[Odonata-l] Frog legs and odonates - simplistic answer - Occam

Fri Jun 26 22:11:43 PDT 2009

I second Glenn's recommendation of  "Of Moths and Men" A wonderful true story account of the Politics of Science. It was at a Focus Outdoors Conference (circa 1970) sponsored by Mass Audubon that I first heard Ted Sergeant speak about his Underwing Moths! A new use for dad's underutilized Beer as baiting Moths became just another thing a country kid did to keep himself amused... Tonight's moth Blog, A new medium I am trying out for the first time, can be found at: http://dhsmall.blogspot.com/

As for the Odonate predation on larval frog legs, I found the story to be most interesting. Correctly pointed out is the fact this study took place at 3 ponds in England... It would be inappropriate to extrapolate this causal effect too broadly. It is just another piece of this wonderful puzzle we call nature.. I kind of hope we never totally understand it... What fun would that be?

Dave Small
Athol, Massachusetts
dave at dhsmall.net 
www.dhsmall.net 
978-413-1772
  -----Original Message-----
  From: odonata-l-bounces at listhost.ups.edu [mailto:odonata-l-bounces at listhost.ups.edu]On Behalf Of Glenn Corbiere
  Sent: Saturday, June 27, 2009 12:32 AM
  To: Joshua Rose; Odonata-l
  Subject: Re: [Odonata-l] Frog legs and odonates - simplistic answer - Occam

  One of my favorite accounts of oversimplification, and as a reviewer, and not just any reviewer, Ernst Mayr, commented, "a fascinating account of many, many years of observation and experimentation - and of traps" is a book by Judith Hooper (who also happens to be from Amherst) called "Of Moths and Men - The Untold Story of Science and the Peppered Moth" It is simply a joy to read if you love science, bugs, and just plain great storys. Oh, quite a bit of this book is about another local scholar, one Theodore D. Sargent, author of the difficult to find work, "Legion of Night - The Underwing Moths"

  Trust me on this one - get a copy of "Of Moths and Men".  You'll love it.

  Glenn

  Glenn Corbiere 
  100 Prospect St. 
  Chester, MA. 01011-9657 

  www.dragonhunter.net 

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  From: Joshua Rose <opihi at rgv.rr.com>
  To: Odonata-l <odonata-l at listhost.ups.edu>
  Sent: Friday, June 26, 2009 11:19:47 PM
  Subject: Re: [Odonata-l] Frog legs and odonates - simplistic answer - Occam

  Occam's Razor actually tends to be wrong in many ecological cases. Academic science favors oversimplification; everyone wants to boil each effect down to a single cause, that being conducive to winning grants, getting published, and receiving tenure. Real life usually does not cooperate.

  The publications I read concerning that chytrid indicated that it had been present in many areas without causing any undue harm to amphibians; but that other environmental effects - acidification, UV, and so on - degraded the amphibian's immune responses such that the formerly innocuous chytrid became a threat. To the extent that herpetologists carried the chytrid to isolated populations and helped wipe them out, if that did take place, it was A cause but probably not THE cause. A number of frog populations disappeared that had been well known to herpetologists and under study for many years before the chytrid reared its ugly head.

  Another study indicated that non-native Bullfrogs were carriers of the chytrid, hosting it but not being killed off by it, and had helped spread it to at least four continents. African Clawed Frogs are carriers as well. One more piece of the complicated puzzle.

  Back to the issue relevant to this listserv, the odonate larvae eating the legs off of amphibian larvae. The study in question took place in three ponds in one county in England. The answer may be simple in this one small area. There is a LOT more research to do before odonates can be generally accepted as a single worldwide cause of amphibian limb shortages....

  Josh Rose, Ph.D.
  McAllen TX (but soon relocating to Amherst MA)

  On Jun 26, 2009, at 8:38 PM, Richard Rowe wrote:

    Occam says 'go with predation' ... it is the simplest solution and seems consistent with the scope and scale of the data. The herpetology crowd have been very well funded on the basis of dire, apocalyptic warnings revolving about 'canaries in coal mines'. The 'vanishing frogs' events weren't because the system was collapsing or UV radiation on mountain tops but due to a pandemic of an invasive chytrid, most likely vectored by herpetologists; the multilegs wasn't due to unspecified trace toxins but to a well-recognised parasite ... By looking for exotic solutions they have actually endangered their study animals. In Australia there was a decade of discovering new and pristine habitats with healthy populations of frogs, only for the frogs to go bust at the next visit while everything else was doing just fine. Making haste slowly could have been well worthwhile and saved a lot of frogs.

    I think we should sit with Occam until it is shown that some more exotic solution is necessary.

    Lawson, Tamara wrote:

      This article is misleading as it makes the “answer” sound simplistic at best.  My husband is a herpetologist (although he prefers to study snakes) and I’ve occasionally gone to meetings with him and sat in on some of the presentations.  The overwhelming thought of most herpetologists that I’ve talked to (and Nova had a program on amphibians recently as well that stated this idea) is that THERE IS NO SINGLE CAUSE for the mutations (as well as the deaths) observed in amphibians.  Research as shown that some chemicals (this includes man-made ones as well as some secreted by plants’ roots), some parasites (some worms, some fungi, as well as single-celled species, etc.), and some environmental factors (temperature extremes, salinity, predators, etc.) all contribute to current problem of amphibian deformities.  The cause for the world-wide problem is just different in different bodies of water with some research showing multiple cumulative causes and even additive causes in the same pond.  It all goes back to the old saying (or it should be a saying) “don’t look for simple answers in a complicated system”.

      Tamara Lawson, Science Lab. Manager

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      From: odonata-l-bounces at listhost.ups.edu [mailto:odonata-l-bounces at listhost.ups.edu] On Behalf Of Michael Blust
      Sent: Friday, June 26, 2009 9:10 AM
      To: odonata-l at listhost.ups.edu
      Subject: [Odonata-l] Frog legs and odonates - attempt #2

      Legless Frogs Mystery Solved
      from BBC News Online

      Scientists think they have resolved one of the most controversial environmental issues of the past decade: the curious case of the missing frogs' legs.

      Around the world, frogs are found with missing or misshaped limbs, a striking deformity that many researchers believe is caused by chemical pollution.

      However, tests on frogs and toads have revealed a more natural, benign cause. The deformed frogs are actually victims of the predatory habits of dragonfly nymphs, which eat the legs of tadpoles.

      http://snipr.com/kx70t

      ------------------------------------------------------------
      Michael Blust
      Dept. of Natural Science
      Green Mountain College
      Poultney, VT   05764
      802-287-8331
      blustm at greenmtn.edu

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    -- 

Dr Richard Rowe
Zoology & Tropical Ecology
School of Marine & Tropical Biology
James Cook University
Townsville 4811
AUSTRALIA

ph +61 7 47 81 4851
fax +61 7 47 25 1570
JCU has CRICOS Provider Code 00117J 
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