23-7-1986
Dear
Bill,
Many
thanks for the two editions on Chicken
Bone Recoveries, the supplement contains many interesting ideas!
I’d
be very grateful if I can get Somes’ papers on blue eggs, when you have the
time to photocopy them. I couldn’t find the reference on blue egg layers in
Asia at home, but I’ll add it on at the end of this letter tonight, in
Geelong, before I post it (the book in Geelong).
I
don’t know whether it has much information, but at least it may lead to an
original article referring to Asian blue egg layers.
If
you hear more on Prof Cawley’s Araucana book, I’ll be very interested in
that also.
Oh,
yes, you’re welcome to use my letter as you like, though these isn’t much
new or unusual in it!
I’ll
be reading and rereading the Supplement
for a while, absorbing parts of interest, but two things particularly caught
my attention.
First,
as a taxonomist (this is the study of classifying living things) I must say
that the article on Gallus europaeus
is very suspect! The coracoid bone is a very minor one to be basing a whole
new species on! In addition, this one bone was only compared to 5
corresponding examples of Gallus gallus
and that doesn’t prove a lot! Now, I haven’t seen the bone itself, and
birds aren’t my field, but parts of this supposedly different bone are
missing, and these are supposed to be among the most distinctive parts.
However my comments don’t necessarily mean a lot. I’m only going on that
was written. Even so, there are a lot of new names made up every year or very
flimsy evidence, and all they generally cause is confusion and argument until
they’re rejected, and unless more solid evidence turns up, Gallus
europaeus will be a has-been
very quickly. Which is not to say that there is no such bird, but only that
this evidence seems very weak. I certainly wouldn’t put it more strongly
until I see the original paper.
The
most interesting part of the supplement was the suggestion that Araucanas may
be a grouse/domestic fowl hybrid! It certainly has some potential for
explaining a number of unusual features.
The
comments on ear tufts on pp. 19-20 seem relevant here.
Working
with fishes, I have often found, or read about, hybrids which fail to develop
post a certain stage. What usually happens when a lethal trait shows itself is
that the combination of two different, but poorly matched, genes (from the two
different species) do not from a balanced
gene which will do what it should, because they are incompatible. When the
creature reaches a stage when the incompatible gene combination is needed, it
fails, and death or physiological damage may result. Thus, some hybrids always
die at a set stage of development, they are lacking genes capable of doing the
job they should.
Not
all hybrids are lethal incompatible genes may show themselves at all stages of
development. Some may prevent the hybrid from even occurring in the first
place, while others may not be lethal or even harmful, but may make the hybrid
sterile.
Somes
refers to ear tufting in Araucanas as the heterozygous expression of a single
dominant autosomal gene. In other words, the two parts of the gene must be of
two different kinds for it to work. If the gene is homozygous (has both parts
the same) the gene is a complete prenatal lethal, i.e. no eggs will hatch!
He
also states that even the heterozygous combination in lethal in 20% of cases,
however, prenatal death occurs for a number of reasons in poultry, 20% not
being so uncommon, so this may not be relevant.
This
could possibly be explained by some unusual hybrid gene, requiring two
different forms of itself to be united before they can work properly as one.
However, it could also be the result of inbreeding (e.g. a lethal recessive).
I’ll
try getting hold of the relevant paper, and see if anything is certainly
intriguing!
Thanks
again for the two booklets. I’ll be thinking and reconsidering a whole lot
of information, and I’ll be in touch again soon.
If
I can find the reference Sauer mentions Asian blue egg layers in, I’ll write
it below.
All
the best,
C.O.Sauer,
Agricultural Origins and Dispersals, (p.58?), 1952