From: rigg@osnome.che.wisc.edu (Tim Rigg)
Subject: Re: Self Regulating Populations
Organization: University of Wisconsin-Madison, Chemical Engineering
Date: 31 Aug 92 10:29:14
In-reply-to: russ@wpg.com's message of Sun, 30 Aug 1992 01:57:02 GMT

In article <BtrxF6.496@wpg.com> russ@wpg.com (Russell Lawrence) writes:
   From article <RIGG.92Aug28122441@osnome.che.wisc.edu>, by rigg@osnome.che.wisc.edu (Tim Rigg):
   tr> I read this article and was quite disappointed by what it said and
   tr> didn't say.  I was expecting it to explain how the mechanism would
   tr> allow populations to control their own population, regardless of
   tr> predation.  However, it said nothing of the sort.  ALL it said is that
   tr> lower body fat lowers fertility.  That's all...  

   Did you miss the part where the author pointed out that lower levels of
   adipose tissue will obliterate fertility altogether?

The author stated that lower levels _can_ prevent fertility.  The
extremely undernourished and relatively fat-free women of some
developing countries show that fertility is not prevented.  It is just
lowered. 

   tr> That is a point almost
   tr> all have conceded quite a while ago.  What it does NOT say is that the
   tr> decrease means a heck of a lot.  In fact, it directly contradicts your
   tr> claims.  Please note the following quote:
   tr> 
   tr> "If undernourished women have fewer children than well-nourished ones
   tr> who do not practice contraceptions, why is there such a rapid
   tr> population growth in the developing countries?  The paradox is
   tr> explained by the fact that the death rate in these countries has been
   tr> reduced by mondern public health measures while the birthrate has
   tr> remained the same"
   tr>
   tr> This is exactly the case with deer.  In areas without "handouts and
   tr> crops", the fat content will lower the fertility of the herd.
   tr> However, by removing predators, we have altered the "death rate".  The
   tr> population will explode.

   You're grasping at straws.

You can't admit you're wrong.

   When you say the population will "explode", are you referring to 
   a two-fold increase?  a four-fold increase?  an eight-fold 
   increase?  If the fertility has been lowered when the population 
   is at 1N, thanks to the impact of diminished caloric intake on 
   adipose tissue, it seems to me that it would be pretty tough for 
   the deer population to continue to "explode" to 2N, or 4N, or 8N.  
   If you disagree, please explain.  

The caloric intake was "perfect" for 1N.  The reduced fertility won't
even start taking effect until 2N or 4N.  So, the population would
continue to grow at least past that point.

   tr> I am disappointed in you Russell.  I think you just kept providing the
   tr> source and hoping no one would actually read it.  I read it and I
   tr> don't think it supports your claim that populations can regulate
   tr> themselves without predation.  Please provides more documentation or
   tr> an example to support your assertations, or retract your statements.

   Would you be willing to abandon your hunting practices if/when we 
   can thoroughly prove that the cessation of hunting would not 
   culminate in starvation?  If not, then the issue at stake isn't 
   really an argument as far as you're concerned but an "excuse" or
   "rationale".  As such, your displays of indignation seem rather 
   transparent to me.  

I have said many times that I do not hunt to thin the herd.  I hunt
for _me_ (and to a lesser extent, my family).  I am happy the herd is
healthier but that is not why I hunt.  My sole reason for continuing
with this thread is to correct inacuracies and errors in your posts.

   In any case, we disagree.  I think the Frisch article does 
   support the notion that populations can regulate without 
   predation...  provided, of course, that we're dealing with 
   non-migratory animals living in habitats that aren't subjected
   to ongoing, destabilizing influences, such as forest management
   practices that increase the calories available in summer without 
   increasing the calories available in winter.  

   I'll be happy to post additional evidence later on to more firmly 
   establish the relationship between fat and fertility.   In addition,
   I'd like to answer the following questions:

No, Russell.  The ball is in your court.  You have failed to provide
any evidence populations can control their populations.  Please
provide such evidence.  If the answers to your questions would provide
such evidence, give them.  I do not have the time to do your research
for you.

Also, if you want to talk about forest management strategies, I'd be
happy to discuss them.  But, let's not get side-tracked from the issue
at hand.

tim
--
    ...  Then they came for me,
	   and by that time there was no one
	     left to speak up for me. (Rev. Martin Niemoller, 1945)

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