 1567
Joined: 06-10-2004


Message 78 of 248 (123791)
07-11-2004 6:34 PM
Reply to: Message 75 by Rrhain
07-11-2004 8:18 AM


nitpick
And then there's birds where the sex chromosomes go the other way: XX individuals are male and XY individuals are female.
It's my understanding that nomenclature is different when the female is heterogametic: "ZZ" males and "WZ" females.

This message is a reply to:
 Message 75 by Rrhain, posted 07-11-2004 8:18 AM Rrhain has replied

Replies to this message:
 Message 79 by Rrhain, posted 07-11-2004 11:51 PM pink sasquatch has replied

  
Rrhain
Member
Posts: 6351
From: San Diego, CA, USA
Joined: 05-03-2003


Message 79 of 248 (123848)
07-11-2004 11:51 PM
Reply to: Message 78 by pink sasquatch
07-11-2004 6:34 PM


Re: nitpick
pink sasquatch responds to me:
quote:
quote:
And then there's birds where the sex chromosomes go the other way: XX individuals are male and XY individuals are female.
It's my understanding that nomenclature is different when the female is heterogametic: "ZZ" males and "WZ" females.
True. As my bio text puts it, birds, moths, and butterflies have this trait of the males being XX and the females being XY and "to avoid confusion, this is usually expressed as ZZ (male) and ZW (female)."
And with regard to XO, I understand now what you were talking about with the genes from the Y moving to other chromosomes.
Sex determination is a varied and complex thing. Bees have diploid individuals being female and haploid individuals being male. Drosophila, however, it's the ratio of X chromosomes to autosomes. That is, XXN individuals are female (that is, XXO and XXY are female) while XN individuals are male (that is, XO and XY are male). Interestingly, XO males are sterile while XXY females are fertile. And then there's grasshoppers where females are XX and males are XO.

Rrhain
WWJD? JWRTFM!

This message is a reply to:
 Message 78 by pink sasquatch, posted 07-11-2004 6:34 PM pink sasquatch has replied

Replies to this message:
 Message 80 by RAZD, posted 07-12-2004 12:05 AM Rrhain has replied
 Message 82 by pink sasquatch, posted 07-12-2004 12:48 AM Rrhain has replied

  
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 80 of 248 (123854)
07-12-2004 12:05 AM
Reply to: Message 79 by Rrhain
07-11-2004 11:51 PM


Re: nitpick
looks like there are lots of ways for 'sex' to work ... how many are independantly evolved and how many derived from other systems? Looks like the world is more wonderous the more you know.
and if you have XXY, XXO, XY and XO types which two get the free pass on the ark (assuming flies are not "clean" ... )?

we are limited in our ability to understand
by our ability to understand
RebelAAmerican.Zen[Deist
{{{Buddha walks off laughing with joy}}}

This message is a reply to:
 Message 79 by Rrhain, posted 07-11-2004 11:51 PM Rrhain has replied

Replies to this message:
 Message 81 by Rrhain, posted 07-12-2004 12:22 AM RAZD has seen this message but not replied

  
Rrhain
Member
Posts: 6351
From: San Diego, CA, USA
Joined: 05-03-2003


Message 81 of 248 (123860)
07-12-2004 12:22 AM
Reply to: Message 80 by RAZD
07-12-2004 12:05 AM


Re: nitpick
RAZD responds to me:
quote:
and if you have XXY, XXO, XY and XO types which two get the free pass on the ark (assuming flies are not "clean" ... )?
Well, the XO males are sterile, so they don't get to come. And if we're going to maintain the current genetic outcome, we'd need the XXY female so that the double-X gametes can be created.

Rrhain
WWJD? JWRTFM!

This message is a reply to:
 Message 80 by RAZD, posted 07-12-2004 12:05 AM RAZD has seen this message but not replied

  
pink sasquatch
Member (Idle past 6022 days)
Posts: 1567
Joined: 06-10-2004


Message 82 of 248 (123863)
07-12-2004 12:48 AM
Reply to: Message 79 by Rrhain
07-11-2004 11:51 PM


Re: nitpick
Sex determination is a varied and complex thing...
Sure is... and you didn't even get into the hermaphrodites...
Rrhain - I think it was you that mentioned "lesbian" lizards in one of the many homosexuality threads - all female but reproducing sexually.
Are they really more like hermaphrodites?
Is it known if they have the equivalent of sex chromosomes?
Would "unisexual" be an apt term for their reproduction?
If there's a decent publication out there I'd like to check it out.
(If I only imagined you talking about lesbian lizards, ignore me.)

This message is a reply to:
 Message 79 by Rrhain, posted 07-11-2004 11:51 PM Rrhain has replied

Replies to this message:
 Message 83 by Rrhain, posted 07-12-2004 1:13 AM pink sasquatch has not replied
 Message 86 by arachnophilia, posted 07-12-2004 10:53 AM pink sasquatch has not replied

  
Rrhain
Member
Posts: 6351
From: San Diego, CA, USA
Joined: 05-03-2003


Message 83 of 248 (123867)
07-12-2004 1:13 AM
Reply to: Message 82 by pink sasquatch
07-12-2004 12:48 AM


Re: nitpick
pink sasquatch responds to me:
quote:
Rrhain - I think it was you that mentioned "lesbian" lizards in one of the many homosexuality threads - all female but reproducing sexually.
No, 'twasn't me. Alas, I don't recall who and I don't have the motivation to go looking.
quote:
Are they really more like hermaphrodites?
No, they are all female. This form of reproduction is called "parthenogenesis." In the particular lizards being discussed, they cannot reproduce unless they engage in sexual activity...but this activity doesn't actually result in any genetic material being exchanged. And since all the individuals are female, they're lesbian. The sex act triggers the reproductive cycle.
There is another kind of lizard that switches between sexual and parthenogenetic reproduction, depending upon the conditions the population finds itself in. When variation is needed, males start being born to allow recombination and then they go back to all female.

Rrhain
WWJD? JWRTFM!

This message is a reply to:
 Message 82 by pink sasquatch, posted 07-12-2004 12:48 AM pink sasquatch has not replied

Replies to this message:
 Message 84 by RAZD, posted 07-12-2004 9:31 AM Rrhain has not replied

  
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 84 of 248 (123909)
07-12-2004 9:31 AM
Reply to: Message 83 by Rrhain
07-12-2004 1:13 AM


Re: nitpick
would that make them vary sexual?

This message is a reply to:
 Message 83 by Rrhain, posted 07-12-2004 1:13 AM Rrhain has not replied

  
Mammuthus
Member (Idle past 6475 days)
Posts: 3085
From: Munich, Germany
Joined: 08-09-2002


Message 85 of 248 (123918)
07-12-2004 10:25 AM
Reply to: Message 76 by Rrhain
07-11-2004 8:25 AM


Re: Limits to Dachsunds
Like cows like people...there was a kid in Germany born with a homozygous mutation in the myostatin gene..he is 5 now, built like a bodybuilder and very strong. It remains to be seen what the long term physiological effects will be on this child, but given his phenotype, there is talk of applications for muscular dystrophy i.e. compensating for the dystrophic effects by blocking myostatin production.

This message is a reply to:
 Message 76 by Rrhain, posted 07-11-2004 8:25 AM Rrhain has not replied

  
arachnophilia
Member (Idle past 1344 days)
Posts: 9069
From: god's waiting room
Joined: 05-21-2004


Message 86 of 248 (123921)
07-12-2004 10:53 AM
Reply to: Message 82 by pink sasquatch
07-12-2004 12:48 AM


lesbian lizards
Rrhain - I think it was you that mentioned "lesbian" lizards in one of the many homosexuality threads - all female but reproducing sexually.
nope, that was me. the lizards are the desert grassland whiptail, cnemidophorus uniparens.
Are they really more like hermaphrodites?
nope. they contain only female genitalia. the process used to trigger reproduction is sexual, lizard to lizard genital contact, but the actual reproduction is technically asexual. they're cloners. all of the lizards in the population share exactly the same genes, apparently.
Is it known if they have the equivalent of sex chromosomes?
yes. they're all female.
Would "unisexual" be an apt term for their reproduction?
yup. "parthenogenetic unisexual pseudocopulators" is what they're called. basically, in english, it means they're virgin-birthing one-sexed mutual-masturbators.
here's a link: nerve.com®
as a side note, what bugs me about them isn't the lesbian sex, but asexual reproduction it triggers. these lizards don't exactly have a gene pool, per se. they're all clones, exactly alike genetically. basically, evolution has stopped for these lizards. if something were to come along that would endanger them, they'd all be gone, because natural selection for them is all or nothing. they have no way to adapt.
This message has been edited by Arachnophilia, 07-12-2004 09:53 AM

