The effect of insecticides on jumping spider personalities

This post was written by C. Buddle and R. Royaute (a PhD student in the Arthropod Ecology lab).

We are pleased to announce a recent publication from our lab, titled Interpopulation variations in behavioral syndromes of a jumping spider from insecticide-treated and insecticide-free Orchards.  As is traditional in the lab, here’s a plain language summary of the work:

Agriculture has strongly intensified in the last 60 years, causing major concerns the sustainability of biodiversity. Agricultural practices can reduce habitats available for wildlife and also release toxins in the environment through the use of pesticides. Not all organisms living in agricultural fields are harmful, and many predators, including spiders, can help to reduce pest density. We have a relatively good knowledge that the diversity of spider species in agriculture, especially under our temperate latitudes, can help reduce pest damage. However, many of the factors that influence spider predation on pests depend on the outcome of behavioural interactions and we don’t know much about that topic. Spiders are often cannibalistic and aggressive with one another and these types of behaviours may limit their efficiency for pest control. We also need to understand if these aggressive tendencies vary depending on the type of agricultural field considered, a pesticide treated field may favour very different behaviours than one that is managed organically. Another important point is that populations are composed by a multitude of individuals, each with its own behavioural tendencies. Some individuals take more risks when confronted with predators (i.e. they are more bold), others are more active and explore larger areas or consume more prey. These tendencies – often referred to as personality traits – may also be correlated with one another.

In the context of agriculture, this may mean that certain individual spiders may contribute more to biocontrol because they consume more prey, or that certain individuals are more at risk of being in contact with pesticides because they are more active. To understand, how agricultural practices, and particularly insecticidal applications, affects personality and behavioural syndromes in spiders, we focused on the jumping spider Eris militaris, an abundant and charming jumping spider occurring in apple orchards in Quebec. Here’s a lovely photo from Crystal Ernst to illustrate how attractive they are: (thanks, Crystal, for permission to post the photo here!)

Screen Shot 2013-11-26 at 3.34.45 PM

We collected spiders from pesticide-treated and pesticide-free orchards, brought them back to the laboratory, and did a number of behavioural tests on the individuals from the two populations. Compared to the insecticide-free populations, we document that individuals from orchards that did receive insecticides experienced a shift in their behaviours syndromes. The overall shape of this syndrome is multidimensional, but it suffices to say that the correlations among different behaviours (the ‘syndromes’, otherwise known as the ‘personality’) differed depending on where the population came from.

A 'mirror test' - used to study behaviour in E. militaris (photo by R. Royaute)

A ‘mirror test’ – used to study behaviour in E. militaris (photo by R. Royaute)

In sum, the personality shifts that we documented for E. militaris are potentially quite important since the relationships between different behaviours may affect a spider’s ability to be an effective generalist predator in apple orchards. We need to consider how management  (including use of insecticides) may affect specific behaviours, and more importantly, the relationships between the different behaviours.

Reference

Royaute, R., C.M. Buddle & C. Vincent. 2013.  Interpopulation Variations in Behavioral Syndromes of a Jumping Spider from Insecticide-Treated and Insecticide-Free Orchards. Ethology. doi: 10.1111/eth.12185

Arthropod Ecology Mission Statement

Last week, during our laboratory meeting, we worked to develop a laboratory mission statement. My real inspiration for this came from my friend and colleague Elena Bennett – she also got me connected to Jessica Hellmann’s excellent post on the topic.  A mission statement is really just a way to clearly define who we are, what we do, and why we do the sorts of things that we do. From a research laboratory’s point of view, the goal of the exercise is (in part) to help all members of the laboratory feel part of something bigger. Something that has broad relevance to a community that extends far beyond the walls of our institution, and far beyond the boundaries of our own specific research projects.

As Jessica states clearly in her post, a Mission Statement  “…is a description of the purpose for your organization, primarily as it now is and/or will be within the next few years. A good mission statement should accurately explain why your organization exists and what it hopes to achieve in the near future. It articulates the organization’s essential nature, its values, and its work. The statement should resonate with the people working in and for the organization, as well as with the different constituencies that the organization hopes to affect. It must express the organization’s purpose in a way that inspires commitment, innovation, and courage.”.  A mission statement should be short, easily remembered, jargon-free, proactive, and readable to people outside of our organization.

