NetNews Usenet Archive 1993 #3/NN_1993_3.iso/spool/bit/listserv/csgl/2317

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From Greg Williams (930228)

1. Quoting Durward L. Allen (Professor of Wildlife Biology, Purdue
University), WOLVES OF MINONG [ISLE ROYALE, IN LAKE SUPERIOR]: THEIR
VITAL ROLE IN A WILD COMMUNITY, Houghton Mifflin, Boston, 1979:

321-323, 325-326 - "Sometimes we see animals doing things that spell
individual destruction. How do they get away with it? How could THIS
have survival value? If we pause to reflect, these are not questions
to be asked of individuals, but of species. Maybe it was for the
common good that the individual did die. Then too, everything dies; it
is only a question of when.
  It can be difficult also to explain why animals do certain things
that simply seem to be wasted effort. A stumper that often challenged
me is why the beaver girdles or half cuts many food trees without
finishing the job. He spends untold hours and energy chiseling away
and gets nothing at once to show for it. Where lies the incentive?
  I may have got a bit more insight into this situation on a hiking
trip of about 40 miles over the center portion of the island in early
May 1976.... I found many aspen windfalls blocking the trails that
spring...
  Around beaver ponds girdled aspens and birches were budding out and
the sap was running. The trees were still alive, even though some of
the girdling was from the previous summer....
  High winds had blown down the partially cut trees far and wide. I
began to realize that the half-job of the beaver was effective after
all. With a minimum expenditure of energy, the animal now had fallen
aspens to feed upon, and so did the moose and hare. The removal or
killing of large trees would open up the stands and accelerate plant
succession....
  It is a profitable intellectual enterprise to ask why things happen
and to study the alternatives; good logic may take several directions.
Cutting or half-cutting trees could sometimes represent a wasted
effort that has no benefit for the individual beaver. However, this
animal does not work by judgment, but by a compulsive innate behavior
pattern. He must cut trees because they are there, and in the long run
it gets beavers ahead, even though any one piece of business could be
a loser.
  It came to me vividly how animals do these things on an evening of
beaver watching... A beaver flooding had inundated the trail.. and I
crossed on the dam. I climbed the low ridge ahead just before
sundown....
  Then I went back to the pond for some late-evening watching. Earlier
I had noticed that a dead aspen stub had been freshly girdled by a
beaver. The wood seemed hard, but the stub was limbless and so far
gone it had broken off 20 feet up. Strewn about was better material
for a dam; the stub was not food; why cut it?...
  I mused at length on why a beaver would spend its energy on that
useless stub. The explanation may be an extension of the half-cutting
idea proposed earlier. The cutting of anything and everything is
generalized behavior that provides for individual and colony survival.
But it goes beyond that; it is community service. It contributes to
the pond-meadow-forest rotation that brings diversity to bottomlands
and benefits all living things in this association. The beaver is a
good ecological citizen.
  In this vein, what seems like wasted effort is not wasted in the
long run. For the beaver to survive, its life community must survive.
In these self-operating organizations of living things nothing
actually is wasted: not substance, not energy....
  To follow through, one must assume the existence of logical reasons
for everything he sees. Some reasons seem obvious; many more are a
mystery. All about us are adaptations we take for granted, but which
might be understood if we looked long enough.
  For example, how does one explain the unique bark of the birch; the
bark that, once peeled, will never grow back? It became a magnificent
cultural material for the Indian. In the forest, that tough thin bark
lasts for many years after the tree is dead. Why?
  Again, we may be dealing with community benefits. When beavers
girdle an old birch, or when a stand of trees is flooded behind a new
dam, the trees are killed and the largely limbless stubs continue to
stand. The birches will be there after other species have rotted away,
protruding from the water for decades. The wood softens, and
woodpeckers dig out nesting cavities....
  These cavities become secondhand nesting places... Some of them
become large with use... The wood will get so weak the stub eventually
falls, but the old tree has served for a long time....
  Amid the complexities of nature we can ask endless questions, both
practical and academic, that could be profitable to explore. For now,
perhaps, they have value in pointing up our ignorance. They seem to
say, keep some country in its natural state so we will have time to
learn what it is really like. Our questions and ignorance suggest a
go-slow policy in destroying anything irreplacveable.
  In all realism, it is not our nature to slow down on anything. As
the master species, we are hard at it. I lie in my tent and listen to
the singing mosquitos. How great it would be, I think, to be an all-
powerful benevolent biological dictator for just a short spell. What
good one could do.
  Then it occurs to me that someone said mosquitos pollinate the
habenaria orchids."

2. I have never succeeded in getting Kentucky biologists interested in
pursuing the provocative findings of computer simulations by David
Sloan Wilson, as published in "Evolution on the Level of Communities,"
SCIENCE 192, 1976, 1358-1360, and THE NATURAL SELECTION OF POPULATIONS
AND COMMUNITIES, Benjamin Cummins, Menlo Park, 1980 (especially
Chapter 6. Multilevel Evolution). I'd very much like to see more work
on this; the situation here is analogous to the Veblening of economics
(getting away from "homogeneous [and isolated, almost as monads]
globules of desire" as models of individuals), which, unfortunately,
never happened (but might still -- Bill Williams is working on his
book about PCT foundations for economics again). Gary, I'd be
interested in reactions of U. of Illinois evolutionary biologists to
these references. Also, I think the sort of connections Wilson is
considering might prove to be important in reorganization processes.
Basically, Wilson explored the upshot of cases where organism A
increases the probability of survival of organism B (perhaps a
different species than A), which (perhaps through a complicated chain)
increases the probability of survival of organism A. The abstract of
Sloan's SCIENCE paper is as follows:

  "According to traditional models, natural selection is largely
insensitive to an organism's effect on its community. Effects on the
community at large cannot feed back differentially to the organisms
that cause them, and, hence, cannot lead to the differential fitness
of the organisms. However, if a spatial variation exists in community
composition, organisms do differentially feel their own effects on the
community, and this leads to a form of evolution on the community
level. Without violating the principle of individual selection, the
concept of an organism that exists for the 'function' it performs in
its community may be valid in some cases."

As ever,

Greg