Full Director's Commentary

Assigned Problem
Our assignment was to compare and contrast the tree, bush, and ladder metaphors of organizing biodiversity and evolution. We were also asked to discuss the implications that these metaphors create. Required reading: Infinite Nature, Chapter 3 pg. 29-32.
Rational
We decided to break down and define each metaphor, following with a skit that dramatized the implications that we felt each metaphor created. We began with the tree and ladder metaphors which we felt wrongly imply that humans are superior and more evolved than all other species. Lastly, we discussed the bush metaphor which we felt was an accurate metaphor for arranging biodiversity and evolution.
Five Points
The five points made in the video that were connected to points made in class discussions and the book are as follows. The first of these was the idea of using a ladder model as a means of organizing the various levels of biodiversity. This idea places different organisms on different rungs of the ladder, increasing with complexity as you move up the ladder. Humans are placed at the top of the ladder. The second theory proposed is that of the tree. The tree demonstrates how all species originated from a single ancestor, the trunk of the tree, and the branches emanating from them are all the organisms that ever existed. The branches that abruptly stop are those that have had a particular species go extinct, and the branches that reach the outermost part of the tree that bud and have leaves are those of organisms that are present today and are still evolving. The final theory that is set forth is one that depicts a juniper bush as the best representative of how organizing biodiversity should be approached, and that is in a way which shows how the intertwined and twisted branches sprawl with no noticeable purpose representing how all organisms are related and part of a bigger, interconnected web of life. Another point that is brought up in the video is the question of why, in most of the organizational processes of biodiversity, is the human race thought of as the pinnacle of evolution. Granted there are some aspects that do place humans towards the top such as the ability to communicate through language, to reason, and to adapt to different situations and create a widespread population, but there are animals that have actually evolved more than we have such as the Bonobo chimp. This is why there is skepticism as to why humans are presumed to be at the top. A final point that was made was the opposition to the idea that all organisms are evolving into a better form. This is a misconception that many fall prey to. The fact is that evolution happens by random mutation and chance and the results of this may not necessarily be for the better for a species survival.
References
Avise, John. “Three Ambitious (and rather unorthodox) Assignments for the Field of Biodiversity Genetics”. National Academy of the Sciences. 2009. http://books.nap.edu/openbook.php?record_id=12501&page=281 5th November 2009.
Rosenberger, Alfred. “Charles Darwin lll, Descent With Modification”. Vision Learning Vol. Bio-2 (5). 2004. http://www.visionlearning.com/library/module_viewer.php?mid=112. 5th November 2009.
Baum, David. “Trait Evolution on a Phylogenetic Tree: Relatedness, Similarity, and the Myth of Evolutionary Advancement”. 2008 Nature Education. http://www.nature.com/scitable/topicpage/Trait-Evolution-on-a-Phylogenetic-Tree-Relatedness-41936. 5th November 2009.
Kull, Kalevi. “Ladder, Tree, Web: The Ages of Biological Understanding”. Department of Semiotics, Tartu University. http://www.zbi.ee/~kalevi/kull312.pdf. 5th November 2009.
Malamud, Randy. The Chronicle Review 2008. http://forum.eol.org/viewtopic.php?f=1&t=31&view=previous. 5th November 2009.

The first source was used as a reference for the tree metaphor. It argued that if you include fossils in the tree it turns more into a web.
The second source deals with Charles Darwin’s view of biological diversity. He includes a tree-like metaphor in his book “The Origins of Species”. It is the only illustration in this book.
In the third source Baum talks about how the tree metaphor can evolve and change and really goes through the mechanics of the tree metaphor.
The fourth source goes over the tree, ladder, and web models. It goes into detail on each one and even gives some background on where they came from.
The fifth source goes over how humans affect the ladder and tree metaphors. It also gives examples on how humans affect the environment.