GENERATING QUESTIONS IN ECOLOGY
Scientific information is gathered by asking and answering questions. Everyone can ask interesting questions about the world around them. Moreover, with a little practice and the right tools, we can devise ways for answering the questions we ask!
There are several considerations related to asking scientific questions. First, it is important to consider whether or not the question falls within the realm of scientific inquiry. For example, questions about the nature of the human spirit fall beyond the scope of scientific inquiry. Typically, scientific pursuits are confined to the study of the physical universe, which includes living and nonliving parts.
Second, it is important to focus questions so that there is a reasonable opportunity to answer them given the appropriate tools and experience or background knowledge. For example, asking, "What is heat?" is a very broad question that does not easily lend itself to figuring out what kind of information is needed to answer the question. Yet it is possible to learn something about the nature of heat by focusing the question. Asking how plant growth is influenced by temperature does readily lend itself to scientific testing. A number of similar plants can be grown in different temperatures and compared in terms of height, weight, or number of seeds produced.
Ecology is the discipline of biology that is concerned with life at its highest levels of organization – the organism, the population, the community, the ecosystem. It is a scientific discipline oriented around understanding why plants and animals live where they do, how they interact, and what causes changes in their abundance. As you work through the labs and lectures of this course, you will see that ecologists are mainly asking these questions:
· How do animals behave and why to they behave this way?
· What species live in this place? Are they restricted to this particular place? And if so, why?
· How many species or individuals live here? Do these numbers change from place to place? Or from time to time? What was the abundance in the past? What will it be in the future? What factors govern changes in abundance?
· Which species interact with each other? How will increases or decreases in one species affect other species?
· How do species interact with or react to their environment? How do they obtain the resources they need? How do they find protection from threats?
· How do humans influence organisms?
Ecology has its roots in natural history, which can be described as the description of life: the identity of species, where they are found, and how they live. This is much harder than it sounds. Of the estimated 10-100 million species on Earth, less than 2 million have been described, and of most of these we know virtually nothing (Wilson 1993). Simply knowing the names of all the organisms in a forest or meadow is a difficult task! Knowing the names and characteristics of all the soils, plants, animals, fungi, etc. in a given habitat doesn’t tell us much about why those particular organisms are there, or how their abundances will change in the future, but this kind of knowledge is a necessary precursor to any ecological investigation. Natural history is an integral part of ecology, and a good ecologist will necessarily be a good natural historian. To be a good natural historian, you need to be a keen-eyed observer of nature. How then does ecology differ from natural history? As we said above, it is a scientific discipline. Whereas natural history is focused on description, ecology, like all other sciences, is guided by the process of scientific inquiry. This is just a structured way of building concepts by asking questions and getting answers. The process of scientific inquiry follows these steps:
1. Observation of an interesting phenomenon
2. Framing an answerable question
3. Proposing an explanation for the observation (a hypothesis)
4. Designing an experiment or study to test the hypothesis
5. Obtaining the data
6. Analyzing and reflecting on the data
7. Finally, communicating the results.
The first step is to make an observation – it is here that the link between ecology and natural history is most clear. It requires careful observation and a good knowledge of natural history to notice interesting phenomena. For example, on a walk in the woods, you notice that deer prints seem to be much more common in oak forests than they are in pine forests. The next step is to frame a question based on the observations. Of course, any observation will lead to all kinds of questions, and each of them may lead to interesting answers. The most difficult kind of question to answer is “Why?” The answer to the question “Why are deer more common in oak forests?” will surely be interesting, but it is difficult to answer directly because it doesn’t suggest any place to begin. There could be a large number of reasons that deer tend to be found in oak forests. Before you can proceed to the next step – designing the study – the question needs to be narrowed down a little bit.
To do this, the observation is combined with concepts, using resources such as the library, the Web, knowledgeable people, or your own imagination. For example, based on the information that acorns are much more nutritious and easily eaten than pine seeds, we might ask the question “Are deer more common in oak forests because of the greater abundance of acorns?” Questions like these lead naturally to testable hypotheses. A hypothesis is a general explanation for the observation that may (or may not) be true. A testable hypothesis is one that leads directly to predictions. In our deer example, we might phrase a hypothesis about deer abundance as follows: “deer congregate in oak forests because of food availability.” This statement leads directly to the prediction that, if true, we should find abundant evidence of deer only where there are abundant acorns, regardless of any other characteristics of oak forests. In turn, this prediction suggests ways of designing an experiment to test whether this is true. Framing a good question that leads to a testable hypothesis is really the most important step of the ones listed above. A testable hypothesis suggests naturally a means to decide whether it is true or not, and is the basis for any good study.
