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Posted by zeteki on January 20, 2003 at 20:44:24:
In Reply to: Re: Opinions on crossing two different subspecies....Must Read! posted by glenn bartley on January 19, 2003 at 11:24:26:
:Zeteki,
:You brought up some good issues for discussion.
Thanks. You bring up some interesting points yourself.
:I forgive you,
Thanks again.
:but now I wonder: Did you say this because you believe I do not realize that difference, or was it because you felt someone else may not realize it after reading my post?
(snip)
: The question in my post about captive versus non-captive snakes was, in essence, why would one species interbreed with another species in captivity and not do the same in nature if the same two differing species encountered one another naturally?
I said it because it was germane to my point. Captivity is an important factor when discussing breeding preferences. As I stated before, captive animals do not have the myriad choices available to their wild counterparts. This applies to choices about hides, thermoregulation, prey stalking, and mate choice among many many other things. When "in the mood" a captive snake is forced to either mate with an individual it would not choose in the wild (a genetically undesirable individual), or not mate at all. The drive to reproduce is strong, as is the drive to produce healthy offspring. For this reason animals have developed elaborate mechanisms and rituals around mate selection. I really don't know what goes into mate selection for a snake, but I suspect that there is some degree of selection. My guess is that a snake given choices will most likely pick a mate that displays some sort of desirable traits (speed, size, etc.). A snake in captivity does not have these choices and picks the most appropriate mate it can find. Sometimes this may mean a snake of a different species if none of the same species are available. In the wild more options are available and an individual of the same species would most likely be picked. IMO proximity with lack of other suitable choices is the paramount reason interbreeding takes place.
:I have found Black Racers under the same stones as Garter Snakes. I have seen Western Diamondback Rattlesnakes only a foot or so from Sidewinders and Mojave Rattlers. I have found up to six species of snake under the same flat stone at the same time. The six species were: Smooth Green Snake, Eastern Milksnake, Garter Snake, Red Bellied Snake, Ringneck Snake, Northern Banded Water Snake. A Dekay’s Snakes may have been a seventh
(snip)
:I have found Emory’s Rat Snakes (Corn Snake subspecies Elaphe guttata emoryi) and Gopher Snakes under the same piece of debris.
(snip)
:Snakes of different genera and species do cross one another’s paths in nature – so if they would interbreed in captivity, why not interbreed in nature when in such close proximity to one another? (Or is it that they do interbreed in nature but as of yet we have not recognized the results?)
The snakes that you mention (with a few exceptions) are all from different genera. It is widely accepted in the scientific community that animals of different genera cannot interbreed. Only animals belonging to the same genus can interbreed and will only provide viable offspring if they are in fact member of the same species. Scientists do use rather circular logic here as lack of gene flow is a prerequisite of speciation. For example: a Chihuahua and a great Dane may not be able to mate due to size differences, but can have gene flow through intermediate matings, thus are the same species. With snakes this problem does not exist and we can assume that if black racers and milksnakes cannot produce offspring, it is because they are separate species. Taxonomy is fairly fluid and genus assignments can change, but the actual genetic makeup of the species is relatively stagnant. Taxonomy is merely an attempt to categorize messy reality. That being said, we have reached a state of knowledge where the majority of genus assignments are reflective of reality. Why don't the snakes that can interbreed do so? I maintain it is because in the wild they have better choices available to them.
:While you may believe it next to impossible for snakes of different species to cross one another’s paths in nature,
I do not believe this at all. I was referring to two specific snakes, Morelia spilota (Carpet Python) and Chondropython viridis (Green Tree Python). These animals would usually never meet in the wild, as one is arboreal and the other is not. You should note that these are currently defined as being in different genera and so according to my earlier comments should by no means be capable of producing offspring. The Green Tree Python is moved every few years into the Morelia genus and then back to Chondropython. The interbreeding I described earlier makes me lean strongly to the camp that would place them in Morelia. (BTW the snakes you mentioned earlier that are in different genera have all been so since at least the late 1800s)
: There may have been quite a different outcome for the offspring had the incubation procedures been changed from what they were. Temperament, fecundity and so forth may all have been affected negatively by improper incubation procedures for these interspecies eggs;
The eggs were carefully maintained in an incubator in a manner that was suitable for eggs of either species, as they have similar requirements.
:Until scientific research were to be done about why the offspring turned out the way they did, little can be said, short of assumption, as to why they now behave as they do.
