Science of “Semi-Arboreal”

[YungRasputin]

I want to attack this subject from a scientific perspective and was hoping AB could help me out here - i think the general consensus here is that such a category doesn’t exist and this is what I would like to prove objectively

also tagging @AphonopelmaTX since they’re real good with this

 

[Smotzer]

There are species that are highly adaptable, these often are the ones deemed “semi arboreal”, but semi arboreal as a discrete type I have not seen, just species that are highly adaptable IME.

 

[YungRasputin]

There are species that are highly adaptable, these often are the ones deemed “semi arboreal”, but semi arboreal as a discrete type I have not seen, just species that are highly adaptable IME.

that’s an issue i think is good for discussion - earlier today i was arguing that documented wild behavior of P. murinus can not be described as arboreal insomuch as i haven’t seen anything which would substantiate said claim

sources provided in those discussion and the ones I’ve had on AB have shown that they will sometimes make dens in scrub vegetation, low level debris such as dead tree trunks, etc - this however doesn’t seem to be within the umbrella of arboreal

there was a video in which it was that they created dens within a mountain slope but I also don’t think that’s arboreal behavior either since a) within the wild the create burrow at the crevice points within those slopes and b) in captivity, in my experiments with this set up, my OBT-UMV has exhibited identical behavior, creating a burrow den from a crevice point in the enclosure’s slope

i also think, per adaptability, that the utilization of vertical spaces is still within the realm of what’s terrestrial - behaviors of this sort seem to indicate that they’re more solid in climbing than some other terrestrial (NW) species - but - what i would also like to know, do these “semi-arboreal” species have the same physical adaptations that arboreal species have which facilitates their climbing

or conversely, do these “semi-arboreal” species have or lack, physical adaptations which facilitate burrowing eg: stocky to thick back legs and the like

 

[viper69]

I want to attack this subject from a scientific perspective and was hoping AB could help me out here - i think the general consensus here is that such a category doesn’t exist and this is what I would like to prove objectively

also tagging @AphonopelmaTX since they’re real good with this

See my post some time ago on GBB from a biologist who studies them in the wild.

GBBs most definitely do not have adaptations like Pslamo and Avic. Perhaps one could argue their slim body is an adaptation but I don't believe it.

 

[Smotzer]

that’s an issue i think is good for discussion - earlier today i was arguing that documented wild behavior of P. murinus can not be described as arboreal insomuch as i haven’t seen anything which would substantiate said claim

sources provided in those discussion and the ones I’ve had on AB have shown that they will sometimes make dens in scrub vegetation, low level debris such as dead tree trunks, etc - this however doesn’t seem to be within the umbrella of arboreal

there was a video in which it was that they created dens within a mountain slope but I also don’t think that’s arboreal behavior either since a) within the wild the create burrow at the crevice points within those slopes and b) in captivity, in my experiments with this set up, my OBT-UMV has exhibited identical behavior, creating a burrow den from a crevice point in the enclosure’s slope

i also think, per adaptability, that the utilization of vertical spaces is still within the realm of what’s terrestrial - behaviors of this sort seem to indicate that they’re more solid in climbing than some other terrestrial (NW) species - but - what i would also like to know, do these “semi-arboreal” species have the same physical adaptations that arboreal species have which facilitates their climbing

or conversely, do these “semi-arboreal” species have or lack, physical adaptations which facilitate burrowing eg: stocky to thick back legs and the like

Pterinochilus murinus is a prime example of high adaptability, if all color forms truly are the same species, the species has adapted across a great range of area with different available types for habitation. This includes underground, in vertical rock crevices, crevices in trees. I still would not classify that as semi-arborea just highly adaptable. They are not arboreal as say Aviculariinae are.

 

[YungRasputin]

See my post some time ago on GBB from a biologist who studies them in the wild.

GBBs most definitely do not have adaptations like Pslamo and Avic. Perhaps one could argue their slim body is an adaptation but I don't believe it.

someone tried this with OBT (slim body) however I’m not seeing how the OBT’s body differs from that of its fossorial sister species, like P. Lugardi, etc or, for that matter, resembles arboreal baboon species like S. cal, H. mac, E. olivacea, etc

i figure this is the same case with GBB

 

[DomGom TheFather]

I know i say it a lot but this ain't nature.
What we do is put a spider in a box.
Tall enclosures are for arboreal species.
If they don't live in trees, you drop down the peg and set up for terrestrial living. Deep sub goes to the obligate burrowers. And so on. There's tons of wiggle room and it's more than fair play to explore what species will tolerate what conditions best in captivity. Doing your best isn't a crime. Just remember what we're working with are big fingers in small pies. Or maybe it's small fingers, big pies. Idk... Lost it.

 

[birdonfire]

They're probably just trying to catch water.

 

[viper69]

the species has adapted across a great range of area with different available types for habitation

One of the biggest mysteries to some arachnologists is how successful Avicularia has been covering S. America (not even mentioning versi). I was talking to one of these people, and s/he told me it's a big mystery as to how they became so successfully widespread.

 

[Smotzer]

One of the biggest mysteries to some arachnologists is how successful Avicularia has been covering S. America (not even mentioning versi). I was talking to one of these people, and s/he told me it's a big mystery as to how they became so successfully widespread.

Could colonization play a role in the dispersal of them?

 

[viper69]

Could colonization play a role in the dispersal of them?

This wasn't mentioned to me, and I doubt it myself too. These people are thinking along the lines of natural forces not related to man. These species were established long before colonial times.

 

[Smotzer]

This wasn't mentioned to me, and I doubt it myself too. These people are thinking along the lines of natural forces not related to man. These species were established long before colonial times.

Hmmmm I was just spitballing. What’s your hypothesis?

