Inbreeding depression and selective breeding?

[Krynn]

With the constant plethora of threads relating to genetic abnormalities (spider wobble, kinking etc.) i am constantly thinking about the genetic quality of the ball python population in general. I am posting this thread to see what general consensus is in the BP community on a few genetics topics.

Inbreeding depression:

Ill start off with the wikkipedia definition:
Inbreeding depression is the reduced fitness in a given population as a result of breeding of related individuals. It is often the result of a population bottleneck. In general, the higher the genetic variation within a breeding population, the less likely it is to suffer from inbreeding depression.

Inbreeding seems to be a fairly common practice in ball python breeding. After all, inbreeding is often the only way to isolate a new gene that pops up due to genetic mutation. Although inbreeding can be a very useful technique to isolate genes, it seems to me that it is done quite a bit more then necessary for the ball python population in general. For example, "breeding pairs" are often sold from the same clutch, and that clutch may have already been subject to inbreeding in its recent ancestors. Is inbreeding depression something that you guys strongly consider when you are purchasing and pairing up BPs during the breeding season? Do you guys think that certain genetic problems (in particular kinking) may be linked to inbreeding depression in certain lines?

Selective Breeding:

In my opinion, the lack of selective breeding is having a fairly strong negative impact on the genetic quality of BPs. Although selective breeding can have an impact on alot of visual aspects of color mutations for example (perhaps the browning out of pastel BPs) I am going to focus on a trait that effect the overall health of a BP.

Since the head wobble seems to be tightly associated with the spider morph, it seems to be less likely that it is the result of inbreeding depression. I think that the head wobble is a prime example of why a lack of artificial selection can degrade the genetic quality of a species. This hypothesis is based off of a certain assumption that i hope to get a bit more insight from in this post:

It is my assumption that people will continue to breed an individual with the spider head wobble. So my questions to you guys are:
1.) Do you selectively breed your ball pythons, or do you breed anything that WILL breed?
2.) Do you think that consistently breeding BPS with "faulty" genes is polluting the BP gene pool?

I realize that this post may be a bit controversial for many, but I think that the responses to this post will be quite interesting in viewing what the general consensus in on these topics. Let me know what you guys think!

[MoshBalls]

Well said. We are just getting started and are selecting our animals to breed in the future and yes I am concerned with line breeding. I know it will happen at some point but I would like to avoid it as much as possible. I also wonder if anyone specifically breeds for docility? It seems some snakes are more naturally docile. I know we are currently focusing on the outward appearance of the snakes but I wonder about the other genes that could be selected as well.

I keep mention dogs but they are a great example of how genetics play into dogs. Nova: Dogs decoded, (available on Netflix http://http://movies.netflix.com/WiM...637#height1677) and National Geographic The Science of Dogs (Also available on Netfllix http://movies.netflix.com/WiMovie/Na...637#height1540) Really talks about how a lot of the visual looks of the domestic dog came about because of selective breeding or domestic docility. I think it is very interesting for anyone interested in genetics. Which I am about as much as the animals themselves. (and I love my snakes and dog!)

[RichsBallPythons]

If it wasnt for inbreeding 99% of morphs in the industry would be non existent. Spiders wobble and kinking has nothing to do with inbreeding. Its in their genetics and nothing can be done to stop it. Kinking cane be incubating fault or in their DNA thats passed down

Most who breed non stop for the hell of it are the reason the industry is where its at and market dropping.

Quality breeders will select females for certain males who would make the best result. Only time inbreeding is done is when proving out a new genetic morph.

[jmugleston]

The worry about inbreeding goes both ways. It doesn't necessarily equate to an abundance of deleterious alleles in the populations. It reduces diversity by decreasing heterozygosity. If you have strong lines then inbreeding isn't necessarily a bad thing (random mutation excluded of course). If you have strong lines and in attempt to avoid the stigma of inbreeding you decide to add from weaker bloodlines you just unintentionally added weaker genes to your population.

