Community Ecology in Mesocosms
The end of the workshop has come, let the collaborations begin! We have learned a lot in the last few days (for example that ants grow bromeliads professionally in French Guiana and that Argentinian bromeliads look beautiful with under a blanket of snow). And I am sure we will do the most awesome joint analyses and global experiments ever. Thanks everybody for making this workshop a big success!
Foto: Olga Martinez
Inspired partly by the work of Cam Webb, Marc Cadotte, my former advisor Peter Kotanen, not to mention our own Nathan Kraft, I’ve been interested in studying the use of evolutionary history (phylogeny) in community ecology for quite some time. On one hand, understanding the relationships between organisms sometimes helps to predict their ecology, because phylogeny can correlate with ecologically relevant traits (some of which may be hard to measure). On the other hand, knowing how species interact in a community might help us understand why they diversified as they did (ie why there are not more, or fewer, species within a certain group etc)
However, I found I had less enthusiasm for the idea of doing large observational work with many species of plants (all the people mentioned above focus mostly on plants). Is it possible to manipulate phylogenetic diversity of animals? If phylogenetic diversity happens among plants and has strong bottom-up effects, why not top-down too?
I have two ideas; tell me if you think they’re nuts. First, I go to Brazil and set up small caged bromeliads. then inside each goes a few individuals of damselfly larvae, either of the same species or of mixed species. I restock the prey every once in a while and measure, measure, measure responses.
I know what you’re thinking! you’re thinking “But Andrew, what if you don’t find congeneric species?” and “But, how will you know which species are close relatives?!” the answer to the first is I’m hoping to find them (based on Diane’s data from Brazil, it should be possible) and to the second is maybe a collaborator will help to make the phylogeny of Leptagrion.
All this would be awesome if it works: but it might not. I have some contingency plans for Brazil (I’ll get to those in a later post) but I’ve been thinking it would be awesome to have a plan B. That’s where my Second Idea comes in: the phylogenetic ecology of Diving Beetles (Dytiscidae)
Three things set dytiscids apart from Leptagrion: they already have an excellent phylogeny, they occur in Canada, and I actually have practice identifying them. They also have three things in common: they are both insects, they are important predators in freshwater systems, and they are (hopefully!) easy to collect. Diving beetles are fairly diverse in Canada and most of all in BC where we have 173 species.
The plan is this: over the summer, drive around BC and collect diving beetles from lakes and ponds. Then, take them back to UBC campus and put them into cattle tanks (a very fashionable thing to do, cattletank experiments). I’ll stock some tanks with close relatives (let’s say, within a genus) and other tanks with more distant relatives (tribe, subfamily, etc etc). These tanks may or may not need mesh covers to keep the little guys inside (depends on who you ask). Then, I follow the example of the excellent experiment set out by Pavel Kratina and Hamish Greig: measure the experiments within an inch of their lives for every conceivable response variable that might be influenced by phylogenetic diversity of predators. Interesting problems: how do I avoid unrealistic communities (ie putting things together that never go together in nature) and control for body size (which will vary widely across communities)
What do you think, blogspace?
not JUST a random collection of letters!
Months ago, a Dr. Suttle of the Suttle lab (a lab on campus that seems to focus a lot on the ‘metagenomics of viruses’ and other such things) gave a talk about the role viruses play in determining ecosystem functioning in the global ocean. After the talk I was curious so I did some googling – sure enough, nobody knows anything really about the microbe communities of bromeliads. The closest thing was the papers on protists that Diane published with Thomas Bell.
Of course, we have our own mission to understand the microbe community: Pavel and Jana have undergraduate (s?) busily identifying protists which are preserved in lugol’s solution. I also have some tucked-away specimens which I thought I would one day identify under the scope.
But then, a guy from the Suttle Lab comes by my office and offers the idea of T-RFLP. Apparently, what one can do is amplify the sequence of DNA that codes for some Important Gene, using a primer that targets the genes of all protists/bacteria/viruses/whatever. Then, you ‘digest’ the stuff with an enzyme that cuts up the DNA whenever a certain special sequence occurs. Where exactly that sequence is will change depending on the ‘species’ of microbe. In the end, you get a pattern of peaks that reflects the diversity of the community.
