Hereditary Traits in Tarantulas?

[Sana]

My researching skills are apparently lacking so I have come seeking information again. I'm curious if anyone knows what traits of an individual specimen are likely to be hereditary? The thing that brought this up specifically is temperament. We know when we talk about a species like B. smithi that most aren't terribly defensive but there are individuals that don't fit that mold and can be very defensive. If you pair the oddball B. smithi do you have a higher percentage possibility of more defensive behavior in slings from the sac? And that of course leads me to wonder what other traits may be inherited from the parents. What about the rare LP that isn't a garbage disposal?

All of that said I realize that not all siblings from a single sac display the same traits. I've raised siblings side by side in identical enclosures with identical care and had one be super mellow and one be super defensive. That takes the nature vs nurture aspect of the situation out of my immediate equation.

P.S.
I hope this long and rambling post made some sort of sense. It's way too early in the morning to be contemplating tarantula genetics which only shows exactly how much of a nerd I am.

 

[Jpeg]

In humans personality is something like half nature, half nurture. i.e., identical twins raised in different environments will have similar traits to a high degree of significance but are also heavily impacted by experiences which one twin had and the other did not. It's not unlikely tarantulas are similar. They don't have the intelligence to consciously learn from their environment but there's no reason to think they can't be pressured to react one way over another. Daphnia grow spikes and armor in the presence of certain predators and they're far simpler than tarantulas; it seems a relatively smaller change to go from "bite less" to "bite more." Of course since they're also affected by nature slings from the same sac would have varying traits.

 

[EulersK]

I think that, for once, this is actually easier to answer (and speculate) than what we normally do.

Just like with everything else, chemical processes (such as metabolism and neuroreceptors) have a genetic influence. But, also like with everything else, that's not the whole story. We know that outside forces can influence things like temperament and metabolism. Take a litter of cats for example. In the womb, they very much look like two packages of hot dogs next to each other. If you have a female with a male on either side of her, then that cat will most likely have a temperament closer to a male than a female. Conversely, if you have a female cat with another female on either side of her, then she will have the textbook female temperament. This is because of the proximity to sexual hormones in the womb. Of course, spiders do not develop in the womb nor share nutrients, but the point stands that outside factors affect temperament.

It does stand to reason that hormone levels are passed on through genetics (because they simply must be, that's how reproduction works), so the slings will have a baseline temperament based on their parents. But we know so little about their development, meaning that anything from temperature to order of fertilization could affect how the hormones are influenced.

And because I'm sure people will jump on hormone levels (and therefore temperament) being passed on genetically, we can prove this quite easily. Look at the case of P. murinus. They aren't taught to be so defensive and willing to bite, that must be instinctual... but instincts are driven by hormone levels and neurological structure. The same can be said with B. albopilosum's unwillingness to bite. So, we know that this is genetic. As a thought experiment, it would be interesting to think about the offspring of a P. murinus x B. albopilosum pair. Which parent would they favor? Would some slings be defensive and others docile? Would they all be in a happy middle ground?

 

[boina]

I think that, for once, this is actually easier to answer (and speculate) than what we normally do.

Just like with everything else, chemical processes (such as metabolism and neuroreceptors) have a genetic influence.
...

Which parent would they favor? Would some slings be defensive and others docile? Would they all be in a happy middle ground?

*chemical processes (such as metabolism and neuroreceptors) have a genetic influence.*

Er... No. Simply no. I'm molecular biologist and I work in cancer genetics and this is not how genetics work. It's the other way round. Genetics influence metabolism etc., but metabolism can not affect genetics. If you are talking about Epigenetics - and it may be that that's what you were thinking about - it's really not as simple as that. Metabolism and neuroreceptors will change the expression of certain genes, but not the genetic setup itself. Now, under certain circumstances, which are actually not all that common, epigenetic modifications (and they are modifications, not alterations and as such are reversible) may be passed onto the next generation, but we really don't know enough about that to make statements like the above.

*Would some slings be defensive and others docile*

No, they wouldn't. 1. Generation (F1) is always pretty much the same. They may be ALL aggressive, or ALL docile, or ALL intermediate, but if it's genetic they will be all the same. They should get one chromosome from father and one from mother - all of them. Now if you interbreed the F1 generation the F2 generation can vary quite a lot. (Mendelian Genetics)

 

[Sana]

I'm thinking along the lines that if I pair my completely insanely defensive P. regalis with an equally defensive male will I end up with a royal headache on my hands? Following that is I pair the same female with an incredible calm and easy going male will the resulting headache be less? And assuming that I ever came across both an incredibly calm male and female and paired them would the most likely outcome be a higher percentage of relatively mellow slings in the sac?

 

[EulersK]

Er... No. Simply no. I'm molecular biologist and I work in cancer genetics and this is not how genetics work. It's the other way round. Genetics influence metabolism etc., but metabolism can not affect genetics.

Poor wording on my part - that's actually exactly what I meant.

However, the second part isn't necessary true. It's a wildly simple example, but pairing a NCF H. incei with a GCF H. incei can very well result in 50/50 GCF and NCF offspring. Yes, that's only one allele at work, but the point stands.

 

[boina]

Poor wording on my part - that's actually exactly what I meant.

