Tim Tyler  wrote in
news:c25pfo$4lk$1{at}darwin.ediacara.org: 

> William Morse  wrote or quoted:
>> Tim Tyler  wrote in

>> > Old, non-variable traits (of any sort) need not /necessarily/
>> > represent adaptations.
>> 
>> I disagree strongly. If they are not being fixed by stabilizing 
>> selection, they will drift.
> 
> You criticism doesn't address my point, though.  Locked-in accidents
> *are* kept in place by stabilizing selection.  If they change, then
> all the adaptations that depend on them crash.
> 
> Your criticsim only deals with traits *not* fixed by stabilising
> selection. 
> 
> A locked-in accident is certainly not like that.  Attempts to change
> such traits meet strong resitsance from selection.
> 
> However that does not mean they didn't originally arise from the
> founder effect - or some such - and at the time they first formed,
> they may well have been near-neutral.
 
> [snip blood types]

Sorry- I misread you. Even though you specifically discussed lock-ins, I 
read it as linkage - which can also limit variation in selectively 
neutral traits but which is subject to unlinkage given enough time or a 
large enough population. I will concede that lock-ins are an exception to 
my default assumptions - but fortunately for myself I _did_  point out 
that they were only assumptions, subject to correction by better data:-)

And I will further note that non-adaptive lock-ins are unlikely to 
represent very many traits in old, widespread, morphologically stable 
species, because such species are still subject to competition from other 
species and have been for a long time. So they cannot afford too much 
extra baggage. 

Yours,

Bill Morse
---
þ RIMEGate(tm)/RGXPost V1.14 at BBSWORLD * Info{at}bbsworld.com

---
 * RIMEGate(tm)V10.2áÿ* RelayNet(tm) NNTP Gateway * MoonDog BBS
 * RgateImp.MoonDog.BBS at 3/5/04 6:40:35 AM