Reptile & Amphibian Forums

I have been thinking about the common statement that hybrids are more geneticly diverse than locality stock. In the broadest sense this may be true. By that I mean if you just want to take any old colubrid and breed it to any other old colubrid you do have a much larger captive gene pool to select from. That's true.

But what if you want to create a specific hybrid with specific percentages to produce a predictible result? Just for very simple example say you want to produce an unrelated pair of 50% cal king/50% cornsnakes. You would need 4 unrelated "founder" adults, 2 cals and 2 corns. This is the same number of snakes you would need if you wanted to produce an unrelated pair of some particular locality animal.

Now say you wanted to produce a pair of unrelated 25% cal/75% corns. You would need 6 unrelated founder adults to make this cross without any inbreeding, correct? That means you need 33% more founder animals to make that cross if you are to avoid any inbreeding.

I think you can see my point and how the number of animals needed to produce more complex triple and quad species crosses increases more and more the number of founders you need. Again this is only applying to those crosses that are defined as a specific combo with a specific percentage.

First generation hybrids have a larger gene pool to pick from.
Generations beyond that - what gene pool they have to pick from is dependent upon the breeder and how related the snakes he started with are.

IE - I suspect that brother/sister pairings of F1 hybrids have more diversity than brother/sister pairings of F1 locality snakes, because locality snakes have more genes in common to begin with - and they may even have more diversity than brother/sister pairings of F1 stock from very separated but same subspecies parents. But they probably have less diversity than a same species pairing of very unrelated stock.
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3.6 L. getula californiae - 16 eggs (Cal. King)
1.1 L. getula nigrita (MBK)
1.0 Pantherophis guttatus guttatus (Corn)
0.1 Pituophis catenifer catenifer (Pacific gopher)
3.3 Elgaria multicarinata multicarinata - 14 eggs (Cal. Alligator Lizard)

That may or may not be true but sounds reasonable. However I am not talking about how much inbreeding you can get away with in hybrids vs. locality. I am talking about how many founders you need to produce completly unrelated offspring.

If you have a specific goal in hybrids and wish to actually created a stable "breed" of hybrid you will need more founders for the hybrid project than you would for the locality project.

I think this is a valid point because hybridization with no direction could eventually lead to a population of all very similar snakes. To avoid that hybriders need to have specific recipies to make distinct breeds. If your recipie rquires 3 or 4 different species you will need many more founders and outcrossing to maintain it. Plus the more complex the recipie the more limited the availability. How many 25% pyro/25%thayeri/50% cal kings are out there for a hybrider to buy? Virtually none so if that is the specific recipie you want you likely would need to make you're own. Using that recipie a hybrider would need 6 snakes to make one generation of unrelateds. Every time they outcrossed they would need 3 new unrelated founders. Say that over several generations they wanted to outbreed 3 times. That is 6 3 3 3 = 15 founders. A locality project outbreeding the same number of times would only need 4 2 2 2 = 10 founders. How that comes into play in the real world is that most breeders can house only so many individual specimens. Therefore the more complex a particular cross is the harder it will be to get unrelateds from a single source.
My point is that if you are looking into any particular breed of snake, be it a hybrid or a pure, and wish to maintain genetic diversity you cannot simply assume someting is diverse since it's a hybrid.

> I think this is a valid point because hybridization with no
> direction could eventually lead to a population of all very
> similar snakes.

I don't think so.
First generation may have somewhat similar appearances because each gene pair has exactly one gene from each species. However, the F2s will have some gene pairs that have some genes from each species, some gene pairs where both genes come from species A - and some gene pairs where both genes come from species B. All random, no way to know - and the possible combinations are endless.

I think that's why the F2s often look so much better than the F1s do.
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3.6 L. getula californiae - 16 eggs (Cal. King)
1.1 L. getula nigrita (MBK)
1.0 Pantherophis guttatus guttatus (Corn)
0.1 Pituophis catenifer catenifer (Pacific gopher)
3.3 Elgaria multicarinata multicarinata - 14 eggs (Cal. Alligator Lizard)

I think it would take a very long time but if you randomly mixed crosses upon crosses for 200 generations I think it's very possible there would be no distinct "breeds". Not that every snake would be identical, just that there would be no consistent outcomes.
That is why I think eventually hybrids will split into two types, one that just crosses anything to see what happens and the other that creates specific breeds. Those that create specific breeds will run into exactly the same problems that locality breeders run into, maintaining genetic diversity and preventing color and pattern drift.

but hybrid breeders can easily add new blood to their lines. Locality breeders can't do so unless they can legally collect the locality (or their are other locality breeders).

Will it change the look? Probably, but there probably won't be a consistent look anyway unless the species are fairly closely related already.

Look at jungle corns - they are extremely variable in what they can look like.
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3.6 L. getula californiae - 16 eggs (Cal. King)
1.1 L. getula nigrita (MBK)
1.0 Pantherophis guttatus guttatus (Corn)
0.1 Pituophis catenifer catenifer (Pacific gopher)
3.3 Elgaria multicarinata multicarinata - 14 eggs (Cal. Alligator Lizard)

Depends what's in the mix. It is much easier to add new blood to many United States locality projects like graybands, pyros and eastern kings than it is to add to crosses that include Mexican Lampropeltis, Womas, Angolans, etc. Then again it's hard to add new blood to pure projects that include no longer imported species. But that is my point, diversity depends on the accessibility of the species and not on whether it's a hybrid or pure.