The model
"A smart model is a good model."
- Tyra Banks
While the world is on lock-down, I'm using my self-isolation as an opportunity to pursue projects that I wouldn't normally have the time for. I want to tell you about one of them, because it's a project I'm really enjoying.
Do you remember my dock study project from 2017? I spent a good 5 months collecting data from fouling panels in Woods Hole, in an attempt to understand how interactions between different species drive change in communities over time. When I started the project, I had very clear expectations in mind. Every paper I had read about New England fouling communities up to that point seemed to indicate the same thing: the first things to settle would be barnacles, followed by bryozoans and then ascidians. I had all sorts of hypotheses about how those species would interact, and I really thought my experiment would reveal a series of intricate, mechanistic species interactions driving succession.
Well, that's not what I found. The first things to show up on my panels were not barnacles by hydroids, and they took over all the panels. Other species started to settle, too, but they weren't able to really take off until water temperatures rose and the hydroids died off. Ascidians then began to dominate the community until early August, when they died off. In a twist of pure irony, barnacles were the last species to colonize my panels.
At the end of the experiment, I was utterly confused. None of my expectations had held true, and the mechanistic species interactions I had been looking for didn't seem to be there at all. I ended up wondering what was actually driving succession - was it new species recruiting, interactions between species, or water temperatures?
To answer these questions, I'm building a model. Essentially, a model is a simulation of whatever you're studying - in my case, succession in fouling communities. Using a series of probability functions, the model places "species" on "panels" and then makes them grow and interact over time. I'm basically building a virtual world using math.
The plan is to actually have a number of different models. One will include only recruitment, so "species" will settle on my "panels" but not grow or interact. In the second model, they'll recruit and grow but not be affected by temperature. In a third model, they'll recruit, grow, interact with each other, and die off when temperatures get too high. I'll see which model simulation produces results that match my data the closest, and that will tell me which factors have the strongest influence on succession in fouling communities.
Over the last week, I've actually made some progress! I'm able to simulate recruitment of several different species, using real recruitment data to define the probabilities in the model, and I was even able to make a figure! In the image at right, the grid represents a fouling panel; dark blue represents empty space, and other colors represent different recruits on the panel. I can keep track of their locations and abundances to see how well the simulation matches my real data.
I'm excited to develop the models and learn more about succession!
- Tyra Banks
While the world is on lock-down, I'm using my self-isolation as an opportunity to pursue projects that I wouldn't normally have the time for. I want to tell you about one of them, because it's a project I'm really enjoying.
 |
| The fouling community in Eel Pond in Woods Hole |
Well, that's not what I found. The first things to show up on my panels were not barnacles by hydroids, and they took over all the panels. Other species started to settle, too, but they weren't able to really take off until water temperatures rose and the hydroids died off. Ascidians then began to dominate the community until early August, when they died off. In a twist of pure irony, barnacles were the last species to colonize my panels.
At the end of the experiment, I was utterly confused. None of my expectations had held true, and the mechanistic species interactions I had been looking for didn't seem to be there at all. I ended up wondering what was actually driving succession - was it new species recruiting, interactions between species, or water temperatures?
To answer these questions, I'm building a model. Essentially, a model is a simulation of whatever you're studying - in my case, succession in fouling communities. Using a series of probability functions, the model places "species" on "panels" and then makes them grow and interact over time. I'm basically building a virtual world using math.
The plan is to actually have a number of different models. One will include only recruitment, so "species" will settle on my "panels" but not grow or interact. In the second model, they'll recruit and grow but not be affected by temperature. In a third model, they'll recruit, grow, interact with each other, and die off when temperatures get too high. I'll see which model simulation produces results that match my data the closest, and that will tell me which factors have the strongest influence on succession in fouling communities.
 |
| One example of a simulated fouling community |
Over the last week, I've actually made some progress! I'm able to simulate recruitment of several different species, using real recruitment data to define the probabilities in the model, and I was even able to make a figure! In the image at right, the grid represents a fouling panel; dark blue represents empty space, and other colors represent different recruits on the panel. I can keep track of their locations and abundances to see how well the simulation matches my real data.
I'm excited to develop the models and learn more about succession!
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