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Discussion in 'Field Trips (Natural Habitats)' started by Brent H., Aug 12, 2007.
Finally, an American who thinks like those European hobbyists!!! :clap:
I am sorry for posting this because it will probably be seen as ignorance but if what you need is associate DNA with morphological characteristiques and geographic location wouldn't it be easier, saving a lot of T's for you to collect data in the field, as this would allow to just sample one leg and keep them on their environment, describing the t morphology or using digital imaging.
And what do you expect to find out with this study really relevant to the T's benefit, besides your post doc project?
I have considered these approaches, and if it was feasible, that's the way I would do it. This far transcends just a "postdoctoral research project"; in fact, this is the impetus of a major effort to revise these spiders so we can have some baseline information on what to do next!
DNA sequences need to be associated with an actual specimen in order to preserve scientific rigor (once again, something that has been lacking in theraphosids). Other researchers need to have access to the specimens. And while some fantastic digital imaging equipment is available and would be extremely useful in the field, I cannot transport a scanning electron microscope out there for much of the other work that would need to be done. Not to mention, even the finest digital imaging equipment is no substitution for the actual specimen.
Without going into a lot of detail, we really cannot begin to preserve species (or any conservation units, be it populations, evolutionary significant units, lineages, etc.) until we know what is there, period. We need to know what species are out there before we can protect them -- that is plain logic, you cannot protect what does not exist (we can define existence as something that we know about). Species boundaries, distributions, variation, etc. all need to be documented in a scientific manner and made available to other researchers and the public in order for us to make INFORMED decisions. In a perfect world, there would be no habitat destruction or over-harvesting or whatever. But, we all contribute to the pressures placed on other species, either directly or indirectly. Nobody would argue that losing species or populations is a good thing. But, we sometimes have to make harsh decisions and face reality -- humans aren't going anywhere any time soon, and with increased growth, something will give. So, at least if we have data, we can make informed decisions about what to do next.
You personally might know of a local population that is very small and threatened from habitat destruction. However, who is going to make the decision to protect it without any information? Nobody! We need to identify units for protection based on what information we have at hand. If we have nothing, then nothing can be done.
I think people need to realize, too, that most North American tarantulas are probably doing just fine. Collecting a couple individuals from several locations across the USA will likely have no consequence on the long-term health of the populations. Some people on this discussion have made it sound like I am out to take anything and everything, and that is very short-sighted and ignorant. I do biodiversity research -- why? Because I like biodiversity, and I want to preserve these species so my fellow humans will have the opportunity to enjoy them as well. I keep spiders for the same reason everybody else does -- they are fascinating! But I also have a moral and scientific obligation to do my part in preserving these species. First, though, we need to know what we have... and that's what I'm doing!
i am pretty sure birds eat more tarantulas in a given area in a week than i could harvest in a year.
not to mention the parasitic wasps around here
you know what is the big risk to most native species? it is NOT overharvesting (that kind of makes me laugh, actually... *maybe* pocket species are at risk... but in general... no). it is habitat destruction! just like in the rest of the world.... humans are spreading like a plague across the face of the planet... tilling under and concreting over land as fast as possible... *that* is what is doing in species!
also, Brent... is your folding door spider paper(s) available anywhere? i love all the USA native myg's and am trying to learn as much as i can
I'm not in a position to be of any use to you, but I am curious about your DNA techniques. A dead spider, if frozen quickly after death, is infinitely useful for DNA purposes. We can get DNA from mice here which have been dead for a couple of weeks, and there was nothing more than a minus 20 freezer for storage (and I doubt it's even at -20 most of the time).
I'd also like to reinterate that "we don't kill for the sake of it" comment. We go through numbers of mice in my lab which disturb me, but there really isn't an alternative, and we really do go to great lengths as researchers to minimise the numbers we need.
As another technical note, do you need the whole leg? What are you using to extract the DNA? I would have thought that you can get away with MUCH less than that. We use about 5mg of tissue in this lab, and that tends to swamp our extraction method.
Best of luck, dude! (oh, and Congrats on the Ph.D. You got yours about a month before me!)
If you take part of a leg the spider will throw it off since its of no use to him anyway. The leg will regenerate during the following molts.
I have been able to get DNA from dead tarantulas (especially if they are immediately frozen after death), but I prefer live for a few reasons: (1) for digital imaging/live habitus shots; (2) I don't like dead animals (who does?); (3) behavioral observations; and (4) I don't like dead animals.
I generally harvest an entire leg as a tissue sample for three reasons: (1) I can have plenty of DNA for my extractions; (2) I can have additional tissue in case something goes terribly wrong and I have to re-extract (e.g., contamination or confirmation of unexpected data); and (3) I can voucher some tissue in a museum collection. A tarsus from a reasonable sized tarantula is more than enough tissue for my extractions, but tarantula legs are built to autotomize at the C-T joint, so to reduce the possibility of a torn appendage (and the potential for the spider to bleed to death), I take the whole thing. It'll grow back. I have read about a procedure that mildly anesthetizes the spider with CO2 and draws DNA from some hemolymph oozing from a punctured leg joint, but you still run the risk of "over doing" it, potentially killing the spider. It's easier on me and the spider to just take a leg. Exuviae don't provide the DNA yield necessary for nuclear genes, but should be okay in some cases to get mitochondrial DNA. I will toy with that in the future.
And congrats on your Ph.D. as well! I know it was hard-earned, Doctor!
Check the website in my signature... The two 2005 papers are linked, I think, from that site, although the 2007 paper may only be available to journal subscribers. I don't manage that webpage, so there are a few things (like the Saudi Arabian paper) that are published and not linked. Send me your email addy and I can send them to you.
Fair enough. Sounds like you got it all well sorted. Best of luck!
Did you go straight to the bank and get them to change the details on your statements, Dr? I did. The novelty has worn off though!
HA HA HA! No, I never had the prefix added. I liked the title for about a month, but like you said, the novelty has worn off. I still consider myself a student... always will!
The tarantula keeping hobby and wild tarantulas can both be in existence. Most species on the lists nowadays seem to be captive bred. It seems some species are prone to overcollection and this is what I believe we both object to. I would suggest that most of the tarantula decline you are seeing, as with most animals, is due t habitat loss.
There's no doubt about that... in fragile habitats (e.g., montane areas), I would only take one or two individuals if I felt the populations were healthy. The majority of tarantulas in the USA, at least up to this point, are probably doing quite well. My preliminary data suggests that a number of these species are MUCH more widely distributed than originally believed. My biggest goal at this point is to document all of the species in the USA and try to delineate their distributions... it's too bad that more people are unwilling to contribute (but a huge thanks to those that have contacted me).
Hey Brent i think what your doing is GREAT.
I just found a male and have GPS co-ords, if I give you the cords can you check and see if you already have specimens from this area?
I dont want to send him if you already have enough from this area.
Do you still have the male available? I do not check this forum as often as I'd like, so I may miss replies (it's easiest to email me directly). Southern California is very important for addressing a number of questions, so I would be happy to receive anything from that area.