Journey into Phylogenetic Systematics

to Cladistics

of Cladistics

of Cladistics

The Need
for Cladistics

What is phylogenetic systematics, you ask? It is the way that biologists reconstruct the pattern of events that have led to the distribution and diversity of life.

There is an amazing diversity of life, both living and extinct. For biologists to communicate with each other about these many organisms, there must also be a classification of these organisms into groups. Ideally, the classification should be meaningful, and not arbitrary — it should be based on the evolutionary history of life, such that it predicts properties of newly discovered or poorly known organisms.

Classification, however, is only one aspect of the much larger field of phylogenetic systematics. Systematics is an attempt to understand the evolutionary interrelationships of living things, trying to interpret the way in which life has diversified and changed over time. While classification is primarily the creation of names for groups, systematics goes beyond this to elucidate new theories of the mechanisms of evolution.

Systematics, then, is the study of the pattern of relationships among taxa; it is no less than understanding the history of all life. But history is not something we can see. It has happened once and leaves only clues as to the actual events. Biologists in general and systematists in particular use these clues to build hypotheses or models of the history. We hope to convince you that only with a hypothesis of history can we truly discuss evolution.

But, before we begin this journey, hear this warning in the everlasting words of Father Jacobus (from Hesse's Magister Ludi):

To study history one must know in advance that one is attempting something fundamentally impossible, yet necessary and highly important. To study history means submitting to chaos and nevertheless retaining faith in order and meaning. It is a very serious task, young man, and possibly a tragic one.

Begin your journey by selecting one of the topics below.
"Introduction" is the first page in this module.

Introduction to Cladistics

Methodology of Cladistics

Implications of Cladistics

The Need for Cladistics