The Biosphere is what we loosely call nature -- the Earth and its supporting atmosphere. All sciences ultimately study nature. Never-the-less, certain sciences focus more specifically on properties unique to our Biosphere. Foremost among these sciences -- from the perspective of this site -- is Taxonomy which examines, identifies, and categorizes the similarities and differences among all living beings.
Our world contains over 1.25 million distinct species of life ranging in size from microscopic bacteria to a fungus in Crystal Falls, Michigan estimated to weigh 100 tons. Between these extremes exists a very diverse range of living beings.
How does one begin to relate to this tremendous variety of life? 18th Century Botanist Karl von Linne -- or Carolus Linnaeus, as he preferred being called -- devised a classification system to address this very question. His system, with some modification, is still in use today.
The Linnaeus system has two main features: first a naming convention that allows each species to be identified by exactly two names -- the generic, or genus, name and the specific, or species, name -- and secondly, he devised a specialization hierarchy which classifies each living being into groups starting from the most general Kingdom down to the most specialized Species category. In between these levels are Phylum (or Division), Class, Order, Family, and Genus.
Linnaeus proposed only 2 Kingdoms: Plant and Animal. The changes in classification over time are best illustrated through the plant kingdom. Linnaeus classified plants according to their sexual parts -- the stamens and pistils -- and used such whimsical descriptions as "Public Marriages," "Clandestine Marriages" and "Husband and wife have the same bed" to describe the relationships between stamens and pistils.
In the 18th century, Linnaeus' "unnatural" system was replaced by the "natural" system of classification which considered all parts of the plant rather than just the stamens and pistils. Then the work of Charles Darwin on the evolution of species implied that there must have been more than two kingdoms. How else to categorize the "original species" which was both plant and animal? Insights provided by advanced microscopy provided further evidence suggesting the need to divide the Plant Kingdom.
Three systems of Botanical Classification, are now in favor. The Phyletic system attempts to reconstruct the evolutionary family tree of species through fossil records and functional similarities. The Phenetic approach groups all species according to a selected set of relevant features. Statistical methods are then applied to deduce the best way of grouping species based on these features. Cladistic approaches can be though of as a marriage of the previous two: they attempt to divine the evolution of species based on a statistical comparison of selected genetic features.
The system used for this site follows the Phyletic approach. We use the five Kingdom system described in 1960 by Cornell University Professor Robert H. Whittaker: Plant, Animal, Fungus, Bacteria, and Protoctist. We limit ourselves to the species an amateur naturalist would most likely concentrate on. This includes members of the first three Kingdoms and a small part of the Protoctist Kingdom (Seaweeds).
Modern day Taxonomy highlights our biological history. Many of the Phyla (the grouping just under Kingdom) contain very few living species: most of their species once "ruled" the Earth but are now extinct. The establishment of these Phyla help to expose the familial relationships among all living beings.
Taxonomic groups are differentiated primarily according to reproductive or "life-cycle" characteristics (newer techniques focus on genetic coding). Although these grouping often encompass gross structural similarities, the naturalist needs to know which structural aspects to focus on. See the introduction to the Plant Kingdom for examples.
In short, Taxonomy teaches us history, it helps us identify species, