Re: Conspicuous Coloration and Poisonous Ingestion

Sat, 9 Sep 2006 13:40:08 -0400 (EDT), drosen0000@xxxxxxxxx wrote:

Poisonous frogs and other venomous animals often have bright
colors that make the animal clearly conspicuous. Animals that are
nonvenomous are seldom conspicuous. The usual explanation provided for
the conspicuous features is that conspicuous features have a fitness
value by alerting hungry animals that this is a venomous animal. I have
a question concerns the first steps in the evolution of the both
conspicuous color and venomous.

Consider the environment that existed before the conspicuous
coloration evolved in the frog. No frog predator has yet evolved to
recognize the correlation between conspicuous coloration and venom. The
frog population probably has a mixture of venomous and nonvenomous
frogs, as this is a perfectly plausible random variation. At the very
beginning of the evolutionary process, there is no correlation between
venomousity and conspicuousness. That is the definition of "random".

Where does the initial fitness value for either the conspicuous
coloration or venom come from? A frog once eaten is dead, whether or
not it is venomous or conspicuously colored. A conspicuous frog is
vulnerable to predation whether or not it is venomous. A frog predator
that eats a venomous frog is dead, whether or not it is conspicuously
colored. A frog predator that eats a nonvenomous frog is just as
satisfied with a conspicuous frog as with a no conspicuous frog. A frog
predator that eats a venomous frog is dead.

Note: I know that poisonous frogs get their poison from the
insects they eat. Some of the insects may in turn may get their poison
from the food the insects eat. However, this couldn't effect the
cdorrelation between coloration and venomosity. Could it?


The conspicuous colors are called "aposematic". The question you
raise is sometimes called "immediate advantage" and relates to
individual selection vs. group or kin selection. There are a number
of papers that deal with this issue. See, for example, "Notes on the
evolution of unpalatability in butterflies by means of individual
selection"., by L. Kassarov, at
http://www.doylegroup.harvard.edu/~carlo/JRL/37/PDF/37-071.pdf

Another source is "Aposematic coloration" by Mathieu Joron
http://zeldia.cap.ed.ac.uk/joron/joron02apo.pdf#search=%22aposematic%20%20color%20evolution%22

Both have bibliographies with more, or just google "aposematic
coloration".




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