breeding

[Patrick Gildenhuys]

..

Hi everybody, my first post, so I hope it makes sense.
Firstly: I'd take an inbred, pure B.albopilosum anyday, over some of the dodgy B.angustum, B.schroederi and B.sabulosums that have been floating around lately.

Secondly: I don't think anyone would breed mother/son etc. if faced with the oppurtunity of mating a mature female with an unrelated male. What would the motivation be behind this?
I'm pretty sure that most in/line breeding is done, purely because there are no unrelated males available.

Thirdly: It could never positively be guaranteed that even a wild-caught male has no relation to your captive-bred mature female. Wild collectors would surely frequent areas which supply larger quantities of spiders, therefore somewhere down the line you'd surely encounter a related specimen/s.

Is inbreeding a good thing or a bad thing? Who knows?
Would I do it? Probably. If no unrelated specimen was available...definately!

[mary walters]

Just to say I have a spider that is bred to her son, purely because the male we borrowed she had no interest in at all, so we thought we would just try him, bingo, waiting for a sac now. It was a spur of the moment thing and I DON'T make a habit of it.

[Stanley A. Schultz]

SIGUE HEIL



Shouldnt have played god and removed all the " " should you?

...

I will not respond to this beyond saying that you obviously have some personal ax to grind, and I will not become a part of that sort of discussion.

If and when you can come up with some legitimate questions or are willing to debate the issues rather than the personal feelings, I'll get back to you.

[Stanley A. Schultz]

Layzell, J. 1990. Inbreeding. Journal of the British Tarantula Society, 5 (3): 12.

Clapp, J. P. 1996. Inbreeding of tarantulas. Journal of the British Tarantula Society, 11 (4): 132–134.

Gabriel, R. 2003. Food for thought: common names and inbreeding. Journal of the British Tarantula Society, 18 (3): 89–91.

With thanks to Richard Gallon's index of BTS journal articles Vol 1(1) – 22(2)

(The journal containing Ray's article is available to BTS Members on the members site).

Where can I get hard copies of these articles? I need to study them before I can comment on them.

[Stanley A. Schultz]

A spider is not a rabbit though, and how can you directly compare vertebrate mammals and birds with invertebrate arachnids? ...

Quite easily, it turns out. All the organisms you mention plus a lot more are technically "multicellular eukaryotes." These include all plants, all animals and a bunch of things that you'd think are straight out of your fondest nightmares. All these creatures, every last one of them, use the same basic methods for replicating chromosomes, sorting genetic material, producing gametes, and combining genetic material to produce new individuals.

Over the last 150 years since Gregor Mendel published his seminal papers, geneticists have developed and refined the "Laws of Genetics" that rivals Newton's Law of Gravity in stature. Today, there are variations in the way that multicellular organisms pass genetic traits from generation to generation, but there are NO, read that as "zero," exceptions. If you think there are, I challenge you to bring them forth for examination and discussion here and now.

The same rules that describe the way that genetic traits are inherited in sweet peas (Mendel's model), fruit flies, rabbits and humans also apply without exception to tarantulas.

... Evolution by means of natural selection does not occur instantly in the wild, it happens when a population shows selective genetic change over time.

But we're not talking about evolution (which attempts to explain the mechanism behind speciation) here. We're discussing animal husbandry (which occurs in a completely artificial, man-made environment) and comparing it with a parrellel phenomenon that occurs in nature.

[Stanley A. Schultz]

... there is no research known by me on inbreeding in Theraphosids ...

It seems to me that Rick C. West actually did a small experiment with inbreeding some species of African tarantula over several generations and found that with each successive generation of inbreeding, various "bad" characteristics became more and more prevalent. I think he even published the results either in the BTS Bulletin or in the ATS Forum Magazine. Perhaps someone else would wish to look it up and do a "book report" on it.

... results all conclude that over a long period inbreeding is bad. ...

Only partially correct. In fact, the principal, if not the only, way that we can isolate and conserve desirable characters is through inbreeding.

The laws of genetics work equally with survivor genes and killer genes, the good, the bad and the merely ugly. So along with isolating those desirable genes we are inadvertently isolating some associated not-so-desirable genes.

And, that's where good animal and plant husbandry comes into play. Inbreeding with no artificial selection (aka "culling") is bad because it does nothing to remove the not-so-desirable genes.

I am at a complete loss to explain the apparent lack of belief and understanding among arachnoculturists of this basic principle. This is not rocket science, it's basic good breeding, something that we have done with our farm animals, our other pets and ourselves for millennia. (As an example, witness the issue of hemophilia in the royal families of Europe, and their efforts to extirpate the gene from their "bloodlines.")

[Patrick Gildenhuys]

..

Where are the lines drawn, and who draws them though?
The breeder who is looking for colour/body shape/number of offspring/resistence to mites...or the purist who is looking to keep the colour/body shape/number of offspring/resistence to mites as close to natural as possible?

Everyone has differing ideas as to what is desirable. A Haplopelma minax that is bluer, and larger and more docile, would be the ideal, average tarantula keepers pet. And needless to say, with years of selective inbreeding, this might be achievable, but is it a Haplopelma lividum anymore? In nature those blue, big, docile ones would be the first on any predators list. Easy to spot, and easy to handle.

Is a Kohaku koi, still a carp? Yes, but selectively inbred into an abomination.(In some eyes)

So my question again is...where are the lines drawn, and who draws them?

[Stanley A. Schultz]

so what if i breed some ts ,that are related ,eggs left with the mother and half come out with 3 legs imstead of 8, they seem to be feeding and growing , true they keep turning around in circles,
now do i cull these or what

of corase they would be culled,

and the half that turned out good ??
sell as normal ?
cull them, and never breed that pair again?
i know what i would do!!! ...

A good point. I will not consider your specific example, but address the question with a slightly more realistic example.

What if you were suddenly blessed with a tarantula that had its colors reversed? Where there was red there is now black and where there was black there is now red.

What would you do? If you were a born, dyed-in-the-wool, purist, you might kill it, or at least never attempt to breed it.

Some other hobbyist may think it's cute and breed it so that its mutated gene is conserved as a curiosity.

The breeder who is in the business might breed it to the maximum without hesitation because it represents a huge, commercial "golden egg."

Which is "right?" The answer to that is unclear. Given that those tarantulas will never be returned to the wild, they do not pose any sort of threat to the natural order of things. Let's face reality. Of all the animals and plants that have ever been bred in captivity, you could count the total number of species that were used to reseed natural populations successfully on the fingers of one, or at most both, hands! So that argument is a non-starter.

Does the maintenance of that aberrant strain of tarantulas pose any threat to the hobby. Not at all. In fact, it may represent a significant boon because it will doubtlessly foster an even greater interest. Is it a threat to any economic interests? What do you think when everybody on this and every other forum who sees one the first time swears that they "gotta have one!"?

Is it somehow amoral, immoral, or unethical to maintain the strain? Here we're getting into your "beliefs," and not only am I not going to try to change them, I and most of the other readers on this forum really couldn't care less about them. It's a free world and we do what we want. And once we saw the photo we wanted one of them.

... inbreeding dont think there be any problems untill a good few genarations down the line, ...

No. The problem is now. They'll only surface a few generations down the line. It's an important difference in concepts.

... plus by bring in new wild type stock to keep the line strong, what would happen if tarantula imports were banned in the uk? we would have one gene pool to work with some imbreeding would def occur

Quire correct. Then, we would definitely have to turn to practicing good animal husbandry or face the possibility of keeping vastly inferior animals or lose the strain or species entirely.

So it would seem that we can either begin to practice good husbandry now, or wait until then and try to unscrew what we, perhaps ignorantly, perhaps greedily, screwed up now.

[Stanley A. Schultz]

Hypothetical question for you then. ...

Not so hypothetical as you might think. This actually has happened several times with tarantulas already.

... Say I had a wild caught female of a new species that came in misidentified with an import lot but is plainly not what it's labelled ...
Do I :

a) selfishly keep it to myself, raise the slings to adulthood and then watch as they all worthlessly die?

b) identify the males, wait for them to mature, and then breed them together with their siblings or set up a breeding group amongst some trusted colleagues, so that the species can be introduced into captivity? ...

I'd inbreed it with the specific goal of maintaining the species in captivity. If it turned out to be a financial success, that's a bonus! But, at least I and other hobbyists would be able to enjoy a truly unique species.

... It's not as simple or as clear cut as saying inbreeding is bad or inbreeding is good.

You are quite correct. I'll say it again. Inbreeding, in and of itself, is not bad as long as it is balanced by good husbandry practices:

1. Being as careful as possible about the source breeding stock to avoid as many undesirable characters as possible (aka selective breeding).

2. Intense, artificial selection (aka "culling") of the resulting offspring to weed out any that are undesirable or defective.

[Phil Rea]

Quite easily, it turns out. All the organisms you mention plus a lot more are technically "multicellular eukaryotes." These include all plants, all animals and a bunch of things that you'd think are straight out of your fondest nightmares. All these creatures, every last one of them, use the same basic methods for replicating chromosomes, sorting genetic material, producing gametes, and combining genetic material to produce new individuals.

