Tarantulas being bred for size?

[Charliemum]

OK so a vid popped up on my utube feed this morning about breeding t's for specific trates, what they were trying to achieve is an H. gigas to match the size of a Theraphosa blondi. For this to happen they are line breeding the biggest males back to the females, just off 8 inches being the biggest male and 9inch ish being the size of the female, these are t's he has bred from the original female when he started this task bk in 2011. I am curious though could this really be done? Wouldn't there be genetic problems off "line breeding" as it seems to cause problems with all other sp ? T's have such big sacs aren't there to many to guarantee that all baby's would have these "big" genetics?

Please don't get me wrong I am not bashing this person in any way, I am just curious if this is a possibility, and if so why aren't all breeders doing it to get massive t's? I am curious to see what others think on this subject, is it taboo or is it genius? I can't make up my mind so I thought I would ask on ab to get more information as it's something I have never thought about or heard of others doing tbh .


This is the upload in question.

 

[DonLouchese]

Obviously the animals can carry on the same genes for growth as we do. So for example a woman and a man who are taller than 6'4 have a huge chance their child will be a tall human being. Same should be carried in the spider world. Where if you pick up the biggest female you can have and the biggest male you'd probably end up or have a bigger chance of producing a mature specimen that will grow larger than usual.

But oh well , even us humans are limited to some extent and so are spider species on it's own. I very much doubt you can get more than 2" out of a certain genus. Even less for dwarf species.

Regards,

Don

 

[Charliemum]

Obviously the animals can carry on the same genes for growth as we do. So for example a woman and a man who are taller than 6'4 have a huge chance their child will be a tall human being. Same should be carried in the spider world. Where if you pick up the biggest female you can have and the biggest male you'd probably end up or have a bigger chance of producing a mature specimen that will grow larger than usual.

But oh well , even us humans are limited to some extent and so are spider species on it's own. I very much doubt you can get more than 2" out of a certain genus. Even less for dwarf species.

Regards,

Don

That was my thoughts! surly any creature can only get to a maximum size regardless of breeding large sp with large sp and wouldn't breeding back sons to mums n sisters weaken the genetics like it does with other creatures ? I just found it strange and haven't heard of others doing this in the hobby but I am only 3 years into my tarantula journey so I was curious what others thoughts were on this if it was as far fetched as I thought or if it was just something I hadn't learned of yet. You don't ask you don't know

 

[viper69]

I’ve done line breeding of H chilensis, and now I have one that is 11” DLS.

 

[Charliemum]

Ah @viper69 I was hoping you would chime in I assume by your response its a futile effort and probably a rather silly one at that?

 

[birdonfire]

I'm thankful for genetic diversity.

 

[Mike Withrow]

This species is in such a mess anyway. I'm not understanding why this attempt is being made when people don't honestly know what they have to start with. I've seen a couple of sketchy posts already.
It was interesting to watch tho I have to admit.

 

[BoyFromLA]

I’ve done line breeding of H chilensis, and now I have one that is 11” DLS.

Hercules chilensis.

 

[viper69]

Hercules chilensis.

how did you know!!!

 

[BoyFromLA]

I am curious though could this really be done?

If it was, then I would do exact opposite. Make Theraphosa blondi a dwarf.

 

[Charliemum]

If it was, then I would do exact opposite. Make Theraphosa blondi a dwarf.

that would be so cool

 

[spideyspinneret78]

Hercules chilensis.

AKA giant flame rumped chilean birdeater

 

[MariaLewisia]

Given my background of having studied genetics in vet med plus what I've read about invertebrate inbreeding/linebreeding/selective breeding, my semi-educated guess is that this experiment might very well produce bigger, faster growing spiders... but those spiders will not be healthy and their lifespans will be dramatically affected in a negative way due to genetic erosion.

Invertebrates have much less visible mutations going on than vertebrates when it comes to things like inbreeding, but that doesn't mean nothing is going on with their genome when they're bred with only one trait in mind. You can't see all the other stuff that's lurking that follows that one, sought-after trait, until suddenly individuals seem to fail to thrive and/or die off for seemingly no reason.

So unless other bloodlines of the Hysterocrates are introduced, OR the breeding is highly monitored and things like this are already kept in mind, we are probably watching a steady decline in fitness until no specimens are able to reach adulthood and able to reproduce.

 

[sparticus]

Selective breeding absolutely can impact the gene pool in a population over time, but it tends to take many generations to get there. It's not surprising, humans tend to eventually start selective breeding pretty much any species we breed in captivity because we like things that are "different". See dog breeds as an example. Or goldfish, or betta fish, or isopods, or horses, or cats, or plants. We do it to pretty much everything, given enough time. Seems like it's just human nature. The ethics of it, though, are an entirely different conversation.