 

[viper69]

Hmmmm I was just spitballing. What’s your hypothesis?

I don't know, it's not my field.

 

[Smotzer]

I don't know, it's not my field.

Well yeah, but have any guesses? Sorry I can’t recall, but I was the revision phylogenetic? It’s been awhile since I’ve read it.

 

[viper69]

but have any guesses?

No haha, no means no, didn't they teach you that in school Or are we sending you off to sensitivity training

The revision was a classical cladistics paper IMO.

Wish it had DNA. She did a lot of hard/long work. I know someone that knows the author, and in come cases she raised slings.

 

[Smotzer]

No haha, no means no, didn't they teach you that in school Or are we sending you off to sensitivity training

The revision was a classical cladistics paper IMO.

Wish it had DNA. She did a lot of hard/long work. I know someone that knows the author, and in come cases she raised slings.

Okay that’s what I thought, a phylogenetic study would likely shed some needed light on this topic.

 

[viper69]

Okay that’s what I thought, a phylogenetic study would likely shed some needed light on this topic.

I could be wrong.

But I know DNA was not used. That was my biggest issue.

There’s more than a few Avics that I’d like to know if they are unique species or sub-species . Only DNA can tell us this.

 

[AphonopelmaTX]

I want to attack this subject from a scientific perspective and was hoping AB could help me out here - i think the general consensus here is that such a category doesn’t exist and this is what I would like to prove objectively

also tagging @AphonopelmaTX since they’re real good with this

Thanks for the compliment.

All semi-arboreal means is that a species of animal, or a population of a species, spends some of its life in the trees and other parts on the ground. A couple of examples I have come across of this is the chimpanzees and gorillas which nest and sleep in trees at night and carry out other activities on the ground during the day. Sleeping at night isn't the only activity they do in the trees, but the point is both great ape species don't have a distinct lifestyle they carry out exclusively in either. This is contrast to the orangutan or the monkeys which live exclusively, or at least carry out the majority of their daily routines, in jungle canopies which make them arboreal.

To my knowledge, no tarantula species have been found to be semi-arboreal. Those that live in the trees or on the ground do so exclusively. What semi-arboreal does not mean is when one population (or a few individuals) of a species are found living in a tree while others on the ground. When that occurs you describe it as one population exploiting whatever it has to in order to survive. Arboreal, semi-arboreal, and ground-dwelling are not exclusive categories for all species of tarantula either. Life just does not like to fit into nice categories for us to use. For example, the species Pachistopelma bromelicola, which live in the leaves of bromeliad plants, isn't technically arboreal (they don't live in trees), semi-arboreal (again they don't live in trees), or found in or on the ground exactly. They successfully exploited a very specific niche in their native habitat which has aided in their survival.

Okay that’s what I thought, a phylogenetic study would likely shed some needed light on this topic.

The revision of the genus Avicularia was, in fact, a phylogenetic study using cladistic analysis as the method to which a hypothesis of the evolutionary relationships of the taxon was arrived at. The cladistic analysis used only morphological characters because the authors used the morphological species concept as the definition of a species. There are many definitions of a species.

A phylogenetic study seeks to understand the evolutionary relationships between a group of similarly related organisms.

A cladistic analysis is a method of finding evolutionary relationships by analyzing how characters determined by the taxonomist are similar, different, ancestral, derived, etc.. A cladistic analysis can use any number of characters including physical (genitalia is used more often and most reliably in spiders), molecular (DNA and RNA), behavior, or a combination of such. Since the morphological species concept is used most often in cladistic analyses in spiders, you don't see molecular or behavioral characters used very often.

 

[DaveM]

To my knowledge, no tarantula species have been found to be semi-arboreal. Those that live in the trees or on the ground do so exclusively. What semi-arboreal does not mean is when one population (or a few individuals) of a species are found living in a tree while others on the ground. When that occurs you describe it as one population exploiting whatever it has to in order to survive. Arboreal, semi-arboreal, and boreal (ground dwelling) are not exclusive categories for all species of tarantula either. Life just does not like to fit into nice categories for us to use. For example, the species Pachistopelma bromelicola, which live in the leaves of bromeliad plants, isn't technically arboreal (they don't live in trees), semi-arboreal (again they don't live in trees), or boreal (they are not found in or on the ground exactly). They successfully exploited a very specific niche in their native habitat which has aided in their survival.

Very nice answer @AphonopelmaTX

One small, nitpicky question: I've never seen the term boreal used that way. For organisms that live on the ground, we could call them ground-dwelling, terrestrial, or terricolous.
Boreal means northern -- from Latin borealis "northern" -- from Greek mythology Boreas, the god of the cold northern wind and the bringer of winter. Boreal contrasts with austral (Latin australis "southern"). Am I missing some additional alternative definition?
I think arboreal (Latin arbor/arboreus "tree/tree-like") is a false cognate of boreal, that the two words are not etymologically related, which could easily have caused confusion somewhere.

 

[AphonopelmaTX]

Very nice answer @AphonopelmaTX

One small, nitpicky question: I've never seen the term boreal used that way. For organisms that live on the ground, we could call them ground-dwelling, terrestrial, or terricolous.
Boreal means northern -- from Latin borealis "northern" -- from Greek mythology Boreas, the god of the cold northern wind and the bringer of winter. Boreal contrasts with austral (Latin australis "southern"). Am I missing some additional alternative definition?
I think arboreal (Latin arbor/arboreus "tree/tree-like") is a false cognate of boreal, that the two words are not etymologically related, which could easily have caused confusion somewhere.

No, you didn't miss an alternative definition of boreal. I defined it incorrectly and corrected my post based on your input. Thank you for providing the correct definition and being tactful and polite in doing so.