Unanswered (Arachnological) research questions

Scientific research produces more questions than answers (at least in my experience!), and a neat paper, project or field season often leaves us with a suite of new directions to take a research program. I wish I had more time to answer some of these questions, but reality sets in: curious questions that arise aren’t always feasible, or perhaps the timing isn’t right, or the ideas aren’t funded(able), or interest from students or collaborators isn’t there. I have come to the realization that perhaps I shouldn’t keep these questions in my head, but instead should write them down, publicly. Perhaps these ideas will generate ideas for others, point me to literature on these topics, or at the very least it will help me to refine and rethink these questions. After all, coming up with a good research question is certainly one of the more challenging parts of the research process, and improving a question starts with taking a stab at formalizing it on paper.

Disclaimers:

1) I did not do any kind of extensive literature search to see whether these questions have been tackled already.

2) I think many of these questions are rather poorly formed, which is perhaps why they have not yet been answered…

Ok, so here goes, and I will start* with a few questions with an Arachnological flare:

Do Linyphiidae spiders *really* show higher diversity at more northern latitudes? This is a classic biogeographic question, and there have been hints and ideas that Linyphiidae spiders (aka “micro sheet-web spiders”, one of the most diverse families of spiders, generally small-bodied, ground-dwellers) show a reverse latitudinal trend, with fewer species in temperate regions compared to the tropics. My own lab’s research certainly supports the claim that Linyphiidae spiders dominate diversity in the North, but are they really less diverse further south?  Although this question has been partially answered at large(ish) spatial scales, I think we need to go BIGGER to truly unravel this one, and it needs to be done with sampling methods that are really comparable (i.e., standardized), along a gradient that runs from the tropics towards the poles.

What is the relationship between fang “size” in spider species and their relative venom strength? This seems like an obvious question but has perhaps not been answered. I am curious about this because I know some “small-fanged” spiders (eg, some crab spiders in the family Thomisidse) can really pack a punch, and I have heard that some larger spiders have relativity mild venom, despite the size of their fangs. I am not sure how easy it would be to answer this one: the literature about venom is probably scarce for most species, and I’m not even sure how to test for “venom strength”, or to properly quantify fang size. This question would also have to be addressed with close attention to phylogeny.

 

Check out these fangs! (and venom…). Photo by Alex Wild

In the canopy of temperate, deciduous forests, where do the spiders come from? My lab has done a fair bit of work on canopy spiders, and their dispersal abilities, but I’m just not sure where spiders come from each spring. This is particularly relevant in my region because of the strong seasonality and harsh winters. I see three options: they colonize tree-tops from afar, they climb up the tree trunk each spring from the understory, or they overwinter in the canopy. Some manipulative experiments shows some winter-active birds feed on spiders in trees, suggesting some certainly might overwinter. However, I do wonder if this is commonplace in the systems I know around Montreal. This could be a great project, and would involve perhaps tagging spiders, using population genetics, or doing some good old fashion natural history observations.

What is the relatedness of different populations of synanthropic spider species such as Salticus scenicus (the “zebra jumper“)? Many spiders are “urban” spiders, and occur frequently in association with humans. When did they arrive to these cities? Does the age (and relatedness) of each city’s population of zebra jumpers relate to the age of a city? (Eg, compare a newish city like Calgary to an older city like New York…?). When looking at population genetics, do individuals move around a lot within a city (I suspect not), or between cities (I have no idea…). This would be a neat project, in part because of the attractiveness of the spider and its close association with humans, but also because it would be feasible! I think the methods could be quite straightforward, and would address a really interesting aspect of invasive species ecology.

A cute little zebra jumper! Photo by Alex Wild.

When ballooning, how frequently do spiders take off again after they land? Spiders disperse all the time by releasing strands of silk and “sailing away”, and they certainly aren’t restricted to one flight. There has been fabulous research done about their dispersal potential and habitat suitability at a landscape scale, but I am very curious about how often they land in a location only to depart again soon after. Why would they do this? Perhaps they don’t like their landing spot, perhaps there is a competitor or predator nearby, or perhaps they just feel like it. What clues do they use to leave a spot after they land in a spot? I really have no idea how to answer this kind of question….

Why do Pseudoscorpions tend to exhibit such clumped distributions? These tiny creatures are truly fascinating, and the basic biology and distribution of most species remains unknown. I have spent a lot of time searching for and collecting Pseudoscorpions, and I have found that their local populations are incredibly “clumped”. In general terms this means you can search for a long, long time and never find any individuals and then suddenly happen upon dozens. This alone is not unusual for many animals, but I have found Pseudoscorpions to be more patchy in their distribution compared to other arthropod taxa I have spent time searching for. Why is this? Maybe I am just really unlucky or hopeless when it comes to collecting these arachnids? Perhaps their low dispersal abilities keeps them from expanding their local range (they can’t fly or walk very quickly)?  However, many are phoretic and catch rides on other animals that can disperse effectively. Maybe Pseudoscorpions have very specific niches, and perhaps those niches are relatively rare? I just don’t know.

Ok, that’s it for now…

I do hope someone out there tackles some of the unanswered questions, or corrects me if I’ve missed some key literature on these topics. Please share, comment and provide input! I also urge others to post their unanswered research questions – theses ideas need to be written down and discussed. I think we will all benefit.

———

* There will surely be a Part 2, and I think this blog is a good place to throw ideas out there. It can be a type of “research notebook”, which can and should include unanswered (or unanswerable) research questions.

© C.M. Buddle

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3 thoughts on “Unanswered (Arachnological) research questions

  1. Great post–and your questions #1 and #2 combine to make me think of yet another. What about that 1975 study (Duffey, Green) that claimed to show medically significant bites from teeny linyphiid spiders? Was it ever backed up or reproduced? (I can’t seem to find a copy.) This comes to mind amid the recent news stories from Australia about ballooning linyphiids falling like snow. You can work your tail off reassuring people that ballooning is not only natural and common but that a 3mm spider isn’t going to hurt you, and then somebody finds the second- or third-hand reference to the 1975 study suggesting that they can. Thus there are various sites that list money spiders as among the “venomous spiders of Britain.” Sigh.

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