Teaching undergraduate students to draw phylogenetic trees: performance measures and partial successes

Young et al. Evolution: Education and Outreach 2013, 6:16 http://www.evolution-outreach.com/content/6/1/16 RESEARCH ARTICLE Open Access Teaching undergraduate students to draw phylogenetic trees: performance measures and partial successes Aimee K Young, Brian T White* and Tara Skurtu Abstract Background: An in-depth understanding of the process and products of evolution is an essential part of a complete biology education. Phylogenetic trees are a very important tool for understanding evolution and presenting evolutionary data. Previous work by others has shown that undergraduate students have difficulty reading and interpreting phylogenetic trees. However, little is known about students’ ability to construct phylogenetic trees. Methods: This study explores the ability of 160 introductory-level biology undergraduates to draw a correct phylogenetic tree of 20 familiar organisms before, during and after a General Biology course that included several lectures and laboratory activities addressing evolution, phylogeny and ‘tree thinking’. Students’ diagrams were assessed for the presence or absence of important structural features of a phylogenetic tree: connection of all organisms, extant taxa at branch termini, a single common ancestor, branching form, and hierarchical structure. Diagrams were also scored for how accurately they represented the evolutionary relationships of the organisms involved; this included separating major animal groups and particular classification misconceptions. Results: Our analyses found significant improvement in the students’ ability to construct trees that were structured properly, however, there was essentially no improvement in their ability to accurately portray the evolutionary relationships between the 20 organisms. Students were also asked to describe their rationale for building the tree as they did; we observed only a small effect on this of the curriculum we describe. Conclusions: Our results provide a measure, a benchmark, and a challenge for the development of effective curricula in this very important part of biology. Keywords: Assessment, Phylogenetic trees, Undergraduate education Background Improving students’ understanding of the underlying evolutionary processes that provide a framework for thinking about living organisms is an important goal of biology teachers and education researchers worldwide. As part of this, many researchers argue that evolutionary processes cannot be fully understood unless students are able to read phylogenetic trees and interpret the evolutionary relationships depicted therein (O’Hara 1997, Baum et al. 2005, Baum and Offner 2008, Omland et al. 2008, Perry et al. 2008). Phylogenetic trees are one of the * Correspondence: Biology Department, University of Massachusetts Boston, 100 Morrissey Boulevard, Boston, MA 02125, USA most important tools that evolutionary biologists use to record and synthesize information, explain phenomena and predict relationships among organisms (Novick and Catley 2007). For this reason, Baum et al. (2005) recommend that evolution education include clear and explicit instruction on building trees as well as on reading relationships and traits depicted in phylogenetic trees. Although a wide range of research has identified students’ difficulties with interpreting these trees (O’Hara 1997, Lopez et al. 1997, Meir et al. 2007, Novick and Catley 2007, Halverson et al. 2011, Perry et al. 2008, Sandvik 2008), only a few have explored students’ abilities to construct them (Staub et al. 2006, Halverson et al. 2011, Halverson 2011). Our research has focused on students’ © 2013 Young et al.; licensee Springer. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Young et al. Evolution: Education and Outreach 2013, 6:16 http://www.evolution-outreach.com/content/6/1/16 abilities to construct phylogenetic trees from a set of familiar organisms. We distributed a survey to 160 undergraduate introductory biology students at the University of Massachusetts Boston to determine how well they could depict the evolutionary relationships among these organisms. The design of the study allowed us to measure the effect of a laboratory study targeting tree-building skills on students’ abilities to draw trees accurately. The structure of their trees and classification of organisms were scored in comparison to scientifically accepted trees. In addition, we identified students’ rationales for creating their phylogenetic tree. Students’ prior knowledge Students come to the classroom with significant preexisting knowledge about the natural world and this knowledge informs their learning of evolutionary concepts. Two lines of research have investigated this in detail: investigations of folkbiology and naïve biology as well as investigations of students’ understanding of phylogeny. Folkbiology reflects how people understand the natural world and infer relationships among living things without formal instruction (Lopez et al. 1997, Coley et al. 1999, Hatano and Inagaki 1999, Medin and Atran 1999, Atran et al. 2004). Cobern et al. (1999) found that, even when students have formal instruction, they rely more heavily on their personal experiences with the natural world when asked about scientific concepts. Folkbiology is often informed by rich experiences with nature and can be influenced by one’s culture, location and prior knowledge (Atran 1999, Coley et al. 1999, Diamond and Bishop 1999, Hatano and Ingaki 1999, Ross et al. 2003, Medin and Atran 2004). Folk taxonomy, a subdiscipline of folkbiology, refers to the hierarchical nature of folkbiological classification (Atran et al. 2004) and tends to be culturally universal and resistant to change (Atran 1999). Both biological classification and folkbiological classification rely on direct contact and experience with plants and animals in the natural environment (Medin and Atran 1999). By contrast, naïve biology demonstrates a lack of experience with the natural world and is usually associated with urban populations (Hatano and Ingaki 1999, Atran et al. 1999). Both naïve biology and folkbiology are ways of interacting with and thinking about the natural world without the influence of modern science (Hatano and Ingaki 1999). Researchers can uncover the criteria students use for classification and the groups of organiams that students create by observing how naïve biology and folkbiology help students make predictions about relationships among organisms. Several studies have been conducted to compare the classification systems used by American undergraduates, who do not need to rely on ecological knowledge in today’s Page 2 of 15 industrialized world, and members of an Itzaj-Mayan culture, who are still dependent on the environment fo (...truncated)