Were Tarantulas effected by tectonic plates?

[AmbushArachnids]

I thought this would be a stimulating topic. I was recently talking with a friend about earthquakes here in WA. If Ts are as old as dinosaurs does it make scense that certain genera of Ts could be spread around to different areas of the world by continental drift? Of course they make have evolved so much we would never know. Just a cool thought i had that id like to share. If this is possible, could there be evidence of this in the hobby today? :? I havnt done any research but i thought i would share this topic for the knowledge thristy.

-Doug P.

 

[JimM]

I think your understanding of the word 'genera' is a bit flawed.
Movement of the plates caused divergence within the family, but not within individual genera. The span of
time that we're talking about is just too great.

If you do some research you'll note that almost any family you
look at has close cousins across the ocean.

If you're looking at any given genus (plural, genera) they've by now evolved
a bit differently from their relatives in the same family on other continents.
If you have something that has "evolved so much we would never know" then you're no longer looking at something within the same genus at all, since by definition the constituent members of the genus share most of the same attributes, characteristics, morphology.

A mountain lion and a tiger obviously share the same lineage, but due to geographical isolation (and you'll note neither is "as old as the dinosaurs") they have diverged somewhat. So while a tiger, a lion and a leopard are all members of the genus Panthera, a mountain lion, seperated by an ocean, is of the genus Puma.

Same with tarantulas. We have the family Theraphosidae covering a very wide range throughout the world, due to continental drift as you elude. However the individual genera are much more localized. Again, geographical isolation at work. We have Hysterocrates and Poecilotheria limited to the Old World, and Brachyphelma, Avicularia limited to the new world, even though they share a common lineage.

 

[AmbushArachnids]

I think your understanding of the word 'genera' is a bit flawed.
Movement of the plates caused divergence within the family, but not within individual genera. The span of
time that we're talking about is just too great.

I understand the word genera just fine. I note that some Tarantulas in different locations share the same genus such as avicularia sp. and psalmopeous. I was curious if any remote locations such as islands that have drifted far apart from the coast carry a same genera from a mainland. The big difference i guess would be spieces. Is it safe to say that all spieces of a genus came from a similar ancestor? I would think so.

I found my answer and i think it proves your text in red to be incorrect: One example is Sri Lanka. It is an island but inhabits the genus Poecilotheria. Poecilotheria also inhabit india. Of course tectonic plates are what separated them.

My main question is: Is there evidence we can see in Tarantulas being closely related to one another from coasts that used to connect. Such as africa, Australia and brazil. North amarica and china. :?

 

[FrogEyes]

Poecilotheria is assigned to its own subfamily, Poecilotheriinae, which is essentially confined to the Indian subcontinent. That INCLUDES Sri Lanka. Likewise, Harpactirinae is essentially African, Ornithoctoninae is Asian, Theraphosinae is American, etc. There's the proof you're looking for. Theraphosidae arose prior to Gondwana rifting apart, and the genera or clusters of related genera in different regions became isolated from one another for many millions of years, continuing to evolve to a point at which a number of new species and genera arose in each area. We now recognize each of these divergent groups as subfamilies, when each may have arisen as a single species.

That's not the end of the story. Continental drift doesn't just break continents apart - it also slams them together. Thus, formerly isolated subfamilies from different regions come into contact again, and regional specialties invade new regions.

Rafting also allows spiders [and anything else] to arrive at new locations, such as islands, without continental drift playing a role. The simple fact that some species occur on islands does not necessarily have anything to do with rifting or tectonics. Sri Lanka is essentially just an isolated portion of the Sahyadra Mountains of western India. The Galapagos, Canaries, and Hawaiian Islands were all formed in isolation by volcanic activity. Madagascar and Seychelles, however, are essentially isolated mini-continents which shattered away as India separated from Africa. That's why these regions tend to have local peculiarities whose closest relatives come from the other regions. Rhacophoridae is mainly Asian, but its closest relative is the Madagascan Mantellidae. Indian Nasikabatrachus is unique, but is closest to Seychellean Sooglossus.

I was curious if any remote locations such as islands that have drifted far apart from the coast carry a same genera from a mainland.

For the most part, islands do not arise by rifting. They come about by volcanic activity, coral growth, changing sea levels, and erosion. Those which HAVE rifted, are often erosional remnants of much larger landmasses. The larger mass typically rifts away, and is gradually broken down by other forces until it forms the smaller islands now seen.

The big difference i guess would be spieces. Is it safe to say that all spieces of a genus came from a similar ancestor?

If not, then they do not belong to the same genus. One of the primary purposes of scientific names is to reflect relationships. A scientific name of any type should include ALL descendents of one ancestor, whether that be a genus, family, class, etc. Species follow slightly different standards, so ignore that for now.

I found my answer and i think it proves your text in red to be incorrect: One example is Sri Lanka. It is an island but inhabits the genus Poecilotheria. Poecilotheria also inhabit india. Of course tectonic plates are what separated them.

The first and last sentences quoted are both incorrect, for reasons already outlined.

My main question is: Is there evidence we can see in Tarantulas being closely related to one another from coasts that used to connect.

Yes. Not so much for "closely related", since much of the evolution is ancient. That's why different subfamilies of tarantulas are restricted mainly to particular modern continents. SOME subfamilies include forms which have managed to colonize other regions by crossing water, and a couple subfamilies are artificial - their members aren't actually related to one another. That's a problem to be worked out still, and will result in some subfamilies disappearing, new ones possibly being named, or their members being split up among other subfamilies.

