Yukon field work: Arachnids, landscapes, and the inspiring North

It’s a dream for an arthropod ecologist: a dramatic biome transition from boreal forest to subarctic tundra, a beringian landscape, and diverse and abundant insects and spiders. I have just returned from field work along the Yukon’s Dempster Highway, Canada’s only road to cross the Arctic circle. And again, I was not disappointed!

A stretch of the Dempster Highway

A stretch of the Dempster Highway

This year’s expedition was focused on three projects:

1) Tiny, wonderful arachnids:

On this trip, I continued to document the distribution of an arctic Pseudoscorpion, Wyochernes asiaticus. This is a beringian arachnid, known from the old world, and known in North America from almost exclusively unglaciated parts of the Yukon and Alaska. Like wooly mammoths and giant short-faced bears, these tiny arachnids roamed North America while the rest of the top half of the continent was buried under ice. But unlike the mammoths and giant short-faced bears, the Arctic Pseudoscorpion is not extinct! It’s a relict of the past, thriving today under rocks near beringian rivers and streams. I have been working on this species for many years (and a life history paper about this arachnid will appear in the Canadian Field-Naturalist sometime this month), and each time I visit the Yukon, I leave with more questions, and more specimens. This time, I collected some animals to hopefully work on their population genetics: I am curious about the relatedness among the populations from different watersheds along the Dempster Highway (by the way, I am seeking collaborators [phylogeographers!] for this work… If interested, let me know!)

The Arctic pseudoscorpion, Wyochernes asiaticus

The Arctic pseudoscorpion, Wyochernes asiaticus

2) Northern food webs:

I have left my PhD student Shaun Turney up in the Yukon (along with his field assistant) where he is working on characterizing the arthropod-based food webs along the latitudinal gradient of the Dempster Highway. Past research has given some hints that northern food webs may be atypical, but to fully test this we decided to characterize the entire fauna from 1 x 1 m patches of the tundra. This involved placing tents over the tundra, and Shaun collected critters within those tents, and even “vacuumed” the tundra within the square metre. Shaun started this work near the stunning Richardson mountains above the arctic circle, and over the month of July, will repeat the sampling at different locations along the Dempster Highway.

Shaun Turney, vacuuming the Tundra.

Shaun Turney, vacuuming the Tundra.

3) Thermal biology of wolf spiders

Colleagues from Western University joined me in the Yukon to start some projects related to the thermal biology of the extremely abundant Pardosa wolf spiders which inhabit the tundra. There are several species that occur along the Dempster Highway, and when the weather is good, it’s quite possible to collect hundreds of individuals over the span of several hours. Past work has suggested the density of these spiders is about 0.5 per square metre, and those past estimates certainly seemed accurate on this trip also! The spiders will be taken back to their lab, and I am eager to find out how northern Pardosa may be adapted to Yukon conditions.

Searching for wolf spiders on the Tundra

Searching for wolf spiders on the Tundra

All the sciency parts of our field work were exciting and gratifying, but there are other reasons why the Yukon is special*: it is a breathtakingly beautiful place. From stubby black spruce trees to tufts of tundra-dwelling cotton grass, every turn of the highway or footstep over a hummock is a treat. It’s not all easy (hordes of mosquitoes at some of the campgrounds, or being driven off the tundra by cold rains and strong winds), but it is all inspiring.

The lines between science and passion are blurred on the tundra, and that is a good thing. Searching for spiders is work that is fun; seeing a northern shrike or watching two lonely caribou dart up a river valley is fun that comes with the field work. I am immensely grateful for being able to hike under midnight sun, and be a northern researcher during the day. I am delighted to be able to discover some of hidden secrets of the Yukon.

The northern landscape, near the Yukon-Northwest Territory border.

The northern landscape, near the Yukon-Northwest Territory border.

For more photos of the recent trip, check out my Flickr page.

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* my colleague Terry Wheeler shares a passion for the Yukon – here is his post which outlines why he keeps returning to the region.

Spiderday (the ninth)

Here’s your ninth edition of SPIDERDAY! Some arachnid-related links from the past week.

Please note: I’m just heaving off to the Yukon for a couple of weeks of remote field work (it will involve arachnids!). Spiderday will likely return on 18 July.

Wow - this is a Thomisidae (crab spider) that's an ant-mimic. In Australia, of course. Photo by Alex Wild.

Wow – this is a Thomisidae (crab spider) that’s an ant-mimic. In Australia, of course. Photo by Alex Wild.

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  • Scorpions, anyone? How about GIANT ones. An amazing post with stunning images that you just won’t believe!
  • Some very handsome Opiliones (Harvestmen, or daddy-longlegs)
  • This is from a while ago, but worth another read. The fastest land animal (scaled to relative body size) is… a MITE!
  • Tips for tick safety. Worth a look.
  • Here’s a great technique that arachnophiles are sure to use!

Spiderday (the eighth)

Hip Hip Hooray! It’s Spiderday! I’ve snared some of the best arachnidy links from this past week. But first… a big hug for you:

A spider hug.

A spider hug.

A spider found for the first time in Canada: Myrmarachne formicaria (photo by V. Levesque-Beaudin, reproduced here with permission)

A jumping spider found for the first time in Canada: Myrmarachne formicaria (photo by V. Levesque-Beaudin, reproduced here with permission)

Spiderday (the seventh)

Welcome to spiderday. THE place to get all the stories about arachnids, from the past week. And boy oh boy it was a good week!

