RESEARCH PROBLEM. A coherent framework appropriate for robust conceptual understanding of the concept of "adaptation" requires integrating descriptions and explanations. A description may be thought of a pattern -- what has taken place -- while an explanation may be thought of as a causal mechanistic process responsible for why that pattern exists. But a unique feature of biological sciences is that it offers descriptions and explanations at two broad levels: the proximate and ultimate (Mayr, 1961). For example, wood exists both because of (1) cell division in the vascular cambium (proximate), and (2) inter- and intra-specific competition for light over time (ultimate). While a large body of work examines student construction of causal mechanistic explanations, very few empirical studies examine the extent to which students provide descriptions or explanations in response to questions that contain answers at varying levels of biological hierarchy. Moreover, a common feature of student explanations is that they are often teleological in nature, but recent work distinguishes between two general flavors of teleological reasoning (Kampourakis, 2020; Trommler & Hammann, 2020) -- one uses the function of a trait as a causal justification for its existence (not legitimate), while the other simply identifies a trait in terms of its effect (legitimate).
STUDY DESIGN. To explore the extent to which students provide descriptions or explanations related to adaptation -- and whether they more commonly address the proximate or ultimate level -- I developed a framework built from typologies used in previous studies that organizes these concepts into a clear format that visually represents their relationships. This framework also accounts for legitimate teleological reasoning by distinguishing such reasoning as a description of the ultimate pattern. The framework has so-far been validated by a literature review focused on explanation and description in biology with emphasis on the concept of adaptation, and expert judgment. In addition, I developed a series of open-ended "why?" questions about adaptation that allow for varying levels of description and explanation (e.g., If penguins are unable to fly, why do they have wings?). I administered the questions as a pre-post assignment in four postsecondary biology courses, from introductory to advanced. The study spanned two semesters and included more than 600 students. I tallied the number of responses from each category of description and explanation both before and after instruction and compared the distribution of responses given by question, by major of study, by course affiliation, and by the number of earned biology credits. I also compared the distribution of responses between the pre- and post-assignments for each of the four variables.
ANALYSES AND INTERPRETATIONS. Roughly 60% of students provide ultimate-pattern descriptions in response to layered questions about adaptation. Of these, half invoke teleological reasoning appropriately while the other half do not. The overall distribution of descriptions and explanations invoked across the study does not differ statistically from the distribution observed when the data is examined by question, by major of study, by course affiliation, or by the number of previously earned credits. The observed distribution is also not statistically different between pre- and post-assignments. That is, the observed pattern is remarkably consistent. Moreover, to the best of our knowledge, only one study has empirically examined the extent to which students provide descriptions or explanations in response to "why?" questions -- and also reported roughly 60% of students provide similar descriptions (Riemeier, 2009). The results from this study suggest that the concepts of biological description and explanation and their various levels are potentially undertaught aspects in biology education.
CONTRIBUTION. Dobzhansky famously said that nothing in biology makes sense except in the light of evolution. It is therefore essential that our students can make sense of evolution, but doing so requires integrating lines of reasoning across multiple levels of biological hierarchy into a cohesive and stable framework. With that in mind, the proposed framework is valuable in that it clearly organizes the levels of biological description and explanation and integrates appropriate teleological reasoning. The framework has utility both as a tool for systematically assessing student thinking across levels of biological hierarchy, but also for the development of educational materials that could explicitly address these concepts in the classroom.
Libraries and preliminary HTML file created with the R package xaringan, built on remark.js. The rest was (poorly) hard-coded the old-fashioned way by me. See references.pdf for slide citations.
Most originate from RawPixel, an incredible resource of public domain images. (Found trawling the GitHub pages of @apreshill.)
- Swimming frog by Julie de Graag
- Sunflower (Zonnebloem) (1914) by Samuel Jessurun de Mesquita
- The Valley of the Nervia (1884) by Claude Monet
- Pinnated Gorgonia illustration from The Naturalist's Miscellany (1789-1813) by George Shaw
- Peacock (1925 - 1936) by Ohara Koson
- Lying bison (Liggende bizon) (1915) by Samuel Jessurun de Mesquita
- Fishing Frog or Angler (Lophius piscatorius) illustration from The Natural History of British Fishes
- Russell's Sting Ray (Trygon russellii) from Illustrations of Indian Zoology (1830-1834) by John Edward Gray
- Papilio laertes or Laertes butterfly illustration from The Naturalist's Miscellany (1789-1813) by George Shaw
- Augurkenplant (1898) by Theo van Hoytema
- Flying bat from Woodland Romances; Or, Fables And Fancies by Clara L. Mateaux
- Drie vliegende vogels (1878–1917) by Theo van Hoytema
- Two cockatoo and plum blossom (1925 - 1936) by Ohara Koson
- Beautiful photomechanical prints of Lotus Flowers (1887–1897) by Ogawa Kazumasa