Lets talk about hybridization.....

Alexander, those are subspecies, not species designations. Any 'mixing' of subspecies is termed an intergrade, and not a hybrid.

I know that, this is what Gregg said:

Originally Posted by Gregg M

Look at Boas for example..... Do you know for sure you are getting a pure hog or any other sub-species???

A hog island boa is the same subsecies as "central american boa" so it is not even an integrade, because they are the same subscies.

Even if they arent pure hogs. hogXcancun boa= central american boa hogXcorn island= central american boa (central american boa is a kind of loose term for BCI "mutts")
Boa localities are not subspecies, and they are definetly not full species. They are kind of like breeds of dogs. Labrador retrieverXgolden retriever=mutt, central american boa=mutt, central american boa=/hybrid=/integrade.

Originally Posted by sirenofthestorm

Alexander, those are subspecies, not species designations. Any 'mixing' of subspecies is termed an intergrade, and not a hybrid.

Seems to me that "hybrid" is perfectly acceptable in the context. Definition of "hybrid":
1 : an offspring of two animals or plants of different races, breeds, varieties, species, or genera

Source: Merriam-Webster's Medical Dictionary, © 2002 Merriam-Webster, Inc. (see www.dictionary.com)

If you are going to define a hybrid I would suggest you use its biological meaning in this context not that of some dictionary.

Biologically a hybrid is a cross between to individuals that represent the lowest taxonomic ie species. Thats basically a summary from Mayr's Principals of Systematic Zoology.

So a hybrid is a species cross, which is what people have mostly aluded to here.

In my own research (I am a taxonomist and have worked with a lot of natural hybrids) I have found that the ability to hybridise is actually the norm and the inability a derived condition. Inability includes unsuccessful hybridization ie infertile offspring. A viable hybrid to be successful must be able to produce a second generation.

Interestingly one of the species I described, Chelodina canni McCord and Thomson 2002, has not only viable wild hybrids (demonstrated using electrophoresis) but the hybrids have hybrid vigor which is the hybrid is a larger, stronger animal then either parent species. Turtles of the genera Chelodina and Macrochelodina are also capable of multiple hybridization. For example a Macrochelodina rugosa x Macrochelodina parkeri offspring can successfully breed with a Chelodina novaeguineae, resulting in a 3 way hybrid.

My point in this is that as hybridization is a primitive condition it actually cannot be used in taxonomy. Hence the fact that two species can hybridize or even different genera has absolutely nothing to do with wether or not the parent populations are different species, or any other higher taxon.

You cannot call subspecies crosses hybrids because by definition a subspecies must be able to breed with other subspecies, and successfully. A subspecies is an allopatric population that in 75% of cases can be distinguished from 100% of the individuals of another subspecies of the same species (again from Mayr). That is all. Subspecies are geographic variants of the same species and do not represent a taxonomic unit, the smallest unit in taxonomy is the species, it is also the only real taxonomic unit. Subspecies are matters of convenience and interest only.

Ok now that I have put up what is and is not a hybrid and its importance taxonomically. From a breeding perspective they should not be bred. Here in Australia it is actually illegal in some states to produce them deliberately. When hybridising animals you are playing russion roulette with their lives there is no garuntee what will happen, the genetic mix may kill them, leave them with a life of pain and suffering or on rare chance give a reasonably healthy animal. No garuntees.

Cheers, Scott

Scott Thomson

Right. A cross at anything above the subspecific level is a hybrid. The term intergrade is used when subspecies are crossed. I actually get a kick out of people that vehemently speak out against intergrades, for the following reason: They occur in nature. Who is to say that the founding stock of any carpet python is "pure", when several of the subspecies are known to interbreed. The same goes for Rattlesnakes of the lutosus complex. There are numerous examples, but that point has been made. Personally, I like many of the intergrades - in some cases, they can be be stronger, heartier, and more beautiful than the pure forms. Conversely, I am not a proponent of hybrids...sure, some of them are interesting - but alot of that is just "freak fascination". Break out the proof that the animal is as strong, or stronger, than the originating species, and I'll be happy to reconsider (your examples are duly noted, Scott...and very interesting)

As for the

One thing I neglected to mention in the wild hybrid zone for C. canni x C. longicollis is that although they have an apparent hybrid vigor (female hybrids are up to 30cm (15 inches) carapace length easily 5 - 8 cm (2.5 - 4 inches) longer than either parent species) the hybrids are restricted to the overlap zone between the two species. This says that despite the larger size and aparent success of the hybrid locally it is incapable of competing with either parent species hence does not extend its range beyond a few kilometers north or south.

As for intergrades, this is actually also a specific term and is resticted to cases of interbreeding between subspecies where they overlap. Personally I think that the presence of intergrades shows that the two forms are not subspecies but are the same subspecies. They actually fail the defining test of a subspecies which is that they are allopatric ie never occur together. So if intergrades are found how can this be true.

So intergrades are only crosses between subspecies that are found geographically next to each other in the wild.

If someone is crossing subspecies from opposite sides of the country they are just crosses, nothing more, they are not intergrades as intergrades can only be wild caught and can only be between abutting populations.

Wether they should be crossing them is up to the individual, personally I would not allow anything to breed that is potentially different.

Hybrids of course are another matter and they should not be produced.The hybrids I work with a wild hybrids, freaks of nature if thats the term people want, but they have not been deliberately produced and are matters of scientific interest to me only.

Cheers, Scott

Originally Posted by Scott Thomson

As for intergrades, this is actually also a specific term and is resticted to cases of interbreeding between subspecies where they overlap. Personally I think that the presence of intergrades shows that the two forms are not subspecies but are the same subspecies. They actually fail the defining test of a subspecies which is that they are allopatric ie never occur together. So if intergrades are found how can this be true.

So intergrades are only crosses between subspecies that are found geographically next to each other in the wild.

If someone is crossing subspecies from opposite sides of the country they are just crosses, nothing more, they are not intergrades as intergrades can only be wild caught and can only be between abutting populations.

I must have edited out the part about range overlap. I got a bit verbose, and my post wandered quite a bit...I chopped at least half of it before it was submitted. Once again, some good points - I hadn't considered the last one.

people often say in defense of hybribization "if it can happen it will happen" but that often isnt the case. for example the "liger" or lion tiger hybrid. theoretically a lion and tiger could physicly breed but locality would prevent it. or when refering to herps the "super ball" or blood x ball python hybrid could happen but would never happen in the wild. and most of these animals ate sterile anyways so i dont think we should do it period.

a blood ball, or a super ball is totally fertile. Roussi's reptiles have bred F1's, @'s and i think 3's. I agree that nothing about how we keep snakes is "natural". I really feel that if you wanna keep blood lines pure and such perhaps morphs should not be bred, and many of them, like albinos, cant and usually dont survive in the wild. I'm not sure how true this is for reptiles, but i know that some kinds of albinism or colorings in animals are linked to bad or lethal genes. Simply because there are unscrupulous people out there shouldint be reason enough not to breed hybrids. By that logic, since there are irresponsible/uninformed people out there, no one should have large snakes or varinids. A lot of the hybrids i have seen have quite a bit of hybrid vigor. I used to breed king snakes and would regularly cross them with corn, gopher and milk snakes. Were there deformed offspring? Sure, but no more than you would get in a non hybrid clutch, and just as most breeders do, i culled animals that were deformed or otherwise defective. The demand for designer animals seems to be growing in so far as i can see) and realistically, you can only get so many morphs out of say a ball python. In short, im not a big fan of trying to tell people what to and what not to do, i feel that we have enough people trying to tell us as reptile keepers what we can and cant have.