Phylogenetic trees with horizontal bars were first used in the first edition of the textbook. In general, the placement of horizontal bars can be interpreted as horizontal relations between branches. Branches ending with a horizontal bar can also be interpreted as branches formed through diversification (for example, in Fig. 4, branches ending with a horizontal bar can be interpreted as the four species of the recently evolved Suidae). Of course, the presence of a horizontal bar on a branch indicates that the species represented in a branch diverged from its parent branch, while the absence of a horizontal bar indicates that the species in a branch share a common ancestor. In the first edition of the textbook, researchers Ben-Dov and Zuckerkandl (1963) described the horizontal bar as the most desirable shape for depicting phylogenetic trees and claimed that it shows relative distance of arguably equivalent taxa (Bromham 1972; Gregory and Burbrink 1971).
Based on the theory of evolution, phylogenetic trees are intended to be displayed. However, numerous efforts have been made over recent decades to resolve challenges in their use as other uses, such as decision support, have been attempted (Baum and Smith 2013). In general, the ability to display phylogenetic trees successfully facilitates the communication of concepts and processes in evolutionary biology among researchers and students because of the brevity and accessibility of a tree (Sprouse and Bailey 2012; Wiley et al. 2017).
Various novice-friendly modifications have been presented to phylogenetic trees to simplify their use and to enhance their use in education. Although no consensus has been reached, several modifications have been proposed, including the format modification of putting labels on trees to show not only the names of taxa but also its location in the tree. In addition, the use of different data representation models, such as with host web pages, schemata, and tree diagram, has been reported to facilitate the display of phylogenetic trees (Baum et al. 2005; Jones 2001). Other practices include arranging taxa in a tree at various levels of increasing taxonomic level (e.g., from phylum to order), using different types of symbols to represent different individuals and groups, and changing the chart format of phylogenetic trees. d2c66b5586