However, the second part isn't necessary true. It's a wildly simple example, but pairing a NCF H. incei with a GCF H. incei can very well result in 50/50 GCF and NCF offspring. Yes, that's only one allele at work, but the point stands.

Yes, but in pairing H. incei NCF and GCF you are talking about technically an F2 setting. I said they could vary a lot. So, let's consider GCF dominant, just for the sake of argument. So your GCF can actually carry 1 GCF and one NCF allele. So you get:

GCF-NCF (GCF looking) x NCF-NCF (obviously NCF looking) -->
25% GCF-NCF (GCF) +
25% GCF-NCF (GCF) +
25% NCF-NCF (NCF) +
25% NCF-NCF (NCF)
(I underlined one NCF just to indicate the different alleles)
makes 50/50.

This doesn't work in the setting you proposed above, because P. murinus must have 2 defensive alleles (lets call them D) (because otherwise you'd regularly (25% at least) get docile P.m.s) and B. albopilosum must have two docile alleles (lets call them d), because otherwise you'd regularly (25% at least) get defensive Albos. So you get:

D-D x d-d --> D-d
Nothing else is possible. Whatever they are, they are the same.

 

[boina]

I'm thinking along the lines that if I pair my completely insanely defensive P. regalis with an equally defensive male will I end up with a royal headache on my hands? Following that is I pair the same female with an incredible calm and easy going male will the resulting headache be less? And assuming that I ever came across both an incredibly calm male and female and paired them would the most likely outcome be a higher percentage of relatively mellow slings in the sac?

I absolutely don't know. But if you try it, can you please post the results? I'd love to know haow it works out

 

[boina]

I'm thinking along the lines that if I pair my completely insanely defensive P. regalis with an equally defensive male will I end up with a royal headache on my hands? Following that is I pair the same female with an incredible calm and easy going male will the resulting headache be less? And assuming that I ever came across both an incredibly calm male and female and paired them would the most likely outcome be a higher percentage of relatively mellow slings in the sac?

I absolutely don't know. But if you try it, can you please post the results? I'd love to know haow it works out

 

[EulersK]

Yes, but in pairing H. incei NCF and GCF you are talking about technically an F2 setting.

I don't quite see how that's an F2 setting, could you elaborate?

But of course, this is all assuming a single allele... which is almost certainly not the case.

 

[boina]

I don't quite see how that's an F2 setting, could you elaborate?

But of course, this is all assuming a single allele... which is almost certainly not the case.

No, it's probably not a single allele or even a single gene. But even if it's a set of different genes interacting the resoning would be the same: P. murinus on one side should have all the alleles for *defensive* while B. albopilosum should have all for *docile*.
Example: In Germany in the 1980s they crossed large Poodles with wolves (honestly!) for exactly this purpose: to see how behavior would be passed on, what was genetic and what was nurture. The F1 generation all looked and behaved pretty much the same: large black dogs with hanging ears, a bit like large hunting dogs and not at all how you'd imagine a wolf mix. The behavior was intermediate.
What you are proposing is pretty much the same: Cross two genetically distinct species. And that's pretty much the definition of an F1 generation. Or at least cross two forms that are genetically distinct in both alleles of a specific gene locus, like Mendel and his peas.
Now H. incei NCF and GCF are not exactly genetically distinct species. They are color forms of the same species. I think GCF is a mutation? But I'm not sure here, I don't know enough. Anyway, they share one allele and therefore do not fulfil the criteria for an F1 breeding.
Was that in any way understandable? It's a bit late around here and I'm not sure I'm still being so clear.

 

[Sana]

I absolutely don't know. But if you try it, can you please post the results? I'd love to know how it works out

Well darn. I was sort of afraid that was going to be the answer somewhere down the line of this discussion. I don't have the ability (space, time) to raise multiple sacs to maturity for research purposes. The best I can do is keep track of observations for various specimens and their offspring and maybe get together enough information to theorize the role of genetics in tarantula temperament. Maybe some other folks will be interested in joining in with their experiences and sacs as well. I suppose once we have a basic idea we could try to get together something more serious and fitting to a proper format for a study. We have a number of professionals in various fields of scientific studies that might be willing to spend some time helping set up something in a more acceptable format.

 

[viper69]

Color is for sure, N incei Normal vs Gold color/pattern forms perfect example, same species.

Behavior-- No one has a clue.

 

[Bugmom]

Personally, I don't believe that tarantulas are evolved enough for "behavior" and "temperament" to be something we can manipulate through selective breeding. Simply put, I think there's literally not enough genetic material to work with. Tarantulas are, as much as I love them, incredibly simple creatures. The roaches I feed to them are geniuses compared to the spiders. I think you'd have about as much luck breeding for "docile" or "reactive" Ts as you would trying to change the temperament of cobras. From the reading and research I've done, some animals cannot be domesticated, period. I think tarantulas are one of them. Even the 50-year Siberian fox experiment resulted in a "pet" fox that was somewhere between a dog and a cat in terms of loyalty and love displayed towards humans. At no point did the foxes become domesticated and tame like modern dogs are.

 

[Jpeg]

Even the 50-year Siberian fox experiment resulted in a "pet" fox that was somewhere between a dog and a cat in terms of loyalty and love displayed towards humans. At no point did the foxes become domesticated and tame like modern dogs are.

Oh boy yes they did though. They were the so called "Elites."