Weird locomotion – ‘upside-down gliding’ by snails

This has nothing to do with my research but I find this next observation a really interesting natural history occurrence; Snails floating upside down on the water surface (Figs.1-2). I noticed this behaviour for the first time three years ago when I was doing fieldwork near Ottawa, I thought “cool” and “that’s weird” and “why do they do that?” at the same time but I had my thesis to focus on at the time so I didn’t put much more thought into it. I noticed it again this summer in Fredericton while on a walk with my dog and thought it is time to think about some more.

Fig. 1: upside-down gliding behaviour by a snail

Fig. 1: upside-down gliding behaviour by a snail

If you do a quick google search of “snail swimming upside down” you get hundreds of thousands of hits asking whether the snails in their tanks are dead, I suspect that a portion probably have died but the other portion may be doing this behaviour. So now I know that this upside down swimming also happens in both natural (field) and home/lab (experimental) settings. During this google search I also found a paper that looked at the mechanism of this behaviour they termed “Upside-down Gliding” (Aono et al 2008 – A project worked up by a group of high school students). They focused on the mechanism of the behaviour but not why. They were very thorough; in a lab setting, they measured the speed of locomotion, whether the snails secrete mucous while they’re upside-down gliding and whether the cilia on their foot is beating. Apparently, a snail can go between 0.8-1.6mm/s while upside-down gliding (depending on time of day and temperature), they secrete mucous and the cilia on their foot beats to move them forward. I found these finding very interesting but they did not answer my question of why the snails do this behaviour.

Fig. 2: Close-up of upside-down gliding snail.

Fig. 2: Close-up of upside-down gliding snail.

I can only speculate as to why: (1) maybe it depends on the oxygenation in the water, there’s not enough oxygen in the water so they glide at the surface; (2) maybe they’re feeding, gleaning particles off the surface of the water, (3) maybe it’s safer, fewer of their most dangerous predators at the surface, (4) maybe it has something to do with parasitism, (5) maybe they can move faster this way than if they were at the bottom, (6) maybe it’s a way of finding mates, (7) maybe they’re drunk (I found this last one on a google site and I very much doubt that’s happening).

I still don’t know the answer why snails glide upside-down… but it’s a lot of fun to watch them do it. Natural history observations in action! (I’ll try to post more of these kinds of natural history observations)

 

Reference

Aono, K., Fusada, A., Fusada, Y., Ishii, W., Kanaya, Y., Komuro, M., Matsui, K., Meguro, S., Miyamae, A., Miyamae, Y., Murata, A., Narita, S., Nozaka, H., Saito, W., Watanabe, A., Nashikata, K., Kanazawa, A., Fujito, Y., Yamagishi, M., Abe, T., Nagayama, M., Uchida, T., Gohara, K., Lukowiak, K. and Ito, E. 2008. Upside-down gliding of Lymnaea. Biological Bulletin 215: 272-279.

Leave a comment

Filed under Uncategorized

Times of Change part 2: studying different systems

As you know, I have been working on explaining why some damselfly species have more external or internal parasites than other damselfly species (Fig. 1). I was hoping for nice clear patterns, but sadly, as with most study systems of nature that was not meant to be. The story is complicated. It is a very interesting story that I will always find fascinating and hopefully try to resolve in the future, but I needed a change, a new challenge. So I’m moving into a new world, the one of associations between leafminers that feed on asteraceous plants. Even though a lot of research has been done documenting what leafminers feed on what plant, little has been done with this system in the evolutionary ecology context.

Fig. 1 1 A super infected Enallagma ebrium damselfly.

Fig. 1 1 A super infected Enallagma ebrium damselfly.

Leafminers are an interesting group because the term does not include one particular family of insects; leafminers can be either flies (agromyzids), micro moths, beetles, or even sawflies. As a group, or guild, they feed on the tissue within leaves but without damaging the upper or lower layers of the leaves (Fig. 2). Some pupate within the leaf, others drop onto the ground and pupate in the ground, it’s a species’ thing.

Fig. 2 A leaf mine on a Solidago gigantea leaf

Fig. 2 A leaf mine on a Solidago gigantea leaf

I have been at collecting leafminers for about a month now. It’s pretty different collecting from the last system I have collected, damselflies and water mites. There are similarities and differences. Here are a few that I noticed so far.

Similarities:

1- Walk around randomly a through a field looking for small things (Fig. 3).

It’d one of the best parts of fieldwork; just walking around fields inspecting every plant for what you are looking to collect. Especially in the type of collecting where you are looking for specific things; as in the case of damselflies and leafminers, you can’t just sweep or pick anything you like, you have to be selective. But that means wandering around looking like you dropped your keys and not caring what anybody thinks about it.

Fig. 3 Walking randomly in the field looking for the specimens you need

Fig. 3 Walking randomly in the field looking for the specimens you need

2- Challenges of species identification.

It is hard and it takes time to get to know the species you are looking for well enough to be able to find them on the fly. But with enough practice and time, you’ll be able to spot the right habitat for your species straight away and you’ll get a feeling that what you are looking for is there.

3- Overheating because you’re out in the open sun

When collecting in fields, it can get very hot in the middle of the summer. This applies to any collecting if you are not high in elevation or latitude.

4- Sitting in the grass looking at your study and other critters.

The most important part of any fieldwork is sitting down, relaxing and letting the habitat sink in. If there are any type of berries, have a snack! You can be having lunch and observing everything around you. I definitely recommend it for anybody considering themselves field biologists. If somebody considers his/herself a field biologist already knows this though.

Differences:

1- Collecting equipment needed for damselfly collecting – aerial sweep net, vials, notepad, pencil (Fig. 5). Equipment needed for leafminer collecting – vials, notepad, pencil.

Fig. 5 Essentials for damselfly collecting; a net, vials, notebook and something to write with.

Fig. 4 Essentials for damselfly collecting; a net, vials, notebook and something to write with.

Collecting many leafminers doesn’t require any type of specialized equipement other than your fingers. Collecting damselflies with your hands can be done, but if you want to sample many damselflies it would take a long time, I recommend an aerial sweep net.

2- Damselflies fly away, leafminers are stuck in their leaves so they’re not going anywhere.

As most know damselflies are flying insects and they do not want to be caught. They can quickly disappear into the grass or into the trees. It was always quite frustrating, when preparing the sweep net to catch it, it let’s go of it’s perch as is taken by the wind not to be found. I always thought anthropomorphizing “nicely played damselfly, nicely played”. Leafminers on the other hand, because they’re feeding in a leaf, can’t get away. So once you spot one, you can tear of the leaf and the larva will happily keep growing inside as if nothing ever happened. Although the only problem is once the have emerged, you can find empty mines with no leafminer.

3- Challenges of species identification

I know this is in similarities as well, but for damselflies, the challenge it to identify the damselfly to species, and with leafminers, it’s identifying the plant that key. Once the emerge from its pupa, you can identify the leafminer. Although you can make an educated guess about the species based on the mine shape.

5- Collecting damselflies ends at the field, then it’s processing the samples in the lab for parasite determination. You know what you’re getting when collecting damselflies. Since you’ve identified the damselfly while collecting, you know what you have.
Collecting leafminers continues in the lab (Fig. 5); when you’re rearing, you don’t know what is going to be reared from the mine – parasitoids or the actual fly! Which miners have emerged? from what plant? Is it the leafminer or the parasitoid? The anticipation and excitement of finding out what’s going to come out is immense.

Fig. 5 Rearing leafminers from Solidago leaves.

Fig. 5 Rearing leafminers from Solidago leaves back in the lab.

Enjoy the outdoors!

Leave a comment

Filed under Uncategorized

Times of change (Part 1): next steps in a career

As my last post mentioned, I have defended my thesis successfully and my PhD supervisor, Mark Forbes, has hooded me (Fig. 1) so I can officially be called a Doctor.

My supervisor, Mark Forbes, hooding me, making my PhD official.

My supervisor, Mark Forbes, hooding me, making my PhD official.

It’s a nice feeling, but at the same time it brings a time of uncertainty. During my thesis work, I was been safe at my desk in a lab or in the field for the last 4 years where I carved out my little niche. I felt safe after I got used to my system. I did my thing; looked at parasites of damselflies and figured out what’s what and why.

I guess it happens at every degree or every period of your life, there is uncertainty and not knowing what’s going to happen. [At the dog park in Ottawa I was talking with another dog owner who is about to retire, we had the same insecurities; what are we going to do with ourselves? Are we going to like it?…]. One thing that is clear it is necessary to be prepared; I tried very hard to have something lined up after I finished my doctoral thesis. I talked with potential post-doc supervisors and applied for funding. Luckily, I got funding. So now I’ve moved to a new place, (Fredericton, New Brunswick) a new lab (the Heard lab) and a new project (leafminers of Asteraeceae). It’s a strange feeling leaving behind the comfort of the known and moving into the unknown. But the welcome has been awesome. After 2 days in the lab I feel right at home. People are very nice, and even my dog, Maya, is making new buddies to wrestle with. There’s so much new to see and experience and learn. It’s going to be good!

Leave a comment

Filed under Uncategorized

a new paper, a new hypothesis

Recently my PhD supervisor, Mark Forbes, and I have published a paper “A hypothesis to explain host species differences in resistance to multi-host parasites” in Ideas in Ecology and Evolution outlining a new hypothesis in testing the evolution of resistance of host-parasite associations (Forbes and Mlynarek 2014, find it here). This hypothesis outlines the reasons why certain hosts can kill their parasites while their close evolutionary relatives can’t.

Through observations of dragonflies and damselflies, we noticed that sometimes two closely related species differ in whether they are able to resist their parasites. We note three cases in this paper where one of the host species cannot kill (resistant) the parasitic mite whereas the other is a lot more resistant:

1- Sympetrum obtrusum and Sympetrum internum infected by a mite, Arrenurus planus (Forbes et al 1999) where S. internum almost always kills the infecting mites.

Sympetrum obstrusum. The more widespread of the two Sympetrum dragonflies

Sympetrum obstrusum. The more widespread of the two Sympetrum dragonflies

 

2- Leucorrhinia frigida and Nannothemis bella infected by a mite, limnochares americana (Lajeunesse et al 2004) where N. bella kills more their mites.

Nanothemis bella

Nanothemis bella. The little dragonfly that can kill its parasites

 

3- Nehalennia gracilis and Nehalennia irene infected by a mite, Arrenurus sp (not yet described) (Mlynarek et al 2014) where N. gracilis always kills all the infecting mites

Nehalennia irene

Nehalennia irene. The very widespread damselfly that cannot kill its parasites

 

Each of the host species that kill their mites more readily are also the host species that are less common. By less common I mean that they cannot be found in a few locations.

The obvious question is ‘why would it be that the less common species is better at getting rid of their parasites than the more common one?’ Logically, it should be the other way around. The common species, because it comes into contact with more parasites species, should be better at generally recognizing what would hurt them rather than the uncommon species that has not had the same experience. But clearly in several cases of dragonfly hosts parasitized by water mites it is not the case. But the uncommonness of the species may be where their success lies.

This paper therefore puts forth a reason for the pattern that we see. I mentioned before that each of the species that kills their parasites is present in fewer locations. When a species is in fewer locations, it probably cannot disperse or travel to other locations. So it can only breed with the other individuals of that species present at that location and this leads to less genetic mixing between populations for this species. This may benefit that species because certain individuals are successful at killing their specific parasites and then those individuals pass those traits to their off-spring and resistance can evolve with time. Whereas the common species, that can easily mix individuals between locations, may swamp out those resistance traits because there is just so much of that species everywhere.

So this hypothesis proposes that it may be good to be rare! At least it may be good to be rare to a certain extent.

References

Forbes, M.R. and J.J. Mlynarek. 2014. A hypothesis to explain host species differences in resistance to multi-host parasites. Ideas in Ecology and Evolution 7: 17-24.

Forbes, M.R., Muma, K.E. and B.P. Smith. 1999. Parasitism of Sympterum dragonflies by Arrenurus planus mites: maintenance of resistance particular to one species. International Journal of Parasitology 29: 991-999.

Lajeunesse, M.J., Forbes, M.R. and B.P. Smith. 2004. Species and sex biases in ectoparasitism of dragonflies by mites. Oikos 106: 501-508.

Mlynarek, J.J., Knee, W. and M.R. Forbes. 2014. Explaining resistance in a multi-host parasite. Evolutionary Biology 41: 115-122.

Leave a comment

Filed under Uncategorized

Grad School Done!

I have successfully defended my PhD thesis “Explaining Interspecific Variation in Susceptibility and Resistance to Parasitism in Damselflies”! My program took me 4 years and 3 months to complete; it was worth every minute. My defense was difficult, I could have done so much better and I know it, but I did my best. Going into the defense I felt theoretically and practically ready, I was just too nervous. But even through my nerves, my examining committee saw that I knew my stuff. I’m glad they did.

Because I’m very fresh out of graduate school, so I thought I’d highlight a couple keys points that I noticed every one of my graduate student friends/colleagues have.

First, patience and perseverance! For the students thinking about graduate school, it is a slow process with lots of highs and quite a few lows. You have to be able to persevere! You will persevere if you like what you’re doing and if you are passionate about what you are studying.

Second, a hobby! This one may surprise you considering that graduate studies are so time consuming that they take up most of your time and are pretty much considered a lifestyle. But you need a hobby to take your mind away from your project at least for an hour a day. Mine is my dog (Maya), maybe I shouldn’t call her a hobby. But she makes me happy. Taking her on walks/hikes and playing/training her gives me the necessary breaks. So whatever you do, find something that pulls you away from your graduate projects. It should be something that doesn’t make you feel guilty that you are not working on your thesis.

Remember to have fun!

Leave a comment

Filed under Uncategorized

The last leg of thesis writing

Thesis writing is a long and hard process. When you think about it, you have been working (almost) non-stop on it for several years and the time has come to let it go and see how it develops in the real world. At the same time, it is difficult because, hopefully, some of your papers have been published so you have to revisit them and re-format them to the specifications of your university. It feels like you’re re-submitting a manuscript that has already been accepted. So it all becomes re-formatting. Since you have come all this way, did all this analysis, mulled over the results, written a great story, it seems like it’s a wearisome task to re-format everything. It’s painstaking, but just think, this is the last step to getting your degree!

I thought I would write about this because I’m at this point now in my thesis writing; my chapters are now either published or submitted. I’m so close to being done that I see the light at the end of the tunnel and it’s getting bigger (Figure 1). But I have been making observations about good practice for wrapping up your thesis and thesis writing that I hope any student or supervisor that reads may find handy. Most should be pretty obvious.

Figure 1 My workspace. Lucky to have big windows with lots of light.

Figure 1 My workspace. Lucky to have big windows with lots of light.

1- Start writing early. Have a “Final Thesis” file on your computer. This may/should seem obvious but write your methods as you go. You already (hopefully) have them written down in your notebook, why not type it up and have it ready, saved, in a “Methods” file. You can also work on a raw draft of your intro, save that into a “General intro” file, but for this you have to be flexible because sometimes projects change because a different direction may be more interesting. You can also start early on the “Acknowledgments”, the usual suspects will be in there anyway and fill it in as you go along with new colleagues as your program progresses.

2- Re-check your analyses. You always want to re-check your analysis. Especially if one of the chapters has been finished for a while, re-do the analyses to check whether you did it right the first time but to remind yourself of what you did. You never know, with all the new skills you have learned, you may have learned more appropriate analyses.

3- Try to minimize repetition. This is especially true for manuscript theses (the ones where chapters are written as separate papers). Because you thesis should have an overarching theme, each chapter will be linked to that theme and there will be repetition especially in each chapters introduction and (maybe) methods. Since your general introduction will cover the broader context, you should go into each chapter to reduce the repetition. It will make the thesis flow better. I think it’ll make your examining committee happier because they’ll have less to read and they’ll notice that they’re not reading things over and over

4- Keep it simple. We, as humans, have a tendency to want to look smart and use big words. Sometimes simpler words are actually the ones that convey the story you are trying to tell better. Of course you have to use appropriate terms for the field you study but there is no point in using big words for the sake of using big words.

5- Leave yourself a lot of time to write. A thesis cannot be written in a day, especially a good thesis. Like a good paper, it takes time to let the thesis develop. Be conscious that you will go through several drafts and don’t get discouraged that you have to re-write sections of your thesis.

