Avicularia versicolor...small/large forms ?

[lynn mawdesley]

Okay so ive been in the hobby for '5 mins' a year in fact! since been in this hobby ive come across numerous ppl say they are 2 forms...been 'large' & 'small'?
What has been mentioned are different colours and size!
He said this she said that?
Now what i do want to know ...and this will be copied over another two forums is ...... who has the hard evidence to say there are 2 forms? ....which taxonamist is dealing with this for the ppl to justify that there is infact 2 forms?

Lynn

[Nicola Dolby]

I've never heard of their being two forms Lynn. However Avics can grow to strange sizes. I have heard of metallica males maturing at 9cm legspan yet mine grew to 14cm before maturing. I also have had a female purpurea for nearly 2 years and she still hasn't got into double figures with the size! Good luck!

[Phil Rea]

Can.of.worms.

Have a look at the Avic thread on T-store, and you'll see what a tangled mess Avicularia spp. are in at the moment. I have no idea if a revision is being worked on, but if it is, then I deeply respect whoever is prepared to take on such a mammoth task.

Personally I blame Linnaeus for describing the first one in 1758 (Aranea avicularia, now Avicularia avicularia)

[Søren Rafn]

Sorry for cross posting my reply from the T-store but the questions is a cross post as well, so I guess it's ok

Maybe it will help to understand that forms are very real entities. Forms are merely another word for variations. In biology we see both variations between specimens within a regional population and also between regional populations. This is not neccesarily indicating different species but provided that the barriers (rivers, mountains, sea, shift in biotope, altitude etc.) between two populations are sufficient to seperate them for long enough we may be seeing the beginning of a speciation event in the subtle regional differences within a species. All well understood due to the thory of evolution.

So when we are talking about two discreete populations of one species from two isolated islands I would be more surprised if the forms were similar!

We have a tendency to see tarantulas in the hobby as very discreete species that are very uniform. And the hobby populations definitely tend to confirm this notion for a big number of species. Basically because the hobby populations has originated from very few individuals - sometimes only one pregnant female - from one locality. For instance L. parahybana, A. geniculata, P. rufilata etc. But also because many existing descriptions are based on one specimen of each sex from one locality and not representative series of variations from different locations.

If a wider sampling (both in the collecting for the hobby and the science) had occurred which had defined the maximum spread area of a given species in nature and secured a larger number of specimens from different parts of the spread area we would see a higher rate of variation. I believe this is also basis on many of the heated discussions about forms of different species on this and other fora. Again because we are basically line-breeding geographic populations or distinctive varieties. And nothing wrong with that. Actually I prefer to keep regional varieties clean.

Long mail - but the conclusion is that if we have different island populations of A. versicolor in the hobby we should expect variations in morphology between the specimens from the different populations and not uniformity. Though - if not all that are breeding this species are aware of this, then uniformity of the hobby population will be the result and we will have a hobby population (and even hobby population variations) which is not representative of any natural populations ...

Regards
Søren

[Phil Rea]

That was a close one Søren. I nearly deleted your other post as a duplicate when you were deleting the first one

I am a great believer in keeping regional forms separate, but I think the problem is that the hobby isn't routinely told where the populations originate from.

Buy a versicolor from one dealer, and it's a versicolor. Buy or get another male 'versicolor' from somewhere else, breed them, and you could have unintentionally bred two forms.

It's bad enough with certain dealers labelling stuff differently e.g. I've seen the same spider sold as Augacephalus sp. 'mozambique', Augacephalus junodi , and now one dealer is selling them as the species that they are being transferred to before publication of the paper.

[Richard Gallon]

The captive gene pool of Avicularia versicolor comprises spiders from three different islands: Martinique, Guadalope and Dominica. Unfortunately, as far as I know, nobody kept these lines separate, so they are intermixed in captivity and have been for some time.

Guadalope and Martinque populations were said to differ in size, but I don't remember which island held which size.

Cheers,
Richard

[Søren Rafn]

I am a great believer in keeping regional forms separate, but I think the problem is that the hobby isn't routinely told where the populations originate from.

