Chimera (kī-mîr′
ə, kĭ-) n. A hybrid, female creature
composed of part lion, part goat and part snake (Greek mythology); any
fictitious monster consisting of disparate elements; a harbinger of doom.
T
he fearsome fire-breathing chimera of
antiquity first appeared in Homer’s Iliad, and
apparently tormented the region of Lycia
until it was ultimately dispatched with a lump of
molten lead. The origin of this legend may be traced
to a series of vents in a hillside in southern Turkey
that to the present day emit burning plumes of
methane, and were important landmarks for ancient
sailors. Later, the title of chimera became applied to
any fictitious animal composed of a mismatch of
body parts. More recently, geneticists appropriated
the term to describe a rare state in which a single
organism contains cells of different genotypes, the
expression of which may give rise to a heteroge-
nous appearance. The most familiar example to
anyone with an interest in herpetology is the
‘Paradox’ albino - but these stunning, highly-prized
animals could hardly be described as monsters!
This article was inspired by the recent birth of a
beautiful, brand new Paradox albino Spotted Python
(Antaresia maculosa). iHerp Australia then
canvassed some of the handful of breeders around
the country who have
been lucky enough to
produce and work with
Paradox snakes. The
more research we did,
the bigger the story
grew, assuming almost
epic proportions - as did
our collection of incredible photos - but becoming
increasingly fascinating in the process. Before
introducing some of these amazing creatures, it is
worth briefly examining the nature and inheritance
of this condition, which is often shrouded in as much
mystery as the original chimera of the Iliad!
should not occur. How does this happen? One
explanation is that Paradox albinos are true genetic
chimeras that result from the fusion of two different
zygotes into one organism. So they contain both
normal and albino genotypes, which create a
‘patchwork’ phenotype. Depending on which
genotype creates the gonads, or sex organs, it is
therefore possible that Paradox albinos will produce
gametes containing either the recessive albino
allele, or the ‘normal’ one. In other words, they are
capable of producing albino or normal-looking
progeny. Since it is due to the chance merging of
two fertilised eggs, the Paradox condition created
under these circumstances is not genetically
heritable.
A small number of Paradox albino Darwin Carpet
Pythons have been around for a few years here in
Australia, and in late 2016 K Brothers Pythons (Troy
and Denver Kuligowski) produced a fascinating
YouTube video in association with Morelia Magic
(Wayne and Deb Larks) that examined the issue of
a pairing of two Paradox albino specimens. Similar
numbers of albino and
het hatchlings were
produced, as may be
expected from a
conventional albino to
het pairing, thereby
supporting the notion
that this form of
Paradox is a chimera originating from the fusion of
two eggs (you can view the video here: https://
www.youtube.com/watch?v=jFNrnlk6ogM).
.
However, some pairings tend to throw the odd
Paradox on a regular basis, and breeders in this
country and overseas (the latter principally working
with Paradox albino Ball Pythons and sand boas)
have noticed a degree of heritability. This may be
explained by an alternative theory for the creation of
a Paradox phenotype; spontaneous loss or gain of
function caused by mutation of the albino/wild-type
alleles. Sounds complicated, but let’s look at a
couple of simple examples. Take an embryo that is
het for albino; if the wild-type allele is rendered
non-functional (or deleted) in a single cell early in
development, all cells derived from this cell will
behave as albino, resulting in a patchy appearance.
A similar effect could be produced in a homozygous
albino by an albino allele that ‘reverted’ back to wild
type (gain of function). If the gene concerned is
inherently unstable, this would account for some
heritablility. This is an example of a phenomenon
that geneticists refer to as ‘mosaicism’, in which
different genotypes exist in a single organism due to
early mutation.
‘A Paradox albino exhibits areas of
melanin deposition that simply
should not occur .’
Albinism (derived from the Latin albus for ‘white’) is
a simple recessive trait, found in all types of
vertebrates, in which melanin (the black/brown
pigment in skin and other tissues) is either not
produced, or prevented from gaining access to the
chromatophores. In mammals, which possess only
a single type of pigment-bearing cell, this results in
an all-white phenotype with pinkish-looking eyes.
Reptiles, however, have additional chromatophores
containing red and yellow pigments, as well as
deposits of purine crystals that reflect light and may
create an iridescent effect. Therefore, albino reptiles
will not necessarily appear pure white, although
they will not possess dark eyes.
A paradox is a contradiction that should not
normally exist, and thus a Paradox albino is an
albino animal that exhibits areas of melanin
deposition that, under normal circumstances, simply