This message is a reply to:
 Message 82 by pink sasquatch, posted 07-12-2004 12:48 AM pink sasquatch has not replied

Replies to this message:
 Message 87 by RAZD, posted 07-12-2004 11:50 AM arachnophilia has not replied
 Message 88 by Mammuthus, posted 07-12-2004 11:53 AM arachnophilia has replied

  
RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 87 of 248 (123930)
07-12-2004 11:50 AM
Reply to: Message 86 by arachnophilia
07-12-2004 10:53 AM


Re: lesbian lizard clones
but
each {one \ clone lineage} should be accumulating mutations and adapting in much the same way the "usual suspects" of asexual organisms adapt, and natural selection would pick the individuals to survive to breed in the same way.
and population size and genetic diversity would be critical determining factors in species success.

we are limited in our ability to understand
by our ability to understand
RebelAAmerican.Zen[Deist
{{{Buddha walks off laughing with joy}}}

This message is a reply to:
 Message 86 by arachnophilia, posted 07-12-2004 10:53 AM arachnophilia has not replied

Replies to this message:
 Message 90 by Loudmouth, posted 07-12-2004 1:37 PM RAZD has replied

  
Mammuthus
Member (Idle past 6475 days)
Posts: 3085
From: Munich, Germany
Joined: 08-09-2002


Message 88 of 248 (123931)
07-12-2004 11:53 AM
Reply to: Message 86 by arachnophilia
07-12-2004 10:53 AM


Re: lesbian lizards
Actually, I don't think it is such a problem. Just like bacteria and other asexual reproducing organisms, the lizards will still sustain mutations subject to selection. If asexual reproduction procluded evolution we would not see as much adaptation among bacteria as we do. However, they will be much slower to respond to change as sexual reproduction is much better at spreading variation than mistakes during clonal propagation...still strange stuff in any event.

This message is a reply to:
 Message 86 by arachnophilia, posted 07-12-2004 10:53 AM arachnophilia has replied

Replies to this message:
 Message 89 by arachnophilia, posted 07-12-2004 12:29 PM Mammuthus has replied

  
arachnophilia
Member (Idle past 1344 days)
Posts: 9069
From: god's waiting room
Joined: 05-21-2004


Message 89 of 248 (123940)
07-12-2004 12:29 PM
Reply to: Message 88 by Mammuthus
07-12-2004 11:53 AM


Re: lesbian lizards
i knew i was missing something. i suppose random mutation and genetic drift through transcription errors are still in play. i should stop posting on no sleep, i must sound like an idiot lol.
although, i would imagine it still does leave them especially susceptable to extinction.

This message is a reply to:
 Message 88 by Mammuthus, posted 07-12-2004 11:53 AM Mammuthus has replied

Replies to this message:
 Message 94 by Mammuthus, posted 07-13-2004 4:13 AM arachnophilia has replied
 Message 96 by Rrhain, posted 07-14-2004 4:53 AM arachnophilia has not replied

  
Loudmouth
Inactive Member


Message 90 of 248 (123959)
07-12-2004 1:37 PM
Reply to: Message 87 by RAZD
07-12-2004 11:50 AM


Re: lesbian lizard clones
quote:
but
each {one \ clone lineage} should be accumulating mutations and adapting in much the same way the "usual suspects" of asexual organisms adapt, and natural selection would pick the individuals to survive to breed in the same way.
As Mammuthus pointed out above, sexual reproduction aids in the dispersal of genotypes. Bacteria, also cloners, have the advantage of multiplying quickly (eg generation time of 20 minutes) as compared to lizards which only reproduce once a year. If the population were brought to 1% of current size the whiptails would be in serious danger.

This message is a reply to:
 Message 87 by RAZD, posted 07-12-2004 11:50 AM RAZD has replied

Replies to this message:
 Message 91 by RAZD, posted 07-12-2004 2:31 PM Loudmouth has replied

  
Newer Topic | Older Topic
Jump to:


Copyright 2001-2023 by EvC Forum, All Rights Reserved

™ Version 4.2
Innovative software from Qwixotic © 2024