Here’s what we did to come up with our (draft) statement:

1) We each wrote down a few words or a short sentence on an index card. We tried to write things that we felt described what the laboratory does in a broader sense (i.e. beyond our own specific interests). Here’s an example:

Screen Shot 2013-10-09 at 10.04.24 AM

2) We mixed up these cards and each person took someone else’s card. We then went around the table and read what was on the cards. This allowed us a terrific jumping off point for the discussion and generated the necessary words and ideas.

3) The ‘scribe’ (in this case, it was me) wrote down each descriptive word (in our case, things like ‘arthropods‘, ‘human disturbance‘, ‘biodiversity‘ came up a lot), and as a group, we wrote down some verbs to help us think about the ‘action’ that we take with the things we do. Here, verbs like ‘explore‘, ‘quantify‘, ‘share’ came up a lot.

4) We wrote the mission statement – in two parts. (a) We tried to provide a few sentence of context, and to ground our laboratory in the ‘why‘ and the ‘what‘; (b) We wrote a few sentence of ‘how‘ we do our research.

5) Edit, edit, edit. This was done during the lab meeting, but also over email

Here’s the end result:

Mission Statement:

Arthropods (insects, spiders and their relatives) comprise most of the known biodiversity on the planet. Human activities are rapidly changing our environment, from climate change to landscape fragmentation and urbanization, with unknown consequences for local and global biodiversity. Arthropods have profound effects on ecosystem function, human health, goods and services, and culture. Our well-being is connected to this “smaller majority”, yet we know little about where they live, what they do, and how their diversity is changing. In our laboratory we: 1) Quantify patterns of terrestrial arthropod biodiversity across a suite of ecosystems, over a range of spatial and temporal scales; 2) Explore how arthropods respond to and are affected by human-induced environmental changes; 3) Investigate the interaction between arthropods and ecological processes; 4) Share our knowledge, ideas, and passion about arthropods.

How did we do? We would love your feedback on this.

Here are a few thoughts and reflections:

  • This was a very worthwhile process – it was an amazing discussion and gave as opportunity to really delve into areas that were well beyond our individual research interests.
  • I have always believed that ‘patterns in terrestrial arthropod biodiversity’ was really what I spend my research time thinking about; it’s good that the collaborative process of developing a mission statement ended up reflecting that!
  • Any specific habitat (e.g., canopy systems, the Arctic), or even any type of arthropod (e.g., beetles, spiders) never remained in our final mission statement. This is terrific, and shows well that the laboratory has diverse interests, but more importantly, that we encourage research in different places and with different model taxa.
  • Yes, jargon remains. This is difficult. We agreed, as a laboratory, that our mission statement would be aimed at a ‘scientifically literate’ audience.
  • I’m an ecologists and we do ecology, yet that word did not end up in the final product. Curious.
  • We ALL agreed about the importance of ‘sharing’ and engagement with a broader audience -many of us do various kinds of outreach, from blogs and tweets to volunteering to talk about insects in local elementary schools. I was extremely pleased and proud that our laboratory sees this is a core activity.

This process if far from over: the next step is a “Vision Statement“. As Jessica points out, a Mission statement is more about what we “do” and why, whereas a Vision Statement “...looks at least five years into the future and defines a future state. It is an articulation of a world that the organization and people are working toward, not what is expected to happen now“. Ok, that’s a task for a future lab meeting!

(BIG thanks to my amazing laboratory for helping develop a mission statement)

It’s a wrap! How about a thesis on Arctic spiders? How about two of them…?

This week I am thrilled to report that two of my MSc students have successfully completed their degrees! Both the projects are part of the collaborative Northern Biodiversity Program – a project aimed to quantify and understand ecological change with Arthropods from Canada’s north.

A BIG congratulations to Sarah Loboda and Katie Sim  - they are both tremendously talented students, excellent Arachnologists, and wonderful people to know.  Last night we had our annual Lab BBQ – and at that event, I was pleased to give Sarah and Katie a small token of appreciation.  Here’s a photo showing them both with their wolf spider photographs (photos by the incredible Thomas Shahan):

Katie Sim (l) and Sarah Loboda (r) - successful MSc students!

Katie Sim (left) and Sarah Loboda (right) – successful (& happy) MSc students!

Sarah Loboda’s thesis is titled Multi-scale patterns of ground-dwelling spider (Araneae) diversity in northern Canada. Her research focused on broad diversity patterns of ground-dwelling spiders collected from our 12 study sites, spread across Canada’s north. Our project spanned 30 degrees of latitude and 80 degrees of longitude –> yes that is a lot of land area! Sarah identified over 300 spider species from 14 families, and over 23,000 individuals.  Publications are forthcoming so I won’t give details here, except to say that we can learn a lot about diversity patterns over broad spatial scales using a study taxon such as spiders.

Here's where the Northern Biodiversity Program took our field teams!

Here’s where the Northern Biodiversity Program took our field teams.

Katie’s work (co-supervised by Prof. Terry Wheeler) had a different slant, but was still on Arctic spiders. Her thesis is titled:  Genetic analysis of Pardosa wolf spiders (Araneae: Lycosidae) across the northern Nearctic. The first part of Katie’s thesis was about understanding the phylogeographic history of the Arctic spider Pardosa glacialis, with particular attention to post-glacial dispersal patterns, as inferred by population genetics. The second part of her thesis was focused on whether or not there is enough evidence to suggest two northern Pardosa species should remain as separate species, or be merged into one – based on both molecular and morphological characters.  Let’s just say that Katie had to be a ‘field genius‘, ‘lab genius‘ and ‘spider genitalia genius‘.  Here’s an example of what she looked at, a lot:

The epigynum of a wolf spider species, (part of) the topic of Katie's research.

The epigynum of a wolf spider species, (part of) the topic of Katie’s research.

In sum, I am thrilled to see Sarah and Katie finish up their work, although their success also comes with a touch of sadness, as I will miss their daily presence in the laboratory.  Stay tuned… we shall soon report all the details from their research.

Seasonality of Arctic Beetles

I’m excited to report on paper written by Crystal Ernst, PhD student in my lab, and well known as the “Bug Geek“. This paper is a product of the Northern Biodiversity Program (yes, it sure is great that the papers from this project are starting to appear!), and will be one of Crystal’s PhD thesis chapters. The paper is titled Seasonal patterns in the structure of epigeic beetle (Coleoptera) assemblages in two subarctic habitats in Nunavut, Canada

A very nice Arctic beetle! (photo by C. Ernst, reproduced here with permission)

A very nice Arctic beetle! (photo by C. Ernst, reproduced here with permission)

Here’s a plain-language summary of the work:

Although we often think of Arctic systems as cold and lifeless, Canada’s tundra habitats are home to a high diversity of arthropods (insects, spiders and their relatives). Beetles are important insects on the tundra – filling ecological roles as predators (feeding on other insects), herbivores (feeding on plants), mycophages (feeding on fungi), and necrophages (feeding on dead or decaying animals). In this research, we wanted to find out what happens to ground-dwelling Arctic beetles as a function of seasonality. We were curious about whether different species occurred at different times during the short Arctic summer, and whether the functions of the beetles changes over the summer. This is an important area of study because beetles perform important ecological functions, and knowing how these functions change over time may have broader implications for northern ecosystems. This is especially relevant in the Arctic since these systems have a short ‘active season’, and climate change is disproportionally affecting northern latitudes. If climate change alters an already short summer, what might happen to the beetles?

