The Ecology of Death: Forensic Entomology as a Teaching Tool
McNeil, James, The American Biology Teacher
One of the challenges in science education is making complicated topics interesting and relevant to students' experiences, particularly in the case of concepts that span large geographic or temporal scales. One such topic that I cover in undergraduate nonmajor science classes is the concept of ecological succession, or the patterns of change seen in communities of organisms following a disturbance (Gibson, 1996). This concept has been identified as one of the key components of fostering ecological literacy in American biology students (Gibson et al., 1999; Morrone et al., 2001); however, it is often difficult to convey to students why understanding successional patterns is important. Students perceive succession as something that happens in extraordinary circumstances (i.e., after a fire or large natural disaster) or happens so slowly that it has no relevance to their lives. Using smaller-scale examples can help students understand that succession is occurring all around them and on relevant time scales. In my classes, I use the example of forensic entomological succession to illustrate the larger concept of ecological succession. Even though forensic succession is a new topic for many students, discussing it teaches them about an important ecological concept at a manageable scale and can be used to explore some of the other underlying factors that drive succession.
Entomological forensic succession was described using the theories of ecological succession, so it is very relevant to the topic (Dadour et al., 2001). Although it is a relatively small field, forensic entomology has received increased media attention in recent years because of the success of television programs like CSI: Crime Scene Investigation. The exposure in the popular media has made the study of insects for solving crimes more accessible to students, and I am often surprised by how much they know about the subject before coming to class. This prior knowledge, coupled with the intrinsic fascination most students have for the subject, allows me to connect forensic entomology to the more abstract topic of ecological succession in a meaningful way. Many of the same mechanisms that drive succession on an ecosystem scale (i.e., abiotic factors, predator-prey dynamics, and environmental adaptation) operate on the level of insects colonizing a cadaver. Because of the smaller spatial and temporal scale, it is easier to explain to students how these factors influence the success of different organisms as the resource changes, which makes it easier for the students to grasp the importance of succession in the context of other ecological principles.
Although I most often conduct the following exercises in college-level introductory courses, I have also used them with children as young as eight at summer science camps. It is important to consider the level and maturity of the class before using these exercises and to craft the discussion appropriately given the sometimes graphic visuals associated with forensic entomology.
I begin the exercise by defining ecological succession. I explain how different plant and animal groups are able to colonize a disturbed area through their interactions with the physical environment and the organisms already present there. Using images and illustrations, I present the classic large-scale examples of a forest after a fire or the aftermath of a volcanic eruption. Specifically, I mention Mount St. Helens in Washington, where an eruption in 1980 catastrophically disturbed the old-growth forest surrounding the mountain. Gary Rosenquist, an amateur photographer, captured images of the first few moments of the eruption, and these pictures are an excellent hook to catch students' attention (Tilling et al., 1997). Because a volcanic eruption is a very drastic example, it can also be informative to use local examples, such as new construction in the town or on campus. …