on wing patterns

[Jeff Oliver]

>In the very broadest sense David is correct. There can absolutely be no
>"variation" in wing patterns without genetic differences. 

Doesn't this fly in the face of the notion of phenotypic plasticity?
Variation need not have a genetic component to it.  Heat shock proteins,
responding differently at different temperatures, demonstrate variation in
phenotype without any genotypic variation.  Freakish Nymphalis antiopa wing
patterns may be due to the different enviromental conditions (normal vs.
cold) rather than any underlying genetic differences. 

>The most common way
>we see this is the long employed "trick" of breeders to subject about ready
>to emerge butterfly pupae to sudden cold. All kinds of aberrations are
>produced this way because it alters (customizes) the genetic mapping.

The genes don't change at all, nor does their location in the genome.

>Ecotypes are not subspecies. If "subspecies" (A) from the California
>desert, when reared in the environment and on the host of a sister
>"subspecies" (B) from the San Francisco Bay area, produces adults whose
>phenotype is basically identical to subspecies (B) then (A) is not a
>subspecies. It is an ecotype - no matter how massive the range and
>consistent the pattern of the desert population is. The same holds true for
>altitudinal "forms".

However, cannalization can work the opposite way of phenotypic plasticity:
different genotypes can produce the same (or similar) phenotypes under the
same environmental conditions.  Just 'cause they look the same, doesn't mean
there's no genetic difference between the two.  So, if there's a genetic
difference between spp. (A) and (B) above, subspecies designation may not be
such a bad idea.

Genetic variation can exist in places other than wing patterns, as evident
in the very genetically distinct E. comyntas and E. amyntula (anyone who's
been in sites of sympatry knows that the wing morphology can often be
useless in distinguishing these two species).  

Jeff Oliver
jeffrey.oliver at colorado.edu


 
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