This research was done as part of the Northern Biodiversity Program (NBP) – a broad, integrative project about the diversity of insects and spiders across northern Canada. The NBP involved collecting samples at 12 sites in the Arctic, but at one of these sites (Kugluktuk, in Nunavut) we had an opportunity to do a more detailed collection over the entire summer of 2010. This involved setting out traps for the entire active season, from June through to August. These traps were plastic containers sunk into the ground – beetles that wander along the tundra fall unawares into these traps, which contain preservatives, and are trapped until a researcher collects the samples. Traps were placed in wet and (relatively) dry habitats so that we could compare the two habitats. After the collections were returned to our laboratory, the beetles were identified to species, counted, and the biomass of the beetles was estimated – biomass lets us determine what happens to the ‘amount of beetles’ on the tundra in addition to figuring out ‘how many’ (abundance) and ‘what kind’ (species) were in the traps. The beetles were also classified into their key ecological roles. The data were then compared as a function of when traps were serviced to let us assess what happens to beetles as a function of seasonality.

We collected over 2500 beetles, representing 50 different species – remarkably, 17 of these species represented new Territorial records. This means that 17 of the species that were identified had never before been recorded in all of Nunavut! Although many ecological functions were represented by the beetles we collected, most were predators. We documented that wet habitats had different kinds of beetle species than the drier tundra habitats, even though the actual number of species between the habitats did not differ. We also uncovered a seasonal affect on the functions of beetles in the system – as the season progressed, the beetles tended to be represented more by predators compared to earlier in the season, which was dominated by beetles representing a diversity of functions. The mean daily temperature also related to the seasonal change that was observed in the beetles.

PhD student Crystal Ernst, happily working on the Arctic tundra.

PhD student Crystal Ernst, happily working on the Arctic tundra.

This work is one of the first to carefully quantify how beetles change during short Arctic summers. We found a diverse assemblage of beetles, filling a range of ecological roles. These ecological roles, however, do not stay the same all summer long, and the shifts in the beetles were related to mean daily temperature. Given that Arctic systems will be significantly affected by climate change, this is worrisome – if temperatures increase, or become more variable, this may affect ecosystem functions that are mediated by beetles. This is more evidence supporting the need to track climate change in the Arctic, and play close attention to the small animals of the tundra.

Reference:

Ernst, C., & Buddle, C. (2013). Seasonal patterns in the structure of epigeic beetle (Coleoptera) assemblages in two subarctic habitats in Nunavut, Canada The Canadian Entomologist, 145 (02), 171-183 DOI: 10.4039/tce.2012.111

WANTED: graduate students

Interested in arthropod ecology?

Interested in graduate school?

I’m seeking at least two graduate students.  One, at the MSc level, on a project related to pollinator diversity within an agroecology context.  This is a Quebec-based project, and bilingualism would be required. The second, at the PhD level, will be about Arctic arthropod biodiversity with a particular focus on temporal changes in community structure. The Arctic project will involve a combination of field and laboratory work, and will in part deal with historical specimens. Both projects will require a student with interests in both taxonomy and ecology.  In other words, significant time at a microscope as well as time doing quantitative ecology.  Start dates are negotiable, but there is potential for field work to commence in May/June 2013.  Required skills include excellent communication skills, ability to work in a large, dynamic laboratory, passion for arthropod ecology, and abilities/interest in quantitative ecology.  Experience in Entomology and/or Arachnology would be an asset.

Please do your homework:  read my blog, and do research about my research; try to assess if you think you’ll be a good fit within my laboratory group.

Interested candidates should e-mail me with a brief (<200 words) statement of interest, a brief (<200 words) statement that outlines relevant experience and skills, and a brief sentence or two about your expectations in the context of graduate school at McGill University.  Please submit these to me before the end of January 2013.

Taxonomic sufficiency in biodiversity research: Is it always necessary to identify species?

It’s been a successful few weeks in the lab!  Two weeks ago I promoted an exciting paper about spider silk and herbivory and just after that paper come out, another publication from our lab was published, titled: “Does species-level resolution matter? Taxonomic sufficiency in terrestrial arthropod biodiversity studies“.  This paper evolved out of a past graduate-level class in Forest Entomology at McGill, and was re-worked and re-written by post-doc Laura Timms, former Phd student Joseph Bowden, and my colleague Keith Summerville.

