[Taxacom] dinosaurs and wolves (was: another putative arthropod outgroup)

Stephen Thorpe stephen_thorpe at yahoo.co.nz
Tue Oct 2 21:59:13 CDT 2012


Wow, Ken, maybe the entire evolutionary history of species is preserved in deactivated genes? Are there many convincingly established examples of this sort of thing?
 
The only thing that is turned on in my genes right now is ...
 
S :)

________________________________
From: Ken Kinman <kinman at hotmail.com>
To: Stephen Thorpe <stephen_thorpe at yahoo.co.nz>; "taxacom at mailman.nhm.ku.edu" <taxacom at mailman.nhm.ku.edu> 
Sent: Wednesday, 3 October 2012 3:46 PM
Subject: RE: [Taxacom] dinosaurs and wolves (was: another putative arthropod outgroup)


Hi All, 
     I am very hopeful that many such pentastomid genes have not actually been lost, but merely "deactivated" (if you will).  If certain regulatory genes have mutated in such a way that many genes downstream are no longer turned on (and thus resulted in morphological simplifications or total losses), then it is regulatory gene sequences which are most likely to give us much needed information on the ancestral group.  The "deactivated" genes downstream may also be helpful, if they haven't been eliminated over long periods of time.                     
      
       The point is that we know very little about the pentastomid genome, and yet such taxa still seem to take a back seat to intensive sequencing of taxa that don't really advance our knowledge of biodiversity or evolutionary history very much (like individual wolves or polar bears, which have been studied ad nauseum decade after decade after decade).  And I suspect that the cost of one flight of a helicopter hunting down wolves or polar bears once again (for diminishing returns) could fund some really interesting research (including pentastomid sequencing).  Wolves and polar bears are probably sick of being darted, weighed, measured, etc., by another generation of biologists who could be working on poorly studied taxa.  Although I am a mammalogist, if I see another PBS special advertised on the subject of wolves, I think I am going to scream.  Especially if it is funded by governmental agencies.  If the public wants more specials on wolves or
 dinosaurs, let private groups fund it completely.  Governments and universities should be in the business of balance, NOT feeding the public's fascination with certain taxa (especially dinosaurs).  If kids are fascinated by dinosaurs, fine, but their parents should support dinosaur research privately (easily done if they divert a mere 1% of what they readily pump into professional and college sports).  Of course, government could fund FAR greater amounts of conservation and taxonomic research if it just reduced payments into the corporate welfare system.         
                 -------------Ken  



________________________________
Date: Fri, 28 Sep 2012 20:50:23 -0700
From: stephen_thorpe at yahoo.co.nz
Subject: Re: [Taxacom] another putative arthropod outgroup
To: kinman at hotmail.com; taxacom at mailman.nhm.ku.edu


but that is still very "hopeful" ... if pentastomids have lost genes, then we still won't know what they lost exactly, so we can't reconstruct the "groundplan" any more than we can with lost morphology! MAYBE we will find some very specific genetic material shared with a crustacean ingroup, but maybe not ...
 
Stephen


________________________________
From: Ken Kinman <kinman at hotmail.com>
To: Stephen Thorpe <stephen_thorpe at yahoo.co.nz>; "taxacom at mailman.nhm.ku.edu" <taxacom at mailman.nhm.ku.edu> 
Sent: Saturday, 29 September 2012 3:24 PM
Subject: RE: [Taxacom] another putative arthropod outgroup


        I actually think that reduced molecularities (lost genes) will eventually prove more informative than reduced morphologies in such cases.  The trouble is that a small molecular change can result in a cascade yielding a number of morphological changes, so it can be like looking for a needle in a molecular haystack.  If so, what the morphologists call parsimonious in this case may be deceptive.  Not that I am always swayed by molecularists (even when they have lots more data).  I look at each case individually, and weigh morphology vs. molecularity data when they don't agree.  In this case, there is so little molecular data that it seems ridiculous to even invoke parsimony at this stage.       
                  -------------------Ken



________________________________
Date: Fri, 28 Sep 2012 19:59:08 -0700
From: stephen_thorpe at yahoo.co.nz
Subject: Re: [Taxacom] another putative arthropod outgroup
To: kinman at hotmail.com; taxacom at mailman.nhm.ku.edu


at any rate, is there any sound basis for thinking that the DNA associated with reduced morphologies won't itself be reduced/absent, so, unless there is some very specific other DNA shared with a crustacean ingroup (might be, but might not), we are no better off?



________________________________
From: Ken Kinman <kinman at hotmail.com>
To: Stephen Thorpe <stephen_thorpe at yahoo.co.nz>; "taxacom at mailman.nhm.ku.edu" <taxacom at mailman.nhm.ku.edu> 
Sent: Saturday, 29 September 2012 2:47 PM
Subject: RE: [Taxacom] another putative arthropod outgroup


Hi Stephen, 
      Well, just to be fair, I wouldn't call the morphological data in this case "extremely" limited.  It is actually quite impressive how much detail they can see in these Orsten fossils.  My concern in this case is not so much in how limited the morphological data is (even though much of it is from such fossils), but rather how limited the molecular data is on pentastomids.  Sometimes amazing that grant money can be found for sequencing very large numbers of specimens of some species (or even subspecies or populations) of certain taxa, but extremely little on a much higher level taxon like Pentastomida.

                      --------------Ken



________________________________
Date: Fri, 28 Sep 2012 19:05:25 -0700
From: stephen_thorpe at yahoo.co.nz
Subject: Re: [Taxacom] another putative arthropod outgroup
To: kinman at hotmail.com; taxacom at mailman.nhm.ku.edu


>The paleontological morphologists insist that it is unparsimonous to assume that pentastomids have secondarily lost so many crustacean morphologies<
 
It is a general problem with obligate parasite groups, that they are so derived and have lost so many characters that their relationships are obscure. Given that paleontological morphological data is extremely limited (both by the patchiness of the fossil record, and the fact that you can't see much on a fossil specimen), I would look to molecular data on this one (though there is still no guarantee of success). Whether it is "unparsimonious" or not depends on a whole phylogeny, not just part of it taken out of context ...
 
Stephen


________________________________
From: Ken Kinman <kinman at hotmail.com>
To: "taxacom at mailman.nhm.ku.edu" <taxacom at mailman.nhm.ku.edu> 
Sent: Saturday, 29 September 2012 1:47 PM
Subject: [Taxacom] another putative arthropod outgroup


Dear All,      Beside tardigrades and onychophorans, another taxon (Pentastomida) has also long been put forward as an outgroup to euarthropods (or arthropods in general, including fossil taxa).  However, molecular data (18S rRNA and mitochondrial data), along with very limited morphological data, indicates that pentastomids are actually highly modified (morphologically "simplified") maxillopodan crustaceans.        
      Anyone want to weigh in on whether morphologists (especially paleontologists) or molecularists are right on this one?  The paleontological morphologists insist that it is unparsimonous to assume that pentastomids have secondarily lost so many crustacean morphologies, even though they are highly derived due to their parasitic life styles (see weblink below).  The question is whether they are right, or whether the molecularists are just sorely in need of far more molecular data on the pentastomids.  Anyway, if pentastomids are secondarily simplified crustaceans, will tardigrades turn out to also be secondarily simplified arthropods (although perhaps from another branch of arthropods such as chelicerates)?  The debate continues.                      
              ---------------------Ken Kinman                        
http://www.core-orsten-research.de/Publications/PDF_Paper/ulm_team/2011%20CASTELLANI_ETAL.pdf                         
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