Mammal-specific scorpion neurotoxins

[Fet, Victor]

Mammal-specific scorpion neurotoxins, as far as I know, are generally effective on all mammals which are natural enemies of scorpions, but I do not think there was a specific study testing them on all clades of mammals (like elephants :), or for than matter on all clades of amniotes; besides, it's arms race since there is acquired immunity to moderate-level venoms. Their initial evolution could surely be Mesozoic, which for scorpions is only yesterday: modern families are found in Cretaceous.

Victor Fet
Department of Biological Sciences
Marshall University
Huntington, WV 25755-2510 USA
ph. (304) 696-3116, fax (304) 696-3243
http://www.science.marshall.edu/fet/euscorpius/Fet.htm 



-----Original Message-----
From: Taxacom Discussion List [mailto:TAXACOM at LISTSERV.NHM.KU.EDU] On Behalf Of Kevin Thiele
Sent: Tuesday, February 07, 2006 5:14 PM
To: TAXACOM at LISTSERV.NHM.KU.EDU
Subject: [TAXACOM] Mammal-specific scorpion neurotoxins

>P.S.  Are mammal-specific neurotoxins of scorpions effective against 
>certain clades of mammals, or against mammals in general?  If the 
>latter, then such toxins could have easily developed during the very 
>long Mesozoic history of mammals.

Must it be the case that mammal-specific neurotoxins evolved in response to mammals? I believe that funnel-web spider (Atrax: Australia) venom is highly toxic to primates but much less so to other mammals - but this surely is purely accidental, since primates (Homo only) are very late arrivals to Australia.

Cheers - k


-----Original Message-----
From: Taxacom Discussion List [mailto:TAXACOM at LISTSERV.NHM.KU.EDU] On Behalf Of Ken Kinman
Sent: Wednesday, 8 February 2006 9:24 AM
To: TAXACOM at LISTSERV.NHM.KU.EDU
Subject: Re: [TAXACOM] RE: mammals morphologically evoluated a lot since the Ceno zoïcum, invertebrates did not.Why?

On Tue, 7 Feb 2006 11:30:19 -0500, Fet, Victor <fet at MARSHALL.EDU> wrote:

For scorpions, it is always taken for granted but might not be true....

there are indeed major groups of scorpions which did not survive K-T extinction....

 the best example in scorpion context is evolution of mammal-specific neurotoxins, obviously Cenozoic!
*********************************************************
Hi Victor,
     I would certainly agree that many major scorpion groups died out
*before* the K-T extinction (most well before the Cretaceous even began).  I suppose some families of scorpions could have gone extinct the end of the Cretaceous, but with so few fossils (mostly from the Middle Cretaceous?), how would you know that the end-Cretaceous extinction did them in?  Whatever scorpion families existed at the end of the Cretaceous, I still suspect a majority of them survived (although with fewer genera than before the extinction).  Not a *catastrophic* extinction like that which wiped out the vast majority of families of birds at the end of the Cretaceous.  Birds just barely made it through.
  ---Cheers,
           Ken Kinman
P.S.  Are mammal-specific neurotoxins of scorpions effective against certain clades of mammals, or against mammals in general?  If the latter, then such toxins could have easily developed during the very long Mesozoic history of mammals.