Hi Tim,



These are interesting hypotheses. I take your kinked spine observation to mean that you have experienced a spike in incubation temps and then experienced kinked babies? So you've at least experienced a coincidence, and maybe there's a correlation. Your experience breeding kinked snakes and not getting kinked babies is a powerful anecdotal argument against the inbreeding=kinked babies theory.



But I think your second example is a case of noting observable fact (many captive snakes aren't as big as the average adult sizes reported for wild-caught specimens in some books) but i don't see any particular reason that data leads to your conclusion or opinion: it could just as easily be that the authors of several books took only the larger wild caught specimens to be "adults", which would automatically bias the reported sizes:



Example: Suppose i catch 100 black rat snakes. They range from 15" to 7 feet. Maybe there are 20 in the 3 to 4 ft range, 20 in the 4-5 ft range, 20 in the 5-6 ft range. I might conclude the 4-6 footers are the adults, making the average adult around 5 feet. But maybe the 3-4 footers are reproductively mature too, and thus should also have been considered "adult". That changes the average of those three groups to 4 feet. See what i mean? (and remember that the older snakes get, the bigger they get, or at least i assume that's true in the wild, so if the snakes range from one to ten years old, the older ones would be bigger, and the sizes reported would be as much a function of age as of size. These reported "average sizes" should be viewed with considerable skepticism.



Lastly, the field guide data could just as readily lead to the conclusion that inbreeding is taking place to a harmful degree in the wild: The really big specimens for most ssp were reported, LONG, long ago--take that 8 1/2 foot black rat snake that's cited, for example. How come none like it have been reported since then? Is it merely a statistical aberrancy? A rare 20 or 25 year old specimen with particularly admirable genes--the Shaq or Yao Min (sp?) of obsoleta? Or is the absence of equally large black rats being found in the wild proof that (since the hypothesis is that it's INBREEDING that stunts sizes, inbreeding must be eliminating ALL the "big 'uns" in the wild now. (And, yes, some might argue there's been a lot of habitat destruction resulting in more inbreeding, but anyone who's flown over the southeast knows there is--relative to snake populations and movement--unlimited forest where those obsoleta lunkers could continue growing).



In the end, a thread like this one has as much to do with thinking imaginatively about what data MIGHT mean, what other factors might be involved, etc., as it has in interpreting some very modest data points.



peace

terry



>> I have two comments:

>>

>>1. Kinked spines most often occur when eggs are incubated at a steady temperature, then a spike in the incubation temperature happens (even if only for a day or two). I have bred "kinked" snakes and had babies come out normal, so I don't think it's genetic.

>>

>>2. Inbreeding snakes seems to prevent the animals from reaching their maximum size, as recorded from examples found in nature. The "average adult size" for several types of snakes common in the pet trade is significantly smaller than what those snake are are out in the wild, despite the captive snakes having a relatively constant supply of food.

>>

>>Of course, these are merely my opinions.

>>

>>Keep up the good work,

>>

>>Tim Spuckler

[ Show Entire Thread ]