Mimicry (was Re: lack of butterflies)

[Doug Yanega]

TDWolfe wrote:

>I'm sorry to be so ignorant, but...what is the difference between Mullerian and
>Batesian mimicry?

A matter of degree. Seriously. In conceptually "pure" Batesian mimicry, the
model is inedible/dangerous to some degree, and the mimic 100%
edible/harmless. In "pure" Mullerian mimicry, both model and mimic are
inedible to exactly the same degree.
        In reality, either situation is very unlikely, and almost all
mimicry systems will have one or two complications:
(1) if the mimics are not 100% edible/harmless - if they are *slightly*
distasteful, for example - then one is in a gray area as to whether they
are Batesian or Mullerian mimics! - likewise, Mullerian mimics are unlikely
to have exactly the same chemical profiles, therefore unlikely to really be
equally inedible - and if one is more inedible than the other(s), you've
got a situation that can in principle blend with the above. So, most REAL
systems are probably in the gray area between the two extremes. In
practice, most folks will err on the side of calling a system Mullerian if
they think the mimics are even a little bit unpalatable.
(2) most mimicry systems are subject to predation pressure from MORE than
one predator, and not all predators will have the same tastes. Predator A
may consider species X edible and species Y (which X resembles) inedible,
while predator B may consider Y *more* palatable than X, but still not like
to eat either, and predator C may find both to be edible. Is X or Y the
mimic? Is it a Batesian or Mullerian system?

Now extend this to a more realistic situation with dozens of potential
predators and 5 or more insects that resemble one another to various
degrees and have all sorts of different types and levels of physical or
chemical protection. See the problem?
        In the end, the classical definitions are just sort of a convenient
shorthand way of summarizing our limited knowledge of the real dynamics in
the system, which are complex and multidimensional. The concept is okay,
certainly, but in practice rather subjective and *very* simplistic.

Peace,

Doug Yanega    Depto. de Biologia Geral, Instituto de Ciencias Biologicas,
Univ. Fed. de Minas Gerais, Cx.P. 486, 30.161-970 Belo Horizonte, MG   BRAZIL
phone: 031-449-2579, fax: 031-441-5481  (from U.S., prefix 011-55)
                  http://www.icb.ufmg.br/~dyanega/
  "There are some enterprises in which a careful disorderliness
        is the true method" - Herman Melville, Moby Dick, Chap. 82