Over the last 150 years since Gregor Mendel published his seminal papers, geneticists have developed and refined the "Laws of Genetics" that rivals Newton's Law of Gravity in stature. Today, there are variations in the way that multicellular organisms pass genetic traits from generation to generation, but there are NO, read that as "zero," exceptions. If you think there are, I challenge you to bring them forth for examination and discussion here and now.

The same rules that describe the way that genetic traits are inherited in sweet peas (Mendel's model), fruit flies, rabbits and humans also apply without exception to tarantulas.

In my humble opinion, you cannot compare reproduction of spiders (apart from the inherent biological processes within reproduction and genetics, such as meiosis, the production of gametes etc.) with the reproduction of more complex organisms.

What I was getting at Stan (or trying to), is that beyond the inherent genetic processes that occur within reproduction of diploid eukaryotic organisms, reproduction within spiders can't be directly compared to that of higher organisms.

It seems to me that we have much more knowledge of the genetics of higher organisms that we do spiders.

I wasn't proposing an alternative to Mendel

But we're not talking about evolution (which attempts to explain the mechanism behind speciation) here. We're discussing animal husbandry (which occurs in a completely artificial, man-made environment) and comparing it with a parrellel phenomenon that occurs in nature.

My point about evolution was directly in answer to a point that wesley made. It was not a standalone statement.

Incidentally, this year also marks the 150th anniversary of the joint publication of papers by Charles Darwin and Alfred Russel Wallace separately introducing the theory of evolution by natural selection

[Stanley A. Schultz]

... Ok Wesley and Stan, both proponents of culling, with your infinite wisdom and abilities far beyond the normal person ...

Thank you for the compliment, but I question if we really have any qualities beyond the normal. I'm more inclined to think that the few people who were monitoring this discussion have either grown bored or disgusted with it and moved on to other issues, or are lurking in the background, amused by the circus.

... can you indicate which are the following from the picture please? ...

1. The best feeders
2. The worst feeders ... [/quote]


No, no, no! You miss the point entirely! Obviously we can't select for any of those qualities, at least very easily. Therefore, your question is superfluous.

Maybe in 100 years there will be a litmus test for some of the things you propose (although I'd be astounded!), but not now and not soon.

We can only select for the qualities we can recognize. In the rather recent past I have seen references and mention to such things as defective eye fields, lack of spinnerets, and high incidence of molting problems among babies. There may be others.

It is also possible that there are relatively benign mutations cropping up, such as different colors, smaller or larger stature, ability to breed more successfully in captivity (a secondary quality dependent on some as-yet-undefined primary mutation), and others.

When these arise, the enthusiasts who possess the effected individuals must make a value judgment about whether or not they are worth conserving. That judgment, of necessity must be based on personal beliefs and priorities, and I'm not going to go there. It is important for them to understand their options and the working principles involved, however, so they can make an informed judgment, not one based solely on knee jerk reactions or muddled thinking.

[Stanley A. Schultz]

What I was getting at Stan (or trying to), is that beyond the inherent genetic processes that occur within reproduction of diploid eukaryotic organisms, reproduction within spiders can't be directly compared to that of higher organisms. ...

But those reproductive details "beyond the inherent genetic processes that occur within reproduction of diploid eukaryotic organisms" are irrelevant in the present discussion of animal husbandry.

... It seems to me that we have much more knowledge of the genetics of higher organisms that we do spiders. ...

Specifically, yes. But they still follow all the rules with only rather minor variations. While we may not know of any specific spider gene that influences any specific spider character, there is no question that such a gene would be replicated, sorted and recombined with it's allele (duplicate/partner on the other chromosome in a pair) just as any similar pair in any other multicellular organism.

... I wasn't proposing an alternative to Mendel ...

No. But, at other times other people have inferred that tarantulas or spiders, in some way, inherited their characters by some different method. There is not one shred of evidence to support such a claim; and the overwhelming weight of evidence, though circumstantial, excludes it.

... Incidentally, this year also marks the 150th anniversary of the joint publication of papers by Charles Darwin and Alfred Russel Wallace separately introducing the theory of evolution by natural selection

Really? It's been that long! I remember it almost like yesterday!

(Just kidding!)

It also marks the 50th anniversary of the publication of William J. Baerg's little book The Tarantula and what we consider to be the beginning of the arachnoculture hobby. Strange but true, I CAN remember that day! I was 15 years old.

No kidding!

[Ray Gabriel]

I will not respond to this beyond saying that you obviously have some personal ax to grind, and I will not become a part of that sort of discussion.