Let’s get started:

A spider from Singapore: it vibrates its web at high speed if it's threatened. Wow.

A spider from Singapore: it vibrates its web at high speed if it’s threatened. Wow. Photo by Chthoniid, reproduced here with permission.

A spider of sorts.

A spider of sorts.

A mitey good pun.

A mitey good pun.

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.

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* 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

Spiderday (the first)

I have decided to start a new, weekly feature* on my blog titled “SPIDERDAY!”. This will, fittingly, come on Saturday, and will be a bit of a round-up of stories about Arachnids from the previous week. I will include some images, links to neat Arachnid-themed blog posts and scientific papers, and bring other fun news about Arachnida. The pedants may be annoyed with “Spiderday” as a title to capture stories about all of the Arachnida (which includes mites, ticks, scorpions, harvestmen, etc.), but “Arachniday” doesn’t flow quite as nicely.

So, please enjoy, share, and let me know if you come across neat stories about Arachnids, and I will include them in next week’s Spiderday.

A long-jawed orb-web spider (Tetragnatha), by Sean McCann, reproduced here with permission.

A long-jawed orb-web spider (Tetragnatha), by Sean McCann, reproduced here with permission.

Here are some things I pulled from the “web” this past week:

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© C.M. Buddle (2015)

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*I’m not new to doing ‘regular features’ – I ran Expiscor for many months on this blog, and then did Segments on SciLogs for a while. However, I think an Arachnid-themed regular feature will have more staying power, and is a niche that needs filling, with eight-legged greatness.

Earthworms at the Morgan Arboretum

This is a post written by undergraduate student Jessica Turgeon – she’s finishing up a project about earthworms.

When I was a child, you could always find me either in a tree or in the dirt. I liked to follow the ants up into the trees and back down again, where I would switch over to digging for earthworms. I loved the feeling of soil between my hands and thinking to myself that these little worms were responsible for making the soil the way it is. I now know that the process is a bit more complex than this but overall, five year old me was almost right.

JessicaI spent my whole life loving nature, especially those living in it. By high school I became a strong advocate for environmental protection, even helping a teacher create a bylaw in my municipality to stop parents from idling in front of elementary schools. This experience truly opened my eyes to the will power and determination this generation has when it comes to changing old mentalities about the environment.

When choosing a university to go to, there was no doubt in my mind whether I should apply to Environmental Biology at the Macdonald campus of McGill or not. This program combines both of my passions: nature and its diversity and environmental management. I’ve since embarked on an amazing journey that has shaped me as a person.

Being around so many naturalists rekindled my love for earthworms, so much so that I decided that I wanted to conduct a research project about them. With the help of Chris Buddle (McGill) and NSERC USRA, I decided to take on a project detailing their biodiversity at the Morgan Arboretum, a nearby forest.

Earthworms can greatly affect Southern Quebec soils because all of the species found here are invasive1. Forests have evolved without the help of earthworms, meaning that earthworm burrowing action is somewhat of a new experience for the trees1. The worms break up and mix the soil when they crawl, leaving the soil readily susceptible to erosion2. While earthworms are prized by gardeners as natural tillers, this can have drastic effects on hardwood forests2.

It was important to me to find out where certain earthworms were in the Morgan Arboretum and why they were there. Soils vary in their composition and properties, meaning that some are more suitable for earthworms than others. The goal of my project was to analyze three different soil types (sandy, clay, loam) with regard to earthworm species. I did so by sampling in the three soils and by collecting and analysing the soil using basic soil analyses.

I found no earthworms in the sandy soil over the course of the sampling period, strongly suggesting that no earthworms inhabit sandy soils. Sandy soils are too rough and painful for earthworms to crawl through, therefore they are actively avoided. The clay and loam soils had much higher numbers of individuals, with 9 species each. After statistical testing, it was concluded that there is no significant difference between the two soils and it could be said that they are similar in biodiversity. In addition, a strong correlation between particle density (how dense the soil is) and earthworm abundance was found. As particle density increases, to a certain extent, so does abundance.

Earthworm Sampling

To conclude, my data suggests that the clay and loam soils in the Morgan Arboretum are similar in biodiversity, both supporting an equally diverse number of earthworm species. However, the sandy soil does not contain any earthworms, suggesting that this type of soil is incapable of supporting earthworm activities. This is interesting information for soil management, since, in terms of earthworm abundance and biodiversity, clay and loam soils are similar.

Earthworms are essential ecosystem engineers that change the soil to better suit their lifestyle and this is why they are often studied. Hopefully my story has encouraged readers to respect earthworms a bit more; after all, they do much more than be an excellent fish bait!

 

[1]        Cameron, E. K., Zabrodski, M. W., Karst, J., & Bayne, E. M. (2012). Non-native earthworm influences on ectomycorrhizal colonization and growth of white spruce. Ecoscience, 19(1), 29-37.

[2]        Jouquet, P., Dauber, J., Lagerlöf, J., Lavelle, P., & Lepage, M. (2006). Soil invertebrates as ecosystem engineers: intended and accidental effects on soil and feedback loops. Applied Soil Ecology,  32(2), 153-164.