Simple rules for asking questions:
1. Questions must be answerable within a reasonable time limit. Questions such as "how?", "which?", "where?", "is there a difference?" are likely to be answerable. In contrast, "why?" questions, while often more intriguing, are rarely answerable in short time frames.
2. Questions must be comparative, and the comparison must have some basis or general context involving common sense and logic or some prior knowledge of general concepts that would lead one to expect the comparison to yield a difference. A comparative question forces the inquirer to think about the question and leads to reflection, where as a non-comparative question is often a dead end. An example such as, "How many insects are in the leaf litter in that shaded comer next to the biology building?" is a non-comparative question. Its genesis doesn't involve a broader significance of the results found. The question, "Are there more insects in the leaf litter in this shaded comer than in that one?", is a comparative question but, it does not involve any particular broader reason for making the comparison. In contrast, the question, "Are there more insects in the leaf litter in the shaded corner than in the sunny corner?", is a truly comparative question with a broader conceptual framework. Here the two questions are specific examples of much broader categories of places and much broader concepts (sun = hot, dry; shade = cool, moist, maybe little crawly things prefer, or survive better, under one set of conditions better than another, which would mean that here there should be more insects in ... ).
3. Questions must be somewhat tantalizing, that is, they must involve neither an overly tedious procedure nor an overly obvious predetermined answer. A question that otherwise complies with rules 1 & 2 could still be a downer if (a) the answer is blatantly obvious or predictable at the outset; or (b) if the answer is non-obvious but the tedium of the data collecting necessary to answer the question far overwhelms the thrill of the chase and the potential for reflective learning. Example of (a): "are there more insects in this leaf litter in the shady comer than in the paved parking lot?". Example of (b):"Is the average size of leaves on this 30 m tall poplar tree different than that 22 m tall poplar, sampling 1000 leaves per tree at random?".
Once a hypothesis is proposed, and the predictions made, the next step is to test the predictions. This step involves carefully designing an observational study or experiment to decide whether the hypothesis is true or not. After the study is designed, we carefully collect the data and analyze them. The next step is to reflect on what our data mean. Of course, we want to know whether our results support our initial hypothesis, but its important to reflect as well on the other steps too, such as whether the study was designed correctly or whether the data were collected without bias. Finally, after we have completed our study and thought hard about what the data mean, the last step is to communicate as clearly as possible the results of this process to the larger world, so that others can benefit from our experience. In this class you will gain experience with communicating your results in both written and oral form.
In the process of answering our original question, we are sure to generate all sorts of additional questions, and if we’ve communicated our study well, questions will occur to other researchers as well. Thus the whole process starts again (Figure 1). This structured form of inquiry is what makes natural history into the science of ecology. We will apply these steps to assigned projects, and to projects of your own through the course of the semester.
FORMULATE YOUR OWN QUESTIONS:
On your own, find some quiet areas outdoors where you can sit (or stand) comfortably. Generate at least 20 questions related to the plants, animals, and physical environment around you. Jot down the questions as they occur to you without mentally editing them.
DESIGN EFFECTIVE EXPERIMENTS:
Choose the single question on your list that you think is most interesting. Use about 20 minutes to think about how you would test this question, and how you would rule out viable alternative hypotheses.
Documenting the pattern. First, you will want to figure out ways to formally document the pattern you observed. Often, one’s impression of a pattern will not stand up in the face of actual data, and who wants to waste time doing experiments to test a pattern that doesn’t exist? This is why formal documentation of a pattern is the first step in designing effective experiments.
Keep in mind that documenting the pattern does not establish causality. For example, showing that two species of frogs never occur in the same place does not mean that they are so distributed because they compete for resources (or did compete for resources). You would be surprised by the number of practicing ecologists who have made the mistake of confusing correlation with causation.
Experimental ecology. Next, try to think of ways to manipulate the system to isolate the factors that you think may be important for determining the pattern you observed. A note of advice: the most effective experiments alter only one variable at a time, holding all other variables constant. In light of this fact, you may want to think about the appropriate controls for any manipulations you propose.
We will meet back in lab to discuss some of your questions and how they might be tested using the scientific method.
YOUR ASSIGNMENT (due in lab next week)
Write a 1-2 page (single-spaced, 1-inch margin, 12 point Times New Roman font) summary of this exercise. Start with a paragraph that sets-up your most interesting question by describing why you think it is interesting from an ecological perspective (3-4 sentences). Next, state the question for which you designed an experiment during the lab. Also, state the null hypothesis for your question. Finally, in a paragraph or list describe the steps you would take to test your hypothesis of interest: both to formally document the pattern you observed, and to experimentally manipulate the system in order to isolate a factor of interest.