Improving Tree-Thinking One Learnable Skill at a Time

Abstract

Representations are a critical way to communicate scientific knowledge. Systematists biologists are acknowledged as expert tree thinkers who can both read and build phylogenetic trees (e.g., cladograms) accurately. The purpose of this study was to identify the core skills essential to help college students overcome tree-thinking challenges. In this study, I used pre/posttests, interviews, weekly reflective journal entries, field notes from course observations, and student responses to coursework to learn how upper-level college biology students developed representational competence with phylogenetic trees. I identified essential core skills by investigating students' tree-thinking progression over the course of the semester. Three major patterns emerged from the data: (1) students became better tree readers than tree builders by the end of the plant systematics course; (2) core skills are essential for students to develop tree-thinking competence; and (3) tree reading skills developed before tree building skills. By diagnosing challenges students face with tree-thinking, identifying core skills necessary to overcome these challenges, and developing a starting point for a context-based framework for representational competence, this study adds to our understanding of critical elements necessary for designing effective instructional interventions and improving student learning with phylogenetic trees.Keywords Tree-thinking . Cladogram . Phylogenetic tree . Challenges . Core skills . Representations . EvolutionPeople use representations to explain how we make sense of things on a daily basis. Often biologists generate phylogenetic representations to express their understandings of the evolutionary relationships they are investigating (Matuk 2007). In systematic biology, biological information is organized using phylogenetics and "evolutionary trees serve not only as tools for biological researchers across disciplines but also as the main framework within which evidence for evolution is evaluated" (Baum et al. 2005). Evolutionary biologists interpret phylogenetic trees in accordance with how they illustrate evolutionary histories or inferred evolutionary relationships among a set of taxa (Baum and Offner 2008). Scientists compare phylogenetic representations in search of similar patterns to provide support for hypothesized relationships among taxa. They find similarities by comparing monophyletic groups, or clades, across representations. Being able to correctly interpret and compare phylogenetic trees is a critical component to developing tree-thinking.A second component of tree-thinking involves generating phylogenetic trees by isolating and interpreting informative data into evidence of evolutionary relationships. There are many different styles of representations an expert could generate if asked to draw a visual representation illustrating the relationships among taxa (e.g., Matuk 2007). In addition, scientifically accurate phylogenetic representations share the following features: relationships are gr...

Correlations Between Tree Thinking and Acceptance of Evolution in Introductory Biology Students

“…Errors detected in pretests, such as not knowing that a phylogeny shows relationships among taxa or that there is a time axis inherent in a phylogeny, indicate that some students have a fundamental misunderstanding of phylogenetic trees and the information they contain. Other errors, such as reading across the tips and node counting, indicate how students who have not been instructed how to correctly read trees use superficial features to interpret phylogenies (Halverson 2011). After completing the different activities and modules, however, students' ability to read and interpret phylogenetic trees was significantly improved (Tables 2, 5).…”

“…In addition to providing a diagnostic tool to identify students' misconceptions about evolution, tree thinking can also serve as an organizing concept that connects different forms of data that serve as evidence of evolution. Thus, there are reasons to suspect that improved tree thinking might foster greater acceptance of evolution in undergraduates (Alters and Nelson 2002;Nehm et al 2009;Halverson 2011).…”

Investigating the relationship between college students’ acceptance of evolution and tree thinking understanding

“…Unfortunately, trees are difficult for students as they have substantial visual conventions that are not particularly intuitive for novice readers ) (for example, Halverson et al 2011;Gregory 2008;Naegle 2009;Perry et al 2008). Poor content understanding, along with the non-intuitive nature of trees, can lead to students misinterpreting branching structures (Gregory 2008;Halverson 2011;Halverson et al 2011;Novick and Catley 2012). These difficulties only add to the challenge of changing students' ideas about evolution (for example, Bishop and Anderson 1990;Demastes et al 1995;Nehm and Reilly 2007).…”

“…Evolution is a central organizing principle of the biological sciences (American Association for the Advancement of Science (AAAS) 1993, 2011Bybee 1997;Kagan 1992; National Association of Biology Teachers (NABT) 2010; National Research Council (NRC) 1996), and provides explanations for practical phenomena such as antibiotic resistance, the artificial selection of domesticated animals and food plants, and the diversity and history of life (AAAS 2011). Although there is little to no controversy surrounding evolution in the scientific community (Alters and Alters 2001), acceptance by the American public is largely lacking.…”

Penser la biologie dans un cadre phylogénétique

“…Notre expérience d'enseignant-chercheur nous a appris qu'au-delà des difficultés réelles qui existent pour bien comprendre les méthodes employées, peu familières à la plupart des biologistes, le problème récurrent le plus grave est la mauvaise compréhension de la méthode de lecture des arbres. Dans les copies de nos étudiants, nous retrouvons régulièrement des erreurs bien identifiées [14][15][16] qui sont dues à la persistance du concept obsolète d'échelle des êtres (scala naturae) [17]. Malheureusement, ce biais d'interprétation des arbres phylogénétiques est Les arbres phylogénétiques permettent de décrire de façon très synthétique et facile à lire les deux principaux processus de l'évolution : (1) l'anagenèse ou évolution dans une lignée qui est représentée par une branche, et (2) la cladogenèse ou spéciation, qui est représentée par un noeud d'où sont issues deux espèces à partir d'un ancêtre commun.…”