stelenes at pobox.com
Sun Apr 12 13:13:45 EDT 1998
Kenelm Philip wrote:
> Pierre le Roux said: "This would mean that the predators actually
> determine mimicry!"
> Was this presented as being a new idea? It was my understanding
> that no other explanation consistent with Darwinian ideas had ever
> turned up, for either Muellerian or Batesian mimicry. the mimic
> 'chooses' to mimic the model (!), which seems to me unbelievable. :-)
> Or have I missed something here?
There is a complication (see next Paragraph) and an interesting point to make
on "choice" of the mimic (further down message), although I would be equally
surprised if Kenelm is missing anything as it relates to the scientific
definitions of mimicry, which exclude camouflage.
Clearly, predation pressures influence the evolution and refinement of all
patterns, which by basic theory, may be driven by protection against
preditors. The complication in mimicry could arise when recognition of mates
is compromised, in which case a visual compromise might evolve. This
"choice" to DIFFER SOMEWHAT might be "driven" by the mimic, or even the
model, due to its "interest" in propogation.
In an even more general philosophical sense, why do viceroys look like
Milkweed butterflies? Is it the really best model for them over time? Why
not like pipevine swallowtails? The Red Spotted Purple is very closely
related to the Viceroy - right down to sharing hostplants - and looks like
the Pipevine swallowtail. Unless you live in Alaska, the ranges of the
RSPurple/White admiral complex are the same as the Viceroy!!
Sounds to me like a candidate for the following hypothesis: The ancestor of
both mimics was the same and, a combination of luck and predation pressure
basically caused two viable mimics. "Luck" could be interpreted as the
"choice" of the mimic's ancestor. But it may be less confusing to think that
the path from A (ancestor pattern viceroy) to B (Viceroy mimicing Danaus) is
part of the theory of evolution which includes chance mutations making
individuals more or less adaptable to continuously changing and interrelated
Similarly, chance could play a roll in a species' evolution of eyespots,
leaf, etc. patterns. Mimicry is not necessarily the only or best route to
go, but it sure can be a better "choice", whoever makes it, if you have an A
to B path to go down instead of doing nothing about it and becoming nutrition
for your preditor!
Douglas David Dawn
N. 25º 37.408'
W. 100º 22.003'
Altitude 910 meters
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