Let me provide a plain language summary of this work and I will also touch upon some of the controversy that has arisen because of this paper:

Biodiversity science is about the discovery and description of all the different kinds (species) of organisms living on our planet.  It is a vitally important area of research because different species play important roles in our ecosystems, and as a consequence, are important to us.  The different number of species in an area can also inform us about how we might be harming or helping ecosystems.  This is an active area of study in the context of forestry, since some forest practices (for example, cutting all the trees down in an area) can cause changes in the number of species (and whether they are rare or common) and these changes can inform us about whether our forestry practices are harming our ecosystems.  All of this kind of work, however, depends on the ability of scientists to collect, sort, and identify different kinds of species.  Since most described species on the planet are Arthropods (e.g., spiders, insects, and their relatives), these animals are often used as a way to indicate how biodiversity might be affected by environmental change.  However, there is a problem: it takes a very long time to identify different arthropods, and it is costly and difficult – requiring highly specialized training, by people known as taxonomists.  In our research project, we asked whether not you always need to know the exact differences between insects and spiders  in order to tell if a disturbance is affecting biodiversity.  We did this by looking at a series of data-sets about beetles (Coleoptera), moths & butterflies (Lepidoptera), and spiders (Araneae). These data-sets were from past research projects about how forest disturbance affects biodiversity.

Here is how we did the work: Different kinds of organisms are classified using a two-part name:  the genus and the species.  There can be many different species within one genus.  You can then classify different genera (the plural of genus) into grouping called Families.  For example, all wolf spiders are in the Family Lycosidae.  A common genus within this family is Pardosa – there are dozens of species of Pardosa in Canada; Pardosa mackenziana, Pardosa moesta, Pardosa hyperborea, etc.  We first took our big data-sets and using the lowest level of naming (the species) we asked whether forest disturbance affected biodiversity.  We then grouped all our species into their respective genera -this meant that the data-sets got smaller (i.e., there are necessarily fewer genera than species).  We did the same analysis to see if we could still get a signal about the effects of disturbance on biodiversity, but now with the ‘reduced’ data.  We did this again at the family level.  We did this because we wanted to know if you could take a short-cut. Stated another way, if you don’t have the time or ability to figure out all the species in your research project, can you still see if there is an effect of forestry on biodiversity?

A wolf spider (Lycosidae)

A wolf spider – do you need to know its name?

Our results showed that in most cases, you do not need to know the species identity to see the effects of forestry practices on the biodiversity of spiders, beetles and moths & butterflies – you do not get as clear answers when things were grouped into Families, but the datasets with species grouped into genera were almost as good as when you group things into species.  This was surprising, because an assumption in biodiversity science is that species-level identifications are necessary and should be the ‘gold standard’ for this kind of research.  We showed that in many cases, you can get your answer by identifying arthropods to the generic level:  this can save you a lot of time (and money).   Some researchers (including taxonomists) may not be thrilled with this result as it might suggest that species are not important, and specialized taxonomic knowledge is not essential to complete biodiversity research.  This is certainly not the case, which leads me to the caveats:

1) Our results do not mean species are not important!  Instead, we are saying that if there are logistical and financial constraints, you might be able to answer your research question without having to identify all the species.   If you have a project about large-scale disturbance and are looking to see whether there are any broad affects on biodiversity, our approach might work.   However, you might miss some subtle effects, so this approach must be taken with caution.  Although our suggestion is a short-cut, it would still be important to save all the samples, and at a later time (as money and expertise permits) the species could be determined.

2) Our study is specifically geared towards research about insects and spiders in relation to large-scale forestry disturbances.  We are not saying that this will work in all situations and with all different kinds of organisms! The context is important.  Related to this, if an overarching research question is about species in an ecosystem, species-level identifications are essential.  Everything depends on the research question and the research context.

3) This general approach that we have discussed is highly dependent on what kind of organisms you are studying.  If you are working with a group of organisms that do not have too many different species within a genus, our approach may work.  If, however, there are many species within a single genus, our suggestion will not work as well.  Therefore, a researcher should look at the general relationship between the number of species per genus for their study organisms and use this ratio as a guide when thinking about taking the short-cut that we discussed in the research.

In sum, we are quite excited about this research – we think it will provide more opportunities for biodiversity projects to get done, and will help answer certain research questions when there are substantial constraints on time and money.  This is one way to be pragmatic about biodiversity research.

