> This person implied that the genetics explanations used the term 'look normal'
> to refer to the dominant colour in the crosses. Normal, could be the wild type
> colours, or whichever was more dominant of the two colours being crossed. More
> dominant? Got me thinking.
THe problem is that most simple explanations talk about a single mutation of
a single gene, so there are only two alleles, the mutant form and the original
form, traditionally called 'wild-type'. Like anything in biology, the real
world is messier. While there can be multiple variant alleles of a single
gene, there are usually multiple genes controlling traits like skin color
and pattern in a lizard.
Dominant vs recessive applies only to the alleles of a particular gene.
There's another concept called epistasis. This means that the effect of
a mutation in one gene prevents another gene from expressing its phenotype.
Let's do this in mice, since leo genetics are not that well worked out.
All albino mice have white fur and red eyes. THey may also have the genes
for other coat colors and patterns, like piebald, black, etc., but because
they are unable to produce any dark pigment at all, you have no way of
knowing what other coat color traits they have, except by breeding experiments.
Similarly, white coat color in cats is a simple dominant, epistatic to all
other coat colors, and unrelated to white spotting. So you can't tell if
a white cat has genes for white spots unless you do breeding experiments
(or know a lot about its family tree). You also don't know if it's "really"
a tabby or black or gray or marmelade, either, but you can tell by breeding
experiments which alleles of which genes it carries.
> Don't laugh, but .... according to what I'd been told, if you crossed, as an
> example, a normal and albino, the hets would look normal, since it's dominant
> over albino. No problems there.
Right, but it might be less confusing if they said 'albino' and 'non-albino'.
> But, taking 'recessive' traits like albino and
> patternless, you'd get hets that look patternless, since according to this
> source, patternless is dominant over albino. The 'look normal' hets would in
> this case be patternless carrying albino genes.
Here's where your 'expert' heads off into left field. As far as I know,
albino and patternless are alleles of different genes, and they assort
independently. Assuming there are no patternless geckos in the ancestry
of the albino, the albino has two 'normal' or 'wild-type' or 'non-patternless'
alleles for the patternless gene. Ditto, if the patternless animal has no
albinos in its ancestry, it has two 'normal' or 'wild-type' or 'non-albino'
alleles for the albino gene. So when you cross them, the offspring each
get one allele for albino from one parent and one allele for non-albino
from the other parent. The also get one allele for patternless from one
parent, and one allele for non-patternless from the other parent. So they
are heterozygous for each trait, and since both traits are recessive and
they have a normal allele for each trait, the recessive traits won't show.
What they actually look like, other than not-albino and not-patternless,
depends on the rest of their genes.
> What really got me suspicious
> was the suggestion that 'two equally recessive' traits (whatever that term
> means), would fight it out. The topper was that in this case, blizzard and
> albino, both being 'equally recessive', the daughters would be whatever the
> mother is, the sons take after father, but all would carry the other parent's
> genes. Once I heard that, I just knew something wasn't right.
Oh, yeah, in an animal that has its sex determined by the temperature days
or weeks after fertilization, this is a dead giveaway that the speaker is
either seriously confused or seriously bullshitting.
> This expert also said that all the normal looking hets I'd seen had to have been
> normal X somethings, to have the offspring with normal colours. Albino X
> patternless would have been patternless coloured hets.
These two traits should behave independently, so if you cross your albino
x patternless to an albino, you'll get half albino and half non-albino.
Half of the offspring will also be het for patternless, but you won't know
which half. DItto if you cross the albino x patternless to a patternless,
you'll get half patternless and half non-patternless. Half of these offspring
will be het for albino, but again, you won't know which. If you cross two
albino x patternless to each other, you'll get the classic 9:3:3:1 ratio -
on average 9 of 16 will appear neither albino nor patternless, although
some will be het for one, the other, or both; 3 will be albino and may be
het for patternless; 3 will be patternless and may be het for albino; and
one will be both albino and patternless - you may not be able to distinguish
this from albino.
It's a lot easier if you use symbols and Punnett squares. Let's use A and a
for the albino trait and P and p for patternless. A is the non-albino or
normal or wild-type allele for the albino gene and a is the albino allele.
Similarly, P is the normal allele for patternless and p is the patternless
allele. It's a convention to use capital letters for the dominant allele
and small letters for the recessive allele.
So your albino gecko that has no patternless in its ancestry has the formula
aaPP, and the patternless that has no albinos in its ancestry is AApp. When
you cross them, all the offspring are AaPp. They don't show either albinism
or patternlessness, but they are heterozygous for both traits. These geckos
can produce gametes (eggs or sperm) of four types: aP AP ap Ap. If you cross
one to its albino parent, you get:
aP AP ap Ap
aP aaPP AaPP aaPp AaPp
i.e. half are albino (aa) and half are heterozygous for albino (Aa). Half
of each group is also het for patternless (Pp) and half isn't (PP) but you
can't tell which without further breeding experiments. The cross back to
the patternless parent is left as an exercise for the reader.
If you cross two of these AaPp animals, you get:
aP AP ap Ap
aP aaPP AaPP aaPp AaPp
AP AaPP AAPP AaPp AAPp
ap aaPp AaPp aapp Aapp
Ap AaPp AAPp Aapp AApp
You can pick out the 9 of 16 possibilities that have both at least one A
allele and one P allele, these are the 'normal' phenotypes. There are 4
of 16 that are aa, and these geckos will be albino independent of whether they
have one, two or no P genes, because albinism is epistatic to patternlessness
(ideally). That is, you can't distinguish an albino that is homozygous for
patternlessness from one that isn't. The remaining 3 of 16 have at least
one A allele and 2 p alleles, so they will be patternless. 2 of these 3
are also het for albino.
Btw, if any of you have followed this far and are still confused, get an
introductory biology text for an explanation by someone who does explanations
for a living. It's all the same, geckos or peas or fruitflies.
> Live and learn. huh?
Gosh, I hope so! (But we can't always count on it...)
> > That's how you might get a het for
> > patternless/blazing/avocado/samurai/stapler leopard gecko :)
>
>Sounds like you're describing a vibrant green coloured patternless 'hot female'
>who glues her eggs to the nesting box.
With superglue!
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