Of course, there are complications: the same species produces many peaks, and the pattern of peaks of two different species can partially overlap. It is possible to figure out what actual species are in your community IF you have a ‘library’ of possible species to look for. Apparently this is distinct from ‘barcoding’, but I’d be hard-pressed to tell you why.
Anyway, apparently it doesn’t really matter that species identification is (or may be) impossible. Two different community samples will produce two different patterns of spikes. Since my hypothesis in my side experiment was about the similarity between communities – not the actual species composition – I think it should work fine. My idea is to get all these strange-looking patterns of spikes and do ordination (PCA or something?) to test the idea that one group of communities (those with a large mosquito predator) are more variable than others (those with a small mosquito predator).
Between me and this goal are all kinds of snags: the iodine in Lugol’s solution may have destroyed all the bacteria, plus iodine apparently snarls up DNA and makes PCR difficult. My molecular contact guy is very enthusiastic, but I know so little I can’t tell if he is underestimating how difficult this is. I don’t know if I’m getting into a one-week quick’n’dirty molecular thing (which would be great), or a massive project to pioneer the extraction of DNA from Lugol’s solution (not going to happen). The next step is to a) give it a shot this Friday and b) talk to other molecular biology (can you believe they call it “Mo-Bo”) types to get some second opinions.
Looking forward to it! I’m also looking forward to Jana’s reaction to hear I have abandoned the use of a microscope to identify protists. Just so you know, when my molecular point-guy came by my office today he suggested that a sample for T-RFLP should be preserved in the field with ethanol, not Lugols. He guessed 30%, but I haven’t googled about that yet. I’m willing to give this a shot if it might provide some fun data! watch this space for more details!
I know this is (or is supposed to be most of the time) a “scientific blog”, but I’d like to shed some light on another aspect of field biology: The food.
I feel that mostly field biology is supposed to be tramping around in the woods from dawn until dusk, climbing mountains, fording rivers, and surviving on some granola and oranges from your field pack. I once heard field biologists described as the jocks of the scientific world. As much as I hate to dispel the myth, the truth is that our work here in Costa Rica looks a little more like this: collect leaf litter and water from bromeliads, bring back to the station, and sit on the porch in shorts and flip flops for the rest of the day sorting through it. While we do have to go and find said bromeliads, most of them are not too far afield. (The other day I was at one of my field sites and I sneezed… someone in the kitchen said ‘bless you’ out the window). And now that the collecting is completed and various experiments are merrily ticking along with minimal supervision, what do we do at the station? We learn to cook.
I am not the cook in my family. My specialty is usually doing the dishes. But the number of things I have learned to cook from scratch while living at Pitilla station is rapidly growing! So far on the list is rice (trust me, I couldn’t do it before), bread/pizza dough, tortillas, plantain chips, cinnamon crepes, curry (more or less from scratch), and macaroni and cheese from scratch (I could do that before but certainly not unsupervised). This is the reason why most of us GAIN a few pounds doing field work rather than losing as we usually expect:
Wednesday
Breakfast: Cinnamon crepes with honey and maple syrup
Lunch: Rice and beans (of course) with fried plantain
Dinner: Chickpea curry with carrots, rice and sweet potato/potato/manioc hash browns
Thursday
Breakfast: Rice pudding with raisins, brown sugar, and honey with canned peaches
Lunch: Leftovers – curry, rice, and tortillas
Dinner: Plantain chips and fried queso seco appetizer, Macaroni and cheese and the obligatory beans
Friday
Breakfast: Fresh baked banana bread (thank you Jana!)
Lunch: leftover mac n’ cheese with garlic cheese bread, steamed broccoli, and beans
Dinner: Pizza and beer night! Pizza with dough from scratch, oven roasted garlic, and cervezas!
All supplemented by a steady snack diet of coffee and cookies and baby bananas with dulce de leche. mmmmm…
…It’s a tough job but somebody’s gotta do it!
The wonderful Encyclopedia of Life just added Dr. Erick Mata, from the National Biodiversity Institute of Costa Rica, as its executive director! So we have a new connection between Costa Rican ecological science – which is already the most awesome of any tropical country I’ve visited or heard of – and the world’s most ambitious online collection of biological information. Awesome!