True, but the original poster asked for opinions and I clearly stated at the end of my post that I gave such. IMO it was the breeding that was at fault.
:You also asked: “If however, you breed reptiles because of a true fascination with the natural world and it's wonders, why would you want to try to "improve" on nature?” I don’t think I ever said or implied that nature, as you seem to be referring to it, would necessarily be improved by an interspecies breeding project.
You did not. My bad. I meant it as a general "you", as in anyone who interbreeds species.
:Nature, however, is constantly being improved (or at least changed) by itself, and that includes any changes to nature made by man. Mankind, after all, is only one small part of nature. As I said in my post, it would be rather interesting if such breeding were to take place, and the hobby would become more interesting, in my opinion. My goal in talking about the possible increased interest that would be generated was to point out that such would be more interesting because things that are new are usually considered interesting by inquiring minds.
(snipped lots of good examples of how man tries to improve on nature)
:I guess this should answer your question, although I could point out many other reasons why one would want to “improve on nature” as you put it.
How do mixed species snakes "improve on nature"? I understand you think they make the hobby more interesting, but that's not really the same thing. My point is that if you breed reptiles because of a fascination with the natural world, a mixed species animal would not be very attractive to you as they are unnatural. I guess I worded it poorly.
: In writing about such breeding projects, my goal was not to suggest that such be done for the sake of novelty (as in fad).
Uh, you did say "My goal in talking about the possible increased interest that would be generated was to point out that such would be more interesting because things that are new are usually considered interesting by inquiring minds" Isn't that what novelty is- new things?
: Interspecies snake mating attempts could be undertaken for a number of scientific reasons, as explained in the preceding paragraph, that would help us better understand the natural world. They could quite possibly lead to scientific or medical breakthroughs in the fields of genetics, medicine, agriculture and so on.
I thought hard on this one and I have to agree that there could be scientific knowledge to be gained from selected breeding attempts. The problem is that the vast majority of hobbyists do not do these breedings for research, and those that do usually do not follow proper scientific protocols, making any results suspect. The ones that do follow correct protocol do not have available to them the tools necessary to properly analyse genetically or medically important data. There are exceptions to this, but they are few and far between. Scientific investigation on this level is not really within the realm of the hobbyist, which is where most interspecies breedings take place.
:Bear in mind that until not too long ago, scientists had said it was absolutely impossible for different species to interbreed and successfully produce offspring.
Please define "not too long ago". It's been known for hundreds of years that when you cross a horse and a donkey (different species), you get a mule.
: Then it was said that inter-genera mating could not be successful, but apparently this has been proven wrong by snakes that readily interbreed across not only species lines but those of genera also.
Examples, please?
:Then it was said that interspecies offspring could never be fertile and breed true, but wouldn’t you know about it – I just heard that a mule has recently produced an offspring that is a true mule! (I only heard a brief blurb on the radio news the other day, I have to look into this one in more depth).
Please do. No sarcasm at all when I say I would find that information very interesting.
: In my opinion, I find absolutely nothing wrong with someone trying to accomplish a successful interspecies breeding project in order to advance our knowledge. I also find nothing wrong with doing it as a novelty, this time as in fad.
I too believe that if you want to do it as a novelty you should go right ahead, but acknowledge it for what it is.
:I truly believe that even when done for novel reasons such an attempt may ultimately result in a wealth of new knowledge being amassed.
This I seriously doubt for reasons stated earlier.
:Finally, as far as conservation goes, breeding interspecies may actually help conservation efforts. Look at it in a way that you may not have imagined and maybe you will agree. If a few new species were created,
Technically they would be hybrids, not a new species.
:by interbreeding naturally occurring species, might not a prolonged interest in these species commence among those in the herp hobby? If such is the case, interest in naturally available species (as in wild caught) may become lessened as the interest in the ‘designer’ species increases.
You raise a very interesting point here and I am inclined to agree with you.
: Sure some of these snakes could escape, but chances are they may not fit into any ecological niche and would die off.
Why? An amelanistic corn snake behaves the same as a regular one. If released into a suitable environment it should fit in the same. The only drawback I see would be predation risk. Perhaps a predator would more easily see a color morph.
Hmmm. I think that covers most of your points. You really made me have to think. I appreciate it. I hope I've done the same for you.
-Z
:Best regards,
:Glenn Bartley
:
