Tiger Swallowtail-bilateral mutation on the winter 2007cover of "Butterfly Gardening"

[RWPJr]

Is it a "wysinnwyg" individual? (What you see is not necessarily
what you got.)

Two interpretations possibly among others including a combination
of both:

1. Both the right and left sides are female in which a gene
suppressing the black color was lost in the first embryonic division
and the left side shows the yellow female color. Test: was the
individual from the intergrading zone of P. canadensis and P. glaucus,
and was the individual an anatomically correct female which could have
mated and produced fertile offspring. If such is the case, the black
side may have resulted from hybridization between the two species and
loss of a gene hypothesized to occur in P. canadensis which suppresses
the black color.

2, The left side is male and the right side is female with
male claspers on the left and female genitalia on the right with an
anatomical division splitting the interior of the abdomen.
Explanation: the female is the heterogametic sex in butterflies and
the left side may have resulted from the loss of one of the two W
chromosomes in the female resulting in a spurious male phenotype W/O
and suppression of the black color, since the black/yellow dimorphism
is sex-limited, ie. expressed only in the male.

Respectable data would be helpful. I do wish the photographer
had had the presence of mind to get a shot of the abdomen under the
wings.

The right side does look a little strange in the attachment of
the right wings to the body and their relationship to the left side
almost as if the photograph were composite.

I have found only one bilateral gynandromorph in over 60 years
of butterflying and that was a male/female gypsy moth caught flying in
the Portland, Maine railroad station in 1943, 44 or 45.
In addition to the crisp difference in wing pattern, one half had a
feathery antenna of a male and the other half a naked hairlike antenna
of a female. It was an exciting find but now I regret my abysmal
ignorance and as a scientist wonder what I would have found, written,
and published if I had been in a state of development and in a lab and
had killed, dissected, and written a paper about my findings.
Nevertheless, the observation that the specimen was actually flying
and required some agility on my part to net as well as some
embarrassment to pursue in a crowded railroad station might be viewed
as a saving grace. I am sure W.J. Holland did not suffer more in his
pursuit of the magnificent Diana Fritillary past a girl's school in
his youth.

Roger Pease
Springfield, MA

[RWPJr]

Correction: I have revised paragraph 2. below to be consistent in
interpreting the female as the heterogametic sex.

2, The left side is male and the right side is female with male
claspers
on the left and female genitalia on the right with an
anatomical division splitting the interior of the abdomen.
Explanation:
the female is the heterogametic sex in butterflies and

the right side may have resulted from the loss of one of the two W
chromosomes in the male resulting in a spurious female phenotype W/O
and expression of the black color. The left side is male W/W and
carries the gene(s) for black but since black is a sex-limited trait
expressed
only in the female, the male side stays yellow. The male side might
be
expected to be functionally male but since the female side lacks the
Z
chromosome that side might be sterile.
Now if I had just tried to get eggs from the Gypsy Moth
gynandromorph
mentioned later on, I could have added to the question of fertility or
sterility
of the heterogametic side.
I took the Gypsy Moth specimen to a show and tell science class
in junior high school (fall of 1944 or 1945) in New Britain, CT.
Since any
mention of meiosis and the reduction divisions producing germ cells
was
omitted from the biology books we were using I can now understand why
the teacher was a little uptight but I gave a nice explanation in
terms of
mitotic cell division in the egg in which the genes determining sex
characteristics were lost in the first embryonic division in the
fertilized egg.
Fortunately, a gynandromorph of the Clouded Sulphur was illustrated
and
explained in Natural History at the time and gave an explanation.

Roger Pease
Springfield, MA