Tarzet
05-21-03, 05:58 AM
This is some info a customer sent me. It is long...but interesting. I would also like to know what others thought of this?
This information is something that Sharon found on the Yahoo's Pogona Group, the oldest dragon forum on the Internet. This was of GREAT importance to Annie and I, because of TAJ. Taj had a marking that we have commented on since the very day we did her rescue....a broken ring on the wider part of her upper tail. You will understand why this is important when you have finished reading this material. PLEASE consider this when you choose a dragon! Kathryn Tosney is one of the world's most noted experts on Australian Bearded Dragons and her work, along with that of Alta Brewer and Melissa Kaplan in based on good, solid information. "Kathryn had theorized about the tail rings on Pogonas as relative to
inbreeding and/or overall health. Someone had started keeping some record somewhere of tail ring patterns, looking for where the pattern break occurs (close to the body vs. farther down the tail). Taj's was closer to her body. Without going into the whole thing, I'm wondering whether any conclusions were able to be drawn, or whether this is an ongoing project? And does it have applications if one is considering acquiring a beardie for one's son, who really, really wants one and will even learn to deal with superworms? Scientific minds want to know."
"The theory refers to the pattern of rings (the narrow light bands) on
the tail. I class the ring as the narrow white band. Some dragons
have no breaks in pattern, and the rings are uninterrupted right to
the tail tip. Many dragons have an interruption in pattern at about
the 5th or 6th ring on the tail, counting from the vent. Some have
more than one interruption in pattern along the length.
The hypothesis is that numbers and positions of irregularities can
indicate inbreeding. Note, that the hypothesis doesn't predict health
of an individual dragon, but is instead may indicate the degree of
inbreeding (so that the animal may have more homozygous genes which,
depending on the genes, can be a problem).
Inbreeding usually doesn't produce obvious birth defects in the first
generation, but it does have other bad effects. In many many species,
if siblings are mated, then the progeny show immediate effects:the
fertility diminishes, the hatching rate is lowered (due to early
lethalities; many die early in development), survival through infant
and adolescence is lower and the adult size diminishes (possibly
explaining the general reduction in dragon size over the last
decade). Those effects are seen in the first generation. In later
generations, birth defects also become more common.
I have begun to suspect that that nice long distance between the tail
base and the pattern break might be an indicator of outbreeding, or
of good genetic health and general robustness. I think that because
some "sickly" hatchlings seem to have a pattern break much closer up
the tail to the body, and fail to thrive. Some adults who have been
beset by illnesses also have that pattern, suggesting they are less
robust than others and need more attention to keep healthy. I
gathered the most data at three yearly trips to the International
Reptile Breeder's Exposition in Daytona. I examined a lot of dragons,
and found that incidence of irregularities in the tail pattern
correlated roughly with apparent inbreeding. That is, there were more
pattern irregularities in the brightly colored dragons (hence more
inbred--you have to inbreed for awhile to get such colors "fixed" in
a breeding line) than in the regular dragons. Indeed, I could
practically chart the degree of irregularities with the price of the
dragon-- $100, 90% of the dragons lack irregularities; $200, 50-60%
have irregularities; $300 or more, 90% have irregularities.... Not
that the more inbred dragons were sickly, but that the pattern
appeared to correlate with inbreeding, which could pose possible
problems.
For some of the breeders at Daytona, the brightly colored ones were
showing fewer pattern anomalies last year. I suspect that these
breeders are using careful outbreeding practices: they are retaining
the color gene in their breeding stock, while successfully breeding
in genetic diversity. Dragons from some other breeders do not show
these characteristics.
We do need visible markers for inbreeding... so, tail pattern may be
one, that works for populations. It is certainly not a thoroughly
tested hypothesis, and is still capable of being disproved. More
important: It is unlikely to be a good marker for health on an
individual basis. If you pick a dragon that has irregularities in his
tail pattern, that does NOT mean he will be sickly or die.
Of course, if I were choosing a new dragon for myself, I would choose
an alert, plump dragon, larger than most of his clutchmates (if he is
a baby)...and all else being equal, having a good symmetrical pattern
with few interruptions in the tail pattern.
But then, that is just me.
