We were given an assignment in my research design class. Contemplate nature, our surroundings, and come up with as many scientific questions as possible and write them down – similar to a brainstorming session. The objective is not to come up with all great questions. Rather, by asking many questions we will likely ask 1 or 2 good ones. Once we had our questions, we were instructed to take our ‘best’ from which to generate several hypotheses and predictions. This exercise is important as one of the most difficult tasks for a scientist is generating good questions. I liked the assignment and decided it seemed like a perfectly good blog post as well.
I gathered a notepad and pen and journeyed out of town into the desert near Pyramid Lake in northern Nevada. I found solitude and inspiration in the view from the craggy hilltop where I settled in to my writing. I began to consider the idea of stochasticity and its role in generating patterns we see in nature. I began to think of concepts in astrophysics and what is understood of the formation of solar systems, galaxies, and ultimately the universe. Just after the big bang all matter that now exists in the universe was distributed homogeneously. Very soon after this, ‘primordial fluctuations’ produced density variations (i.e. heterogeneity) in this matter as it began to expand outward (and continues to do so!). These variations ultimately produced all the structure we observe in the universe today. There is no singular reasoning behind the placement of objects in the cosmos. Rather, it was stochastic processes early in the development of our universe that gave rise to the structure we see now. If we replicated this process many times over, we would likely find different outcomes each time.
This led me to think of the role of stochasticity on earth in the way environments, ecosystems and biotic communities form on earth. In particular, Hubbell’s neutral theory and functional equivalence in trophically similar species. In a nutshell, similar species are likely to share many common features and the success of one over the other is due to stochasticity rather than deterministic processes.
These two examples (the formation of the universe, and neutral theory within biological communities) are similar in their dependence on the role of stochastic processes in producing the structure and patterns we find in nature. Furthermore, we may find deterministic processes in the very same structure and patterns that have risen from these chaotic beginnings.
After a while of pondering these and other things, I starting to write down all the scientific questions that came to mind. They did not all have to do with stochasticity in nature. In fact, many had to do with entirely different concepts. Here are a few for example:
What role does the microbiome play in successful colonization and persistence?
To what extent do chemical landscapes dictate the movement and establishment of organisms?
And, here is one that I had fun with so I couldn’t leave it out!
How many definitions exist for non-native, or exotic species? And, at what scale may these definitions break down? Example: A careless astronaut finds a plant-like species on another planet and it finds its way back to Earth where it miraculously propagates in the Hakaluki Haor marshlands of Bangladesh. How may this lead us to re-evaluate our definition of “non-native” species?
If you care, the full list of questions is here.
The question I chose to elaborate on of course dealt with stochasticity in nature:
What deterministic and/or stochastic processes give rise to where and how riparian1 systems develop?
To set up the question, I got cosmic again and tried to formulate a thought experiment:
Imagine a Martian landscape with mountains rising miles into the air and vast alluvial fans below. Presently, no water flows on the surface of mars, and no plants or living organisms exist. Let’s imagine that water and life suddenly appear on the planet. Let’s go further and think of a large body of water on top of a Martian mountaintop. As the water begins to find its way down the mountain it will begin to carve out water courses. These water courses may grow larger as more water flows through, and some may even connect giving rise to even larger water ways, eventually becoming large creeks and rivers. If we were to recreate this scenario 1,000 times, we would likely find differences in the pattern and process each time. The question deals with the very beginnings of these ‘novel’ water courses. Why does water flow one way rather than another? What factors play a role in this? In an attempt to work through this set of questions2 I can think of a few testable hypotheses3 with associated predictions:
- The placement of plants on a landscape will influence the establishment of water courses.
- Early colonizing plants that can survive with little water will establish a community. The roots and structure provided by these plants reduces erosion and forces water to flow in adjacent channels. In effect, these early colonizing plants are the first inhabitants of a newly forming riparian ecosystem.
- More plants will continue to establish the newly forming riparian ecosystem, thereby reinforcing the effects against erosion.
- Engineered topology and geology will influence the establishment of water courses.
- A subtle difference in the topology of a landscape will lead to the movement of water courses in one direction over another.
- Similarly, differences in geology and the resistance of substrate material to erosive forces will lead to the distribution of water courses.
- The amount of water released will influence the establishment of water courses.
- A small but persistent amount of water will provide different outcome from a deluge of water.
- Why riparian ecosystems? Riparian means essentially “along a riverbank”. Riparian ecosystems are home to a large number of species across the globe. Since water is essential to life on earth, it is no coincidence that riparian systems are such cradles of life. But since water exists with or without life, it allows us to ask questions about the behavior of water with and without the influence of living organisms acting upon it.
- Among many other things, the scientific process relies on questions and hypotheses. A question is simply what it sounds like. For example, your car won’t start in the morning to go to work. A question would be: Why will my car not start?
- Hypotheses are more involved than just asking a question. Formulating a sound hypothesis is also very important to scientific pursuit. A hypothesis is a proposed and testable statement made to answer a scientific question. The key here is that it must be testable; experiments are used to test hypotheses. This is one area that clearly delineates science from pseudo-science. The corresponding hypothesis to our above-mentioned car problem could be: If I put gas in my car it will start. Can you think of any alternative hypotheses?