 

[Bill S]

Excellent answer, FrogEyes. I'll add that there are climatic changes that cause fragmentation and speciation as well. As an example from my region(using scorpions rather than tarantulas) - the Tucson Valley was an evergreen forest back during the Pleistoscene. Much wetter and greener than it is today, and the forest habitat was contiguous. But starting about 10 to 12 thousand years ago there was a climate shift that turned the lower elevations into the desert that it is today. The forest basically retreated up the mountains and now consists of "sky islands" of isolated forest surrounded by a sea of desert.

A species of forest scorpion (Vejovis vorhiesi) was widespread throughout the area, and retreated into the sky islands along with the forest. And some populations retreated into caves at lower elevations to escape the drying heat. Some of those isolated populations have started to differentiate into new species.

 

[boonbear]

your thinking of something similar to the tiger snake in Australia, where on an island off the coast, has turned black and developed a MUCH higher toxin, but is still just a tiger snake. Is that similar to what you mean?

 

[AmbushArachnids]

Poecilotheria is assigned to its own subfamily, Poecilotheriinae, which is essentially confined to the Indian subcontinent. That INCLUDES Sri Lanka. Likewise, Harpactirinae is essentially African, Ornithoctoninae is Asian, Theraphosinae is American, etc. There's the proof you're looking for. Theraphosidae arose prior to Gondwana rifting apart, and the genera or clusters of related genera in different regions became isolated from one another for many millions of years, continuing to evolve to a point at which a number of new species and genera arose in each area. We now recognize each of these divergent groups as subfamilies, when each may have arisen as a single species.

That's not the end of the story. Continental drift doesn't just break continents apart - it also slams them together. Thus, formerly isolated subfamilies from different regions come into contact again, and regional specialties invade new regions.

Rafting also allows spiders [and anything else] to arrive at new locations, such as islands, without continental drift playing a role. The simple fact that some species occur on islands does not necessarily have anything to do with rifting or tectonics. Sri Lanka is essentially just an isolated portion of the Sahyadra Mountains of western India. The Galapagos, Canaries, and Hawaiian Islands were all formed in isolation by volcanic activity. Madagascar and Seychelles, however, are essentially isolated mini-continents which shattered away as India separated from Africa. That's why these regions tend to have local peculiarities whose closest relatives come from the other regions. Rhacophoridae is mainly Asian, but its closest relative is the Madagascan Mantellidae. Indian Nasikabatrachus is unique, but is closest to Seychellean Sooglossus.


For the most part, islands do not arise by rifting. They come about by volcanic activity, coral growth, changing sea levels, and erosion. Those which HAVE rifted, are often erosional remnants of much larger landmasses. The larger mass typically rifts away, and is gradually broken down by other forces until it forms the smaller islands now seen.


If not, then they do not belong to the same genus. One of the primary purposes of scientific names is to reflect relationships. A scientific name of any type should include ALL descendents of one ancestor, whether that be a genus, family, class, etc. Species follow slightly different standards, so ignore that for now.


The first and last sentences quoted are both incorrect, for reasons already outlined.


Yes. Not so much for "closely related", since much of the evolution is ancient. That's why different subfamilies of tarantulas are restricted mainly to particular modern continents. SOME subfamilies include forms which have managed to colonize other regions by crossing water, and a couple subfamilies are artificial - their members aren't actually related to one another. That's a problem to be worked out still, and will result in some subfamilies disappearing, new ones possibly being named, or their members being split up among other subfamilies.

Thanks for the insight.

 

[Irfin]

If you're not a geological evolutionary biologist I would leave speculation to those who are professionals. No one here has the scientific background to answer such a big picture question. I expect a fall out of pseudo-scientific opinion. AKA a lot of people pretending to know more than they really do. Good luck.

 

[Toirtis]

If you're not a geological evolutionary biologist I would leave speculation to those who are professionals. No one here has the scientific background to answer such a big picture question. I expect a fall out of pseudo-scientific opinion. AKA a lot of people pretending to know more than they really do. Good luck.

But FrogEyes is up there, and as close as you are going to get on here.

 

[JimM]

If you're not a geological evolutionary biologist I would leave speculation to those who are professionals. No one here has the scientific background to answer such a big picture question. I expect a fall out of pseudo-scientific opinion. AKA a lot of people pretending to know more than they really do. Good luck.

Arrogant post of the week.
Agent's question (while not worded very well) was not that "deep", and the info is nothing that can't be gleaned from paying attention as one goes through life keeping and learning about wildlife or the earth in general.

Guess what, it's possible to pay attention in college in certain classes even if you're not perusing that exact degree, or research and read on your own outside of school and have your S together on any given subject if you have the grey matter to process it.

I can talk your ear off about a few subjects that I didn't actually obtain a degree in, and the same can be said for a few people here on the board as well regarding various things.

I've had to correct PhD's regarding questions of varanid and piscine behavior in the past, on more than once occassion...guess what my college degree is in? Illustration. This hasn't stopped me from educating myself about, and being published in other arenas.

I could have used the family Cichlidae to provide yet another analogy with regard to agent's question, as could anyone who's sufficiently educated themselves about these fishes. Evidence of various families being represented in the old and new world, their similarities and divergence abound.

This post isn't about me, just using myself as an example since I don't have the detailed knowledge on other members to use them instead. I do know that my post applies to a few other members here, regardless of what piece of paper they chose in school.

Your post contributed nothing to the conversation here, and as it turns out was erroneous if not totally uncalled for.
Regards