In captivity we are working with only a small subset of one or more wild populations. We already dealing with an induced bottleneck. Add to it the desire to create the next big thing and the desire to prove out morphs as quickly as possible and we begin exacerbating the situation.

The mutations that are associated with problems (spider and powerball wobbles) are quite popular. The physical effects aren't enough to convince most to avoid them. Through selective breeding, the pattern mutation may be separated from the physical handicaps and all will be well. Since most aren't too worried about it the wobble will continue to be tied to the morphs. It may even be that the proteins which cause the pattern anomaly are associated with proper neurological development or function as well so the two cannot be separated barring some mutation elsewhere in the genome.

The fact is we have a small representation of the genetic diversity seen in the wild. Couple that with the ever increasing desire to have the next new morph or combo and we have a recipe for weakened gene pool. The breeders that are taking their time, outcrossing, and selecting for better patterns, colors, behaviors, etc. will reap the benefits of their patience. I know I spent a few hundred extra for selectively bred morphs. They cost more, but they were worth paying since the breeders took the time to select for better color and pattern. After the market dies down (it will I promise) those that have selected for stock that stands out above the rest will survive and remain while everyone that was in such a hurry and had little regard for their stock jumps ship, sells their generic stock, and moves on to the next craze.

[TessadasExotics]

Only time inbreeding is done is when proving out a new genetic morph.

If only this was a true statement. It may be true for you, but it isn't for every one.


We out cross as much as possible if not every time. We also selectivly breed and take the longer rout when working on our projects. It's not necesarily how many generations that you line breed but how many times its been done before you and then after you that you need to think about. They say it takes 13 or more generations in BP's before some thing bad might pop up. How many generations did the breeder you buy from line breed for your snake? How many times did the breeder before linebreed? Before that?

[Stewart_Reptiles]

1.) Do you selectively breed your ball pythons, or do you breed anything that WILL breed?
2.) Do you think that consistently breeding BPS with "faulty" genes is polluting the BP gene pool?

1/ Yes I have spent a lot of time, effort and money in trying to select and acquire some of the best example of morphs out there.

I do not buy a morph just to say I have it or to breed it, I selectively acquire or hold back morphs that are the best example of the morph I want to work with based on MY personal test ( now the best of a morph will not mean the same for everyone )

So do i breed selectively? Yes but than again based on question 2 maybe not so depending on your or others standards.

Here is the problem with the question number 2, since you have referred to Spider breeding twice, do you consider Spider breeding polluting the BP gene pool and therefore lack of selective breeding?

If you do than I assume by me breeding Spiders and Spider combos I contribute to the polluting of the gene pool and therefore this might not be what you called selective breeding.

Some people do refuse to breed Spiders because of what you refer to their "faulty" gene does that mean they selectively breed their animals and I don't?

I guess it depends if one think the spider gene is faulty as well.

Not such an easy question after all is it?

But I will tell you this I am selective in what I breed and there are morphs I will not breed but Spiders are just not one of them.

[DemmBalls]

I just want to chime in on the Spider "wobble" topic. The spider gene is a dominant gene. Therefore there would be no benefit to inbreeding them. They are probably one of the least inbred of all morphs. There gene just seems to have a "glitch" in it that causes the wobble. I still love the spider morph.

For the most part, I am against inbreeding, but if it is required for a certain project...I prefer to see it go as few generations as possible. I have not seen any proof (backed by facts) that inbreeding has any ill effects on BP's, but my personal ethics tell me not to do it. Just my .02...

[Krynn]

Great comments guys, i was worried that this might turn in to a violent debate but you guys bring up some great points.