Please share your thoughts!

Reference:

Timms, L., Bowden, J., Summerville, K., & Buddle, C. (2012). Does species-level resolution matter? Taxonomic sufficiency in terrestrial arthropod biodiversity studies Insect Conservation and Diversity DOI: 10.1111/icad.12004

Plain-language summary of research results: Mites, rotten wood, and forests

Last week I wrote a post that outlined a proposal to require plain-language summaries of all research papers. I decided that I would start to do this with my own papers to see how difficult it might be, and also to see if this could help to make the research more accessible to a broad audience.

So… here it goes. This is a summary of paper written with my former MSc student Andrea Dechene, about mites, forests and fallen logs:

         Mites are small animals, closely related to ticks and spiders. They are so small that it is very difficult to see them without the help of a magnifying glass or microscope. There are many kinds of mites, and they are found almost everywhere, including forests. Mites are important in forests because they can affect how leaves and rotten wood decompose on the forest floor. 

          In this research, we studied whether certain kinds of mites were associated with logs that were decomposing on the forest floor, and we did this work in north-western Quebec. We collected mites living in the wood, on the ground near the wood, and on the forest floor about 1 m away from logs. Mites were collected by taking a handful of soil, leaves or rotten wood, putting this in a zip-lock bag, and then the samples were taken to a laboratory. In the lab, these handfuls of soil, leaves and wood were placed on a bench below a light. Mites do not like bright lights and they try to get away by moving away from the light – in this case, they move downward where they think it is safe. The samples are on a screen, however, and the mites fall through the screen and into a jar that contains a liquid that will kill them. These jars are taken to a different lab where the mites are inspected with the help of a microscope. With the help of books and other resources, we could figure out all the different kinds of mites and sort them into their different varieties.  Some kinds had names while other ones did not 

         We discovered 80 different kinds of mites and over 15,000 mites, in total, fell into the jars. That means a lot of mites live in forests! We also discovered that different kinds of mites live in the rotten wood compared to the forest floor and compared to the leaves. We found that the most different kinds of mites actually lived in the leaves that were over top of very, very rotten wood. This is an exciting result because nobody figured this out before, and it means that long after wood decomposes, there are still animals that ‘remember’ the wood was there and are using it as a suitable place to live. Lots of scientists have worked on rotten wood and it is well known that wood is very important for many animals and plants in a forest. Our work is different because we looked at some of the tiny animals in forests and they are also telling us that rotten wood is a good place to live. Next time you see a fallen tree, remember that many kinds of mites depend on that tree and you should leave it where it is.

Mites live here.

Phew.

By the way, here is the actual Abstract from that paper:

The removal of timber during harvesting substantially reduces important invertebrate habitat, most noticeably microhabitats associated with fallen trees. Oribatid mite diversity in downed woody material (DWM) using species-level data has not been well studied. We investigated the influence of decaying logs on the spatial distribution of oribatid mites on the forest floor at the sylviculture et aménagement forestiers écosystémique (SAFE) research station in the Abitibi region in NW Québec. In June 2006, six aspen logs were selected for study, and samples were taken at three distances for each log: directly on top of the log (ON), directly beside the log (ADJ) and at least one metre away from the log and any other fallen wood (AWAY). Samples ON logs consisted of a litter layer sample, an upper wood sample and an inner wood sample. Samples at the ADJ and AWAY distances consisted of litter samples and soil cores. The highest species richness was collected ON logs, and logs harboured a distinct oribatid species composition compared to nearby forest floor. There were species-specific changes in abundance with increasing distance away from DWM, which indicates an influence of DWM in structuring oribatid assemblages on the forest floor. Additionally, each layer (litter, wood and soil) exhibited a unique species composition and hosted a different diversity of oribatid mites. This study further highlights the importance of DWM to forest biodiversity by creating habitat for unique assemblages of oribatid mites.

The Extractor – getting mites from the samples

Thoughts? –I kind of like the plain-language summary.

The plain language summary was not easy to write and it took a lot of words to explain certain things. Despite the challenge, I’m convinced it was a worthwhile use of time.  Please consider doing this with your own papers!  

