Posted by:
b1eagar
at Tue Sep 6 16:27:08 2005 [ Email Message ] [ Show All Posts by b1eagar ]
The western subspecies of T. sirtalis were originally based
on few specimens from a limited geographic area. They thus didn't
show a lot of variation between what were thought to be definative
subspecies. As more specimens have been collected over a wider
geographic area over the last century, the rules seperating these
subspecies have gotten weeker. Thus,
you have subspecies described at their extremes and not at what is
normal accross their range. I have seen Valley garters from
Utah, Idaho and Oregon with red heads. Red headedness is not
an indicator of anything more than a greater amount of red in
any given population of these animals. I have seen california
red sided garters that had very little red on their heads as well
despite the fact that they were within populations of individuals
with typical red heads.
As far as integration goes, there is definately integration taking
place amongst the western subspecies. In the Columbia river
gorge, you can find both red spotted garters and valley garters
and some that resemble both. Likewise, within the range of the
pudget sound garters you can find individuals wich look like
pudget sound garters or like valley's or like neither (ie. having
no blue or red coloration). Likewise, in the range of the
california red sided garters you can find some that resemble
San Fransisco garters. I have heard of normal looking
WC California red sided garters giving birth to San Fransisco looking
babies before.
In my opinion all the subspecies of western Sirtalis should be
combined into one. All we are seeing are color variants in different
geographic areas. Not true subspecies. The logic which has
made all of these different subspecies would also make the
melanistic eastern garters a different subspecies.
I'm sure that one could come up with a San Fransico looking
Western Sirtalis through selective breeding of high red individuals.
There are also populations of Valley garters that look pretty
much exactly like red sided garter snakes from the midwest.
The taxonomic status of the Utah/Idaho/Wyoming population has been the subject
of much debate amongst scientists in the past because of this.
It is really only the continental divide barier that has placed
some of these populations in the Valley Garter category.
This is a much better argument than external appearences.
Subspecies are best defined by where they live in conjunction
with DNA and morphological differences and not by color variations.
As far as Oregon redspotted garters belly coloration goes,
I have seen blue, yellow, and black bellied individuals all
within the same wild populations in Oregon. Belly coloration
is certainly not a definative trait. However, I think the
best single characteristic for defining true Oregon
red-spotted garters is that they should be void of the side stripes.
>>I am interested in learning more about this. I have seen alleged concinnus with the lateral striping but I have not been able to find any fitchi with red on their heads like this. All of the information I have found states that fitchi do not have red heads, that this is a definitive trait. I will continue searching and comparing. Where are your red headed Valleys originating? Perhaps it is a more area specific morph. I am also not aware of any places where intergradations are known to occur.
>>-----
>>Randy Hallman
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RE: Oregon Red Spot, or Red Sided? *pics* - b1eagar, Tue Sep 6 16:27:08 2005