 

[spideyspinneret78]

Given my background of having studied genetics in vet med plus what I've read about invertebrate inbreeding/linebreeding/selective breeding, my semi-educated guess is that this experiment might very well produce bigger, faster growing spiders... but those spiders will not be healthy and their lifespans will be dramatically affected in a negative way due to genetic erosion.

Invertebrates have much less visible mutations going on than vertebrates when it comes to things like inbreeding, but that doesn't mean nothing is going on with their genome when they're bred with only one trait in mind. You can't see all the other stuff that's lurking that follows that one, sought-after trait, until suddenly individuals seem to fail to thrive and/or die off for seemingly no reason.

So unless other bloodlines of the Hysterocrates are introduced, OR the breeding is highly monitored and things like this are already kept in mind, we are probably watching a steady decline in fitness until no specimens are able to reach adulthood and able to reproduce.

I'll have to look at the book to find the exact study cited ( my friend is borrowing it at the moment) but a study was done on araeneomorph spiders that showed a rather dramatic decline in overall fitness with each successive generation that experienced inbreeding. Obviously these weren't theraphosids so some of it may not be applicable, but it's nonetheless interesting to consider. Some of these traits were not immediately visible, but there was an effect on behavior and lifespan. The book was Spider Behavior: Flexibility and Versatility. Fascinating read.

 

[Charliemum]

I'll have to look at the book to find the exact study cited ( my friend is borrowing it at the moment) but a study was done on araeneomorph spiders that showed a rather dramatic decline in overall fitness with each successive generation that experienced inbreeding. Obviously these weren't theraphosids so some of it may not be applicable, but it's nonetheless interesting to consider. Some of these traits were not immediately visible, but there was an effect on behavior and lifespan. The book was Spider Behavior: Flexibility and Versatility. Fascinating read.

I shall look for the book thank you

 

[TechnoGeek]

Because science.. I'll explain it in details but this will be a long post.

Is it possible? Sure. Selective breeding isn't taboo, or niche, or even uncommon. It's a thing that happens in nature and captive populations. It's how we selected countless species of animals and plants for traits that are valuable and desirable for us. Even in nature, if being bigger helps your odds of surviving and finding a mate, then over several generations your entire species becomes bigger.

Now about your second question, why aren't more breeders doing it? For multiple reasons. One, tarantulas haven't beed kept as pets for long. Heck for a good chunk of their history in captivity we didn't bother with breeding them much, we just collected them from the wild. Establishing certain traits takes multiple generations of selective breeding.

Furthermore, captive breeding projects for the pet trade usually don't have the limitless populations to choose from that nature or industrial breeding projects for agricultural or scientific purposes have at their disposal. This increases the likelihood of inbreeding exponentially, and inbreeding causes devastating consequences to all living things. A good example of this is selecting dogs for size. Most dog breeders don't have sufficient budget to guarantee a diverse enough gene pool in which all individuals share the trait they're selecting for (IE size in this case). This usually means resorting to breeding related animals which has caused many dog breeds to develop horrific genetic defects from bulldogs having breathing issues, to great danes suffering from cardiac defects, to mastiffs with hip dysplasia etc.

Tarantulas are usually cheaper to keep and breed than dogs, by several orders of magnitude, so it might be easier to select them for size.. but I'd still be worried that people might choose to take a shortcut. I mean snakes are much cheaper to breed and raise than dogs and we already have ball python morphs that suffer from genetic problems so severe they can't even strike at their food without biting themselves.

I mean think about it, a hugely popular pet breeder might have a budget in the tens of thousands at best? Hundreds of thousands maybe?? This isn't even chump change compared to the tens or hundreds of millions of dollars in funding that agricultural and scientific research gets from sponsors, corporations, and governments, to say nothing of the much bigger facilities they have at their disposal, and their superior understanding of science and genetics.. this is literally why domestic corn, grapes, and horses don't look like an Austrian Duke from the Habsburgs.

 

[Charliemum]

So others feel/think the same as me, clearly it can be done but at what longterm cost when it comes to the health of the animals, and wouldn't try it themselves for that reason. That was what I thought but I didn't know if what I thought was right or if I was stupid n just hadn't heard of it because I am not a breeder so I asked. I think I have my answer now. Thank you all .

 

[Mike Withrow]

I'm googling my butt off trying to find that book @spideyspinneret78 was talking about.

 

[Charliemum]

I'm googling my butt off trying to find that book @spideyspinneret78 was talking about.

It's on Google play books but it's £53.99.