Reference:

Dechene, A. and C. M. Buddle. 2010. Decomposing logs increase oribatid mite assemblage diversity in mixedwood boreal forest. Biodiv. Cons. 19: 237-256. http://www.springerlink.com/content/r3681l0185620311/

Spider cakes!

My graduate students are a very talented bunch – they are intelligent, creative, and have a good sense of humour.  Some of our lab group celebrated birthdays recently, and in honour of this, we had two cakes earlier this week.  The first, made by MSc student Sarah Loboda, is the VERY BEST SPIDER CAKE I have ever seen (or eaten!).  Check this out:

Spider Cake!

Of course, let’s discuss how anatomically correct that cake is!  Two body parts, pedicel, eight legs (coming from the cephalothorax, of course), and a bunch of eyes.

Spider cake! (eyes0

As you may know, most spiders in Canada have eight eyes, but since some do have six, I find it quite acceptable that this spider has six eyes.  Furthermore, not all spider eyes are identical so it is appropriate to have two kinds represented on the cake.  Well done, Sarah.

And in case that STUNNING MASTERPIECE isn’t enough, another student (Dorothy Maguire)  made a cake that is a very good approximation for the female epigynum of wolf spiders in the genus Pardosa.

Pardosa epigynum

And not just any Pardosa:  this is diagnostically similar to one of the species that graduate student Katie Sim is working on!  Incredible!

….want some proof – look at this image, taken from Dondale & Redner’s text on the Lycosidae of Canada.  Enough said.

Pardosa concinna epigynum

Arthropods in the tree-tops: Canopy ecology in Quebec (Part 3)

This is the final post in a three part series about studying canopy arthropods in Quebec.  Part 1 was about canopy access and Part 2 was about patterns of diversity.  This post is about ecological interactions in the canopy. 

I had the pleasure of supervising a M.Sc. student, Kathleen Aikens, who was keen to work on a canopy project that looked deeper into some of the ecological interactions occurring in our deciduous forest canopies.  This was possible since we had, by this time, acquired a lot of base-line data on arthropods in many strata of the forest.  Kathleen’s work included using exclosure cages to see whether or not bird predation might affect arthropods in the Canopy differently than in the understorey.   This was exciting work, as it took our laboratory in a new direction, and lets us start to unravel some of the complexities of the food-webs in the tree-tops.  Her main result was that birds did have a strong top-down effect on arthropods, and that effect did differ as a function of height.  Using some bait trials, we also found that predation by arthropods on arthropods was also stratified.   This research suggests that arthropods living in trees in our region of the world are always under significant predation pressure, from both vertebrate and invertebrate predators.

A cage experiment, to assess the effect of predators on insects living in the forest canopy.

More recently, my laboratory has started to collaborate closely with another group at McGill studying “ecosystem services” – this is work done with Elena Bennett, another colleague at McGill University.  The research framework with this project is about how different ecosystem services are affected by the fragmented landscape that occurs in a large region just south of Montreal.  Elena and I co-supervise a PhD student Dorothy Maguire, who is looking at the ecosystem function of insect herbivory, and studying how herbivory varies as a function of forest size and degree of isolation (i.e., from a large contiguous forest), and she is studying herbivory in the understorey as well as the canopy.  Herbivory is closely linked to ecosystem services because of its effect on nutrient cycling, forest aesthetics, and more.  Although this project is currently underway, Dorothy is uncovering some interesting results, already.  For example, she is finding that levels of insect herbivory differ between the understorey and the canopy, and that forest fragmentation is affecting insect herbivory.

Summary

I have provided some highlights of some of the work that our laboratory has done in Quebec’s deciduous forests (and my apologies to the students who I didn’t mention!).  Although we have come a long way, and uncovered some interesting research results, I still feel that the work is just beginning.  For example, the bulk of our work has been on only two tree species (Sugar Maple and American Beech), and we have only studied a fraction of the arthropods that exist in the canopies of our forests.  I would like to expand the research to include other plant-feeding guilds, bees and wasps.  I’m also always curious about the piles of dead and decaying leaves that we find nestled between the crotches of high branches – these micro-habitats surely contain suspended soil (e.g., see Lindo & Winchester 2007), and within those “islands” there should be a host of arthropods.   Not surprisingly, the forest canopies in southern Quebec are home to a marvelous diversity of arthropods.  It’s a scientist’s model system, and a delightful system in which to work and play.

Me (Chris Buddle) above the canopy at Mont St Hilaire!

Arthropods in the tree-tops: Canopy ecology in Quebec (Part 2)

Part 1 of this series highlighted how our laboratory accesses the forest canopy.  This post is about our projects related to understanding patterns of Arthropod diversity in Quebec’s forest canopies.

I will first highlight some work done by my former PhD student Dr. Maxim Larrivée.   Max started in my lab at the exact time that I received the grant for the mobile lift platform, and he become an expert at this machine, and he proved to be an immensely talented student.  His project was focused on understanding the spatial patterns of spider diversity in three deciduous forest sites located within an hour drive of the Island of Montreal.  In the first part of his dissertation, Max collected almost 14,000 spiders representing 82 species (Larrivée  & Buddle 2009).  The spider fauna of the canopy was markedly different from the fauna from the understorey, and it is likely that different mechanisms structure the assemblages in the two habitats.

Overall fewer spiders and fewer spider species were found in the canopy compared to the understorey, but at a species-specific level, there were some spiders that seemed to have a preference for living in tree-tops.  For example, the lovely jumping spider (Salticidae) Hentzia mitrata was significantly more common in the canopy.   We were also most excited to document the species Mastophora hutchinsoni (Araneidae) in the canopy – this is the famous “bolas spider” and we believe our canopy record may be the most northern record for the species.  The Bolas spider hunts by swinging a strand of silk at its prey, and this strand has a “bolas” of sticky capture thread at the end.  This species is truly fascinating, and in our system, it is a species that likes the canopy.

Max demonstrating the methods of using a beat-sheet to collect spiders in the forest canopy. Here, he is about 25 m above the forest floor.

The follow-up work to this baseline study was focused on understanding dispersal potential of spiders in the canopy as compared to the dispersal potential of understorey species.  Most spiders in our system are small, so we predicated that their main mode of dispersal was via ballooning (i.e., releasing a small strand of silk and letting the wind carry the spider away).  We had also hypothesized that dispersal might be one of the mechanisms behind the aforementioned patterns community structure in the canopy compared to the understorey.  Max collected live spiders in the canopy and understorey and set them up in a wind-tunnel in the laboratory.  He then documented each species’ propensity to disperse by looking at the frequency by which they showed ‘tip-toe’ behaviour (a pre-ballooning condition).  In the paper resulting from this research, we reported that the spiders in our system do have high dispersal potential, but that this potential did not differ depending on whether the spider was collected in the canopy as compared to the understorey (Larrivee & Buddle 2011).   This was a fascinating area of study, and we are left with as many questions as we started with!   For example, if dispersal potential doesn’t differ between canopy and understorey species, what mechanism drives the differences in community structure between the two habitats?

Our laboratory has been studying beetles as well as spiders – although I am personally very interested in spiders, I do recognize the beauty of beetles, and their important ecological roles in virtually all ecosystems.  One of Max’s field assistants (Brianna Schroeder) was keen to complete a small project about beetles so she set Lindgren funnels in the canopy and in the understorey.  Over 170 species were collected, and once again, the fauna from the canopy was differentiated from that of the understorey (Schroeder et al. 2009).

Max up in the canopy crane!

Two other field assistants that worked with Max (Kristen Brochu and Katleen Robert) also worked on their own projects, and together with my colleague at McGill University (Prof. Terry Wheeler), we are close to finishing up a manuscript to describe more patterns of arthropod diversity as a function of vertical stratification in Quebec’s deciduous forests – this work includes beetles as well as flies (Diptera).  Although the responses are not the same for the different groups of insects, we are finding that both beetles and flies show vertical stratification in our study sites.

Stay tuned for Part 3, which will focus on ecological interactions occurring in the Canopy.