I would still be interested in hearing from people who have paid
attention to tail patterns and dragon health.
This information is something that Sharon found on the Yahoo's Pogona Group, the oldest dragon forum on the Internet. This was of GREAT importance to Annie and I, because of TAJ. Taj had a marking that we have commented on since the very day we did her rescue....a broken ring on the wider part of her upper tail. You will understand why this is important when you have finished reading this material. PLEASE consider this when you choose a dragon! Kathryn Tosney is one of the world's most noted experts on Australian Bearded Dragons and her work, along with that of Alta Brewer and Melissa Kaplan in based on good, solid information. "Kathryn had theorized about the tail rings on Pogonas as relative to
inbreeding and/or overall health. Someone had started keeping some record somewhere of tail ring patterns, looking for where the pattern break occurs (close to the body vs. farther down the tail). Taj's was closer to her body. Without going into the whole thing, I'm wondering whether any conclusions were able to be drawn, or whether this is an ongoing project? And does it have applications if one is considering acquiring a beardie for one's son, who really, really wants one and will even learn to deal with superworms? Scientific minds want to know."
"The theory refers to the pattern of rings (the narrow light bands) on
the tail. I class the ring as the narrow white band. Some dragons
have no breaks in pattern, and the rings are uninterrupted right to
the tail tip. Many dragons have an interruption in pattern at about
the 5th or 6th ring on the tail, counting from the vent. Some have
more than one interruption in pattern along the length.
The hypothesis is that numbers and positions of irregularities can
indicate inbreeding. Note, that the hypothesis doesn't predict health
of an individual dragon, but is instead may indicate the degree of
inbreeding (so that the animal may have more homozygous genes which,
depending on the genes, can be a problem).
Inbreeding usually doesn't produce obvious birth defects in the first
generation, but it does have other bad effects. In many many species,
if siblings are mated, then the progeny show immediate effects:the
fertility diminishes, the hatching rate is lowered (due to early
lethalities; many die early in development), survival through infant
and adolescence is lower and the adult size diminishes (possibly
explaining the general reduction in dragon size over the last
decade). Those effects are seen in the first generation. In later
generations, birth defects also become more common.
I have begun to suspect that that nice long distance between the tail
base and the pattern break might be an indicator of outbreeding, or
of good genetic health and general robustness. I think that because
some "sickly" hatchlings seem to have a pattern break much closer up
the tail to the body, and fail to thrive. Some adults who have been
beset by illnesses also have that pattern, suggesting they are less
robust than others and need more attention to keep healthy. I
gathered the most data at three yearly trips to the International
Reptile Breeder's Exposition in Daytona. I examined a lot of dragons,
and found that incidence of irregularities in the tail pattern
correlated roughly with apparent inbreeding. That is, there were more
pattern irregularities in the brightly colored dragons (hence more
inbred--you have to inbreed for awhile to get such colors "fixed" in
a breeding line) than in the regular dragons. Indeed, I could
practically chart the degree of irregularities with the price of the
dragon-- $100, 90% of the dragons lack irregularities; $200, 50-60%
have irregularities; $300 or more, 90% have irregularities.... Not
that the more inbred dragons were sickly, but that the pattern
appeared to correlate with inbreeding, which could pose possible
problems.
For some of the breeders at Daytona, the brightly colored ones were
showing fewer pattern anomalies last year. I suspect that these
breeders are using careful outbreeding practices: they are retaining
the color gene in their breeding stock, while successfully breeding
in genetic diversity. Dragons from some other breeders do not show
these characteristics.
We do need visible markers for inbreeding... so, tail pattern may be
one, that works for populations. It is certainly not a thoroughly
tested hypothesis, and is still capable of being disproved. More
important: It is unlikely to be a good marker for health on an
individual basis. If you pick a dragon that has irregularities in his
tail pattern, that does NOT mean he will be sickly or die.
Of course, if I were choosing a new dragon for myself, I would choose
an alert, plump dragon, larger than most of his clutchmates (if he is
a baby)...and all else being equal, having a good symmetrical pattern
with few interruptions in the tail pattern.
But then, that is just me.
I would still be interested in hearing from people who have paid
attention to tail patterns and dragon health.