Buy a versicolor from one dealer, and it's a versicolor. Buy or get another male 'versicolor' from somewhere else, breed them, and you could have unintentionally bred two forms.

I think you are right that the forms should be labelled or recorded in a way as to keep the different forms seperate. Whether this be by locality, naming or numbers. This is pretty straight forward. But for this to be of any use there are a number of other factors that need be in place which it has proven very difficult to establish.

First and foremost an understanding of what is considered a species (many definitions ...) and why varieties has relevance to this concept.

This requires at least a basal understanding of how evolution works and why modern systematics are based on this concept.

Also a firm ability to seperate the distinction between inter-population variations and variations between different regional populations of a species... not to mention differences between actual species ...

Some sort of knowledge or agreement about that there is a difference ...

Willingness to pass on a breeding opportunity if the mating pair are from different populations or their pedigree is unknown...

These above can lead to the appreciation and keeping of interspecific variation (forms) in the hobby and add to a sense of why it has any relevance to the breeding of any species.

And last it requires that even when all parameters are met we will have to accept that the hobby lines may not represent real natural populations after all. This is due to the fact that any man made breeding effort is not natural selection and tend to produce specimens adapted to our keeping conditions and aesthetics and thus tend to produce traits not found in nature... which at the end of the day renders all above pretty useless ...

Regards
Søren

[Phil Rea]

First and foremost an understanding of what is considered a species (many definitions ...) and why varieties has relevance to this concept.

Well, there won't ever be a clear definition of 'species' as far as I can see (or even really a consensus) within the biological community.

However if regional variations are clearly labelled, kept separate, and not interbred, then I guess that however you classify a species, it shouldn't matter.

These above can lead to the appreciation and keeping of interspecific variation (forms) in the hobby and add to a sense of why it has any relevance to the breeding of any species.

Interspecific or intraspecific?

And last it requires that even when all parameters are met we will have to accept that the hobby lines may not represent real natural populations after all. This is due to the fact that any man made breeding effort is not natural selection and tend to produce specimens adapted to our keeping conditions and aesthetics and thus tend to produce traits not found in nature... which at the end of the day renders all above pretty useless ...

I agree entirely. We also tend to keep alive genetically weak or suspect offspring in captivity because they receive the same artificial care as stronger specimens. Spiderlings that in all probability would have succumbed to predation or other forms of natural selection in the wild survive and go on to breed, and so further weaken the captive gene pool.

[lynn mawdesley]

So the only true way to clarify which form we have would for them to be imported from either of the 3 islands for them to be true lines.
As Richard said about nobody as far as he knows kept the lines seperate which would therefore suggest to me that what we all have in captivity are not true lines/ forms whatever you want to call them.
So people that are seperating the 2 forms small and large are proberbly a bit of both in the first place, so say if an eggsac is produced by a small form female out of them resulting slings is it quite possible that there could be large forms thrown back from the lines?

[Søren Rafn]

Well if you can locate one of the actual collectors and get offspring from him/her that are produced from wc parents, then your form is pretty likely to be pure. But just one generation or two generations away the likelihood of the forms being pure rapidly deteriorates unless you can be sure that the breeding has been exclusively inbreeding.

Bottomline is that if one is interested in breeding as pure forms as possible then it is not a bad idea to track the pedigree of the animals in question. Both for the sake of one self, but in particular for the sake of the breeders trying to keep forms pure as just one male (let's say of form "A") erroneously labelled as form "B" will throw a spanner in the collecting breeding efforts of all breeders trying to breed pure forms.

But in essence - yes - wc with good collecting locality is the best guarantee of form - and inbreeding of that import the only way to keep that hobby form relatively close to the original regional form.

Regards
Søren

So the only true way to clarify which form we have would for them to be imported from either of the 3 islands for them to be true lines.
As Richard said about nobody as far as he knows kept the lines seperate which would therefore suggest to me that what we all have in captivity are not true lines/ forms whatever you want to call them.
So people that are seperating the 2 forms small and large are proberbly a bit of both in the first place, so say if an eggsac is produced by a small form female out of them resulting slings is it quite possible that there could be large forms thrown back from the lines?