I find it rather repugnant that someone in your position would propose

ruthless culling of crippled, imperfect, slow, small or otherwise undesirable individuals is done.

Of any species,

me being not exactly what i would call "normal" which is very probably like other members of this website, (which either through societys or thier own choice) are not to regarded as normal Do not agree with your ideals of only having "quality" specimens in a population.

I think an apology is in order to those people you may have offended?

But back to spiders

like i asked previously

What in your eyes are

crippled, imperfect, slow, small or otherwise undesirable individuals

?

what in your eyes is not

quality

?

Ray

[Ray Gabriel]

1. The best feeders
2. The worst feeders ...

No, no, no! You miss the point entirely! Obviously we can't select for any of those qualities, at least very easily. Therefore, your question is superfluous.

You Said

[QUOTE=Stanley A. Schultz;22225] If we save every blinking baby tarantula without manually culling out the "undesirable" ones, our captive stock will gradually deteriorate like some breeds of dogs have. [QUOTE]


So i asked a legitamate question " how do you differentiate all the bad spiderlings from the good good spiderlings ?".

If you are proposing culling (which i personally abhor) then you must have a way to separate the good stock from the bad stock at spiderling. Your comments not mine.

Please tell us its your proposal

Ray

[Nick L]

I would just make a few points generally about inbreeding (i.e. not specifically related to Ts)…

1. Inbreeding ‘in nature’ is widespread and common. Indeed it is a consequence of one of the main mechanisms of speciation – look up ‘Founder Principle/Effect/Theory’.

2. Is it ‘bad’? Well ask any group of geneticists or evolutionary biologists and you wont get a consensus of opinion because the research that has been done is expansive and conflicting. For every paper that you’d care to site I’ll find you a contradictory one (I’m talking of peer reviewed ‘scientific’ papers in mainstream journals here). There is quite convincing evidence that it can be beneficial in the long-term – deleterious gene effects appear to be more common in first few generations; such individuals are quickly ‘weeded out’ by natural selection leaving in subsequent generations a genetically ‘fitter’ population compared to an outbred population (deleterious recessive genes are effectively removed from the population genome in the first few generations; thereafter even the incidence of deleterious gene expression is lower compared to a ‘normal’ outbred population i.e. they are ‘fitter’ than a ‘normal’ population.).

3. The deleterious genetic effects that can occur with inbreeding tend to be ‘catastrophic’ i.e. the embryo fails to grow at all or dies before it has fully developed so in the case of Ts most of the negative effects will only be apparent within the egg sac. The slings that emerge are likely to be as ‘healthy’ as any.

4. ‘Culling’ strikes me as an inherently bad idea. As has been pointed out in other posts, on what criteria do you do it? Indeed how do you know how to play ‘God’ by imitating natural selection? Natural selection is not a ‘guiding hand’ – there is no direction, no ultimate goal, it chops and changes and is constantly going on. Keeping Ts in captivity is subjecting them to a variant of ‘natural selection’ anyway (remember all of those unexplained deaths?) – if they are surviving your husbandry (and are therefore ‘adapted to their environment’) who are you to say that particular individuals should be culled because of some other criteria that you’ve decided upon – if you are aiming for a genetically ‘healthy’ population then you should be MAINTAINING that variability NOT reducing it by culling.

5. A more specific point here…

In my humble opinion, you cannot compare reproduction of spiders (apart from the inherent biological processes within reproduction and genetics, such as meiosis, the production of gametes etc.) with the reproduction of more complex organisms.

Why not? There is no difference. Sexual reproduction is the SAME though-out; the ways in which it is achieved is the only aspect that you cannot compare and that is irrelevant here. How are you defining ‘complex’? There are many known examples where ‘simpler’ animals have far more genetic material than more ‘complex’ ones such as us humans. More is know specifically about the genetics/reproduction of the ‘simple’ fruit-fly than anything else but because there is no inherent difference in the mechanics of it all by inference this knowledge can be applied to humans.
Theraphosids are going to be no different to fruit flies or humans in terms of genetic mechanisms. No one is ever going to study the genetics of Ts (DNA sequencing for taxonomic purposes excepted) because the generation length is just too long – the favoured tools (species) for the geneticist have very short generation times so that results can be quickly seen. So, the favoured choices are fruit-flies, zebra fish and mice – if the mechanisms weren’t comparable to humans I doubt we’d be studying them to the degree that we are.

I’ll leave it there with my comments but would just say that this topic generally (not just in relation to Ts) is one that is awash with misconception and misinformation in the public domain. However, you wont get a definitive answer from the scientific world either! Personally I have no problem with it.

Nick