Mosh's balls: Hopefully ill remember this post once im done my final exams for this semester, that is a fascinating topic. I know that national geographic did an article a month or two ago (maybe thats what your link is about) about selective breeding experiments in (red?) foxes. They artificially selected for tame foxes in one population, and agressive mean dogs in another. They are trying to isolate some "domestication genes" in wild animals and they seem to be doing a pretty good job. The domestic population has become puppy dog tame, and the agressive one.. well... i dont think i would be wanting to be the one cleaning their cage

If it wasnt for inbreeding 99% of morphs in the industry would be non existent. Spiders wobble and kinking has nothing to do with inbreeding. Its in their genetics and nothing can be done to stop it. Kinking cane be incubating fault or in their DNA thats passed down

Although i do agree that inbreeding is an important tool to isolate genes, I still maintain that it is done to a much greater extent then needed. I completely agree with you about the spider wobble, as it is only found when the spider gene is expressed so this is likely a case of pleiotropy. As for the wobble, is seems to me that it is most common in recessive mutations (caramel, super cinny) so dont you think its a possibility that kinking itself is due to a recessive deleterious mutation? Lets say for a second its not:
If it "in their DNA thats passed down" then it can be selected against!! The thing that worries me is i have seen plenty of people on youtube with slightly kinked animals who will try to breed them if they can. That seems kind of irresponsible to me.

jmugleston:
Great post! The population has definitely gone through a strong bottleneck, but genetic diversity can still be increased by breeding to "less related" individuals. So even though most BPs in North America are probably related in some way, as far as inbreeding depression is concerned there is less of a reduction in heterozygousity when you breed 3rd cousins for example, then when you breed siblings. Just by looking at all the color mutations that are now out there, you can imagine how much the BP population has evolved since it came to north america.

Here is the problem with the question number 2, since you have referred to Spider breeding twice, do you consider Spider breeding polluting the BP gene pool and therefore lack of selective breeding?
.

I can understand why you might begin to believe this after my post; I used the spider gene because it is probably the most talked about deleterious mutation, so it seemed like the most applicable. I want to emphasize that i dont think it is the spider gene that is polluting the gene pool, I think the wobble gene is polluting the gene pool. Sure the two genes may be pleotropic, or they may just be closely linked on the same chromosome.

Regardless, there are spiders that do not have the wobble. Some people on this forum claim there are also some non-spiders that have the wobble from a spider parent. My point is that we can likely select against the wobble, if people steered away from breeding individuals with the wobble. When i get my first spider, it will probably be a long search.

For the most part, I am against inbreeding, but if it is required for a certain project...I prefer to see it go as few generations as possible. I have not seen any proof (backed by facts) that inbreeding has any ill effects on BP's, but my personal ethics tell me not to do it. Just my .02...

Just wanted to mention that there are tens of thousands of studies being done on inbreeding depression, it is quite a hot topic in evolutionary biology. I will admit there has been no studies done on ball pythons in particular, but almost all animals suffer from inbreeding depression. There are a few exceptions (eusocial animals like some ants and bees), but even highly inbred animals like the naked mole rat suffer from inbreeding depression.

The only way to make a population insensitive to inbreeding, is basically wiping all of those deleterious recessive alleles out of the gene pool.

[mainbutter]

I'm just going to keep it short and sweet:

I agree that there is not enough selective breeding in ball pythons these days.. however, for reasons unrelated to the spider wobble and caramel kinking.

Because it's been pretty much proven that these issues are directly related to the single trait, no amount of "selective breeding" will be able to eliminate these problems.

[rabernet]

Regardless, there are spiders that do not have the wobble.

I disagree. There are spiders that have so subtle a wobble that someone not used to looking for the signs will swear doesn't wobble. But there are no spiders that do not have the wobble.

All spiders wobble. Some people may believe and even swear to you that theirs does not wobble, however, put that same snake in front of the "experts" like Kevin McCurley or Ralph Davis, or Tracy Barker - and they'll be able to show you the subtle movements that indicate a wobble is present in that animal. They've seen more spiders than anyone - and every one of them will tell you - all spiders wobble - it cannot be bred out.

Go to any show and look at how the spiders move on display and then compare that to other ball pythons.

I was at Kevin's in October for about 5 days. We talked about spiders, I got to see some of his super cool 4 and 5 and 6 banger animals. Some of them wobbled and he'd say "so - as you can tell - spider is one of the ingredients in this combo".

I know that people WANT to believe that their animal doesn't wobble, but I guarantee you - they all do. Some not noticeably to the un-trained eye, but for someone who knows what to look for - they do.