Phylogenetic Trees

A phylogenetic tree is a graphic attempt at representing the phylogeny of a any group of taxa.

At this website, I break with tradition in the making of phylogenetic trees, at least for the time being. Although I am not currently utilizing this style, I believe the optimum trees are represented by a simple style called the phenogram. This style, discussed more later, seems to myself at least, the most intuitive of the attempts at graphical representation of phylogeny. In my limited experience however, these trees also seem difficult to construct with the medium of web-building software.

One program for constructing trees that I have found on the web is called Drawgram is written by by Joseph Felsenstein (Copyright 1990-2008 by The University of Washington). A few styles of trees, other than the phenogram, that this program can make are the cladogram, where nodes are connected to other nodes and to tips by straight lines going directly from one to the other, giving a V-shaped appearance; the curvogram, using elliptical curves; the swoopogram, also using elliptical curves; the eurogram, popular in Europe and similar to the phenogram other than having half of its lines diagonal; and the circular tree, where the tree grows outward from a central point.

Another style of tree I will here give the tenative name "dropogram" to reflect how all daughter taxa are inserted below their parent taxa (as opposed to at the side as in a normal phenogram). Here is an example:

The style that I will here give the tentative name "boxogram" is the one I have decided to use at this website. Although I have been unable to locate other uses of this style of phylogenetic tree, it seems to be simple enough that most everyone can understand its intent. The primary reason I use these trees at Project Linnaeus is that they are easy and very time-efficient to construct, most assuredly a strong benefit when setting out to construct a website based largely around these diagrams. Simple tables of their variety are also easy to transfer to other programs.

Phylogenetic trees can also be read horizontally or vertically, rooted or unrooted.

Considering types of phylogenetic trees that can be drawn by hand, many other types become notable, especially a classic style of tree representation called the Dahlgrenogram, named after Rolf Dahlgren.

Explanation of my "boxogams"

Caninae			†Leptocyon
	Vulpini		†Metalopex
			Urocyon
			Protocyon
			Otocyon
			Vulpes
	Canini	Cerdocyonina	†Theriodictis
			†Protocyon
			Dusicyon
			Pseudalopex
			Chrysocyon
			Cerdocyon
			Nyctereutes
			Atelocynus
			Speothos
		Canina	†Eucyon
			Canis
			†Cynotherium
			†Xenocyon
			Cuon
			Lycaon

A boxogram for the subfamily Caninae is shown above. It is important to read these diagrams horizontally, i.e. the diagram shows the more inclusive groups to the left side and all of their daughter taxa appear in boxes to their right. A cell without a label may be thought of as an unnamed taxon. Note the two genera Cuon and Lycaon at the bottom right of the diagram. These two genera are represented here to be more closely related to one another than either of which are related to any other taxa on the page, thus they form a clade, which would be represented by the empty cell to their immediate left. That clade is in turn more closely related to the unnamed clade that contains Cynotherium and Xenocyon than it is to any other clade on the diagram. Within the charts, all taxa accepted as monophyletic clades are shown in italics. Paraphyletic or polyphyletic groupings will be written in standard font in quotation marks (i.e. "Fish"). Blue text, of course, represents a hyperlink.

Anagenesis may be represented in a boxogram by having two cells adjacent horizontally that are the same height.

In the future, I would like to use phenogram style phylogenetic trees with a background a geological timescale, showing points in time in which divisions between taxa have occurred.