Friday, 29 June 2007

The Tree of Life Web Project - review and quick start guide

The Tree of Life Web Project sets out to catalogue the species of the Earth, and their evolutionary relationships to each other. It isn't complete, but still contains huge amounts of information. Still, the incompleteness can be frustrating when it relates to something you wanted to look up. And using the tree may take a little getting used to. There are huge numbers of groups of species (clades) with names little known to most lay people. The Tree of Life was originally intended for biologists, and it is only slowly expanding to suit other users. I found the documentation provided by the Tree of Life of limited helpfulness. But it's still an amazing resource, and it grew on me as I kept thinking of things to do with it. Below are a list of mini-investigations using the Tree of Life, that might help some people get started.

What is a phylogenetic tree?

Before exploring the Tree of Life, by yourself, or with children, you might want to know what it is? A good basic guide to understanding what a phylogenetic tree does can be found here, at Berkeley's Understanding Evolution site.

Find human beings from the root of the tree

A first, and very simple exploration within the Tree of Life.
  1. First go to the root of the Tree of Life.

  2. From there, click on the following links to navigate through the Tree of Life to Homo Sapiens:

    Eukaryotes | Animals | Bilateria | Deuterostomia | Chordata | Craniata | Vertebrata | Gnathostomata | Sarcopterygii | Terrestrial Vertebrates | Amniota | Synapsida | Therapsida | Mammalia | Eutheria | Primates | Catarrhini | Hominidae | Homo | Homo Sapiens

    By scrolling down the Homo Sapiens page to Information on the Internet, you can find a large number of resources on human ancestry and human beings in general. Or you could just admire the image of Charles Darwin as an example of a European male.
Finding the species you want:

For most investigations, you will need to home in on a species or group near the outlying parts of the tree. Type the name of the species into the search engine in the top right hand corner. The common name might get you the answer you want, but in practice, I've found the scientific name works better. The easiest way I know to get the scientific name of most species is to look them up in Wikipedia.

There is a further issue: the Tree of Life isn't down to species level in many places, so you may have to choose a broader family name. There are also minor mis-matches between some names used on the Tree of Life and those given in Wikipedia, and there are lots of extra levels in the Tree.

Trace a species backwards through the Tree:

  1. Type the name of your species into the search box in the top right hand corner. I wanted to trace the Swallow, so I typed in the family name Hirundinidae.

  2. The search engine offered the page Sylvioidea, on which the Hirundinidae appear as a branch. The tree currently goes no further than this, so it's lucky I didn't try an individual species name.

  3. From here, it's easy to trace the species back through the tree, by clicking on the arrow to the left of the tree diagram. In some places, there is no tree, but a list of species. In this case there is a Containing Group label under the list instead. Here is the list of pages for Swallows.

    Hirundinidae | Sylvioidea | Passerida | Oscines | Passeriformes | Neoaves | Neornithes | Aves | Coelurosauria | Theropoda | Dinosauria | Archosauria | Archosauromorpha | Diapsida | Amniota | Terrestrial Vertebrates | Sarcopterygii | Gnathostomata | Vertebrata | Craniata | Chordata | Deuterostomia | Bilateria | Animals | Eukaryotes | Root

    By default, the section under the tree diagram on most pages discusses the phylogenetic relationships. You can find out whether they are controversial and what they are based on. In the case of Swallows, I discovered that Passeriformes can be generalised as perching birds, while the sub-group Oscines are what we commonly call song birds. Below this are the references, which could be useful for research projects at higher levels.
Find out how closely related two species are

At first I thought I would try to trace the relationship between the Dandelion and the Daisy, but I gave up, as this part of the tree seemed very incomplete. I settled instead for the Ladybug and a common European beetle, the Gendarme. These are very superficially similar in appearance, being red with black markings, just close enough to sometimes be confused by very young children.
  1. Just trace each species backwards through the tree, until you reach a point where their ancestry is identical.
Coccinellidae (ladybugs) | Ccujoidea | Cucujiformia | Polyphaga | Coleoptera | Endopterygota | > Neoptera - turning point < | Hemipteroid Assemblage | Hemiptera | Heteroptera | Pentatomomorpha | Pyrrhocoroidea (gendarmes)

Neoptera is the containing group for both species, and since it contains rather a large proportion of all insects, that would make them pretty distant cousins. It would be interesting to know whether they adopted the same colour scheme for the same reasons, and whether they use the same chemicals to produce it.

Research a related group of species

If the tree has been completed for the species you are interested in, you could obtain: a list of related species, information about how they relate to other groups, and access to other resources on the Internet. At first I thought I would look up deer, since I remembered wondering how many kinds there are. I found the Cervidae under Ruminantia, but the tree hasn't been extended any further as yet. So I reverted to Penguins (Spheniscidae).

This time I struck gold, since there is a page for the Spheniscidae family with resources, and one for each individual species, with more resources, including several aimed at children or educators. By going up the tree, I can also see that the penguin branch separated from other birds at a fairly early stage - but after ducks!

Find out more about the Tree of Life

About the Tree of Life Web Project
The TOL Learning Tour
The Introduction to Learning with the TOl - a class project
The TOL Learning pages

You will find plenty of information about treehouses on the last page. This is an opportunity to work with the tree of life that is potentially of interest to homeschoolers, though it is not clear how active it is at the moment. The site promises modifications to make it more friendly to child-learners in the near future.

1 comment:

Erik Haugen said...

TOLWeb is a disappointment. You outlined some of the problems, but a bigger one is that it is horribly out of date. For example, the page for eutheria is completely wrong: It's a shame, because it's such a beautiful site and a great interface and concept. It's interesting to see how wikipedia has excelled in all the ways that TOLWeb has failed. The bottom line is that TOLWeb only allows credentialed scientists to contribute to, for example, the structure of the trees. Apparently credentialed scientists have better things to do - allowing enthusiastic amateurs to contribute seems to result in a much better product: more accurate and more complete.