6- Exercise and take breaks. At least go for a walk and get some air. Or to the gym to let out some steam. Your brain needs it.

These pointers are not huge Eureka moments, and there are more pointers I’m sure. But I think if you keep these in mind it’ll make your life through the writing process easier, your defense go more smoothly, your examining committee happier, and hopefully fewer edits in the final stage! I guess I’ll find out soon.

Leave a comment

Filed under Uncategorized

Another thesis chapter published

(I must first apologize for not posting anything sooner, but I have been very busy working on my thesis and manuscripts. I know it’s not an excuse but it’s the only one I have. So the following is one of the reasons why I haven’t posted earlier.)

The third of five data chapter of my thesis has been published in BMC Ecology with Wayne Knee and Mark Forbes as my co-authors (Mlynarek et al 2013).

This paper answers the question: does host geographic range explain measures of parasitism in the damselfly-water mite (external parasites) system (Fig 1).  The answer can be found in the title: “Relative geographic range of sibling species of host damselflies does not reliably predict differential parasitism by water mites”.

Figure 1 A super infected Enallagma erbium damselfly. The red dots on the thorax and abdomen are the water mites

Figure 1 A super infected Enallagma erbium damselfly. The red dots on the thorax and abdomen are the water mites

This paper/chapter is a continuation of the previous paper/data chapter where I tested the same question with gregarine parasites (internal parasites) in damselflies (Mlynarek et al 2012). Although in that paper, host geographic distribution actually explained the variation in gregarine parasitism at least half of the time. One of the main conclusions that can be made comparing these two projects is that different types of parasites (internal versus external) even in the same host species are explained by different factors.

So why don’t I say a little more about this most recent paper. Based on Mlynarek et al (2012) I expected similar results, the species with bigger geographic distribution will have higher numbers of parasites, but this did not happen. In this paper, I looked at 10 species grouped in 5 species pairs based on taxonomic classification. The results really surprised me, in only two of the five species pairs there was significant or near significant difference in the proportion of individuals parasitized between the species (Fig 2).

Difference in prevalence of water mite parasitism, the * indicates species pairs that showed significant differences in parsaitism

Difference in prevalence of water mite parasitism, the * indicates species pairs that showed significant differences in parsaitism

And in one of the two species pairs, it was the species with the smaller geographic distribution that had more parasites. As for intensity, or the average number of parasites individuals the infected host individuals have, only one of the species showed significant difference and again it was the less widespread species that had more parasites (Fig 3).

Difference in intensity of water mite parasitism, the * indicates species pairs that showed significant differences in parsaitism

Difference in intensity of water mite parasitism, the * indicates species pairs that showed significant differences in parsaitism

But we went a step further with this study and identified the water mites molecularly using the DNA barcode, cytochrome oxidase 1 (CO1) to see if we can get a handle about host ranges, or how many host species a water mite species can successfully infect. Based on our molecular analysis, we collected 9 Operational taxonomic units (or OTUs). Most of the mites OTUs seem to be generalist in that they infect more than one host species, but there are two specialists (Fig 4). You can see in figure that it’s pretty messy although there are tendencies for more closely related host species to be infected by the same water mite OTUs.

Host range of the 9 water mite OTUs infected 10 damselfly host species.

Host range of the 9 water mite OTUs infected 10 damselfly host species.

This made me realize that closely related species actually seem to have similar levels of parasitism. But it still makes me wonder whether there are host characteristics actually explain the variation in parasitism we see between host species at a broader taxonomic scale; that is yet another chapter of my thesis which I’m working on now.

References

Mlynarek, J.J., Hassall, C. and M.R. Forbes. 2012. Higher gregarine parasitism often in sibling species of host damselflies with smaller geographic distributions. Ecological Entomology 37: 419-425.

Mlynarek, J.J, Knee, W. and M.R. Forbes. 2013. Relative geographic range of sibling species of host damselflies does not reliably predict differential parasitism by water mites. BMC Ecology 13:50, doi:10.1186/1472-6785-13-50.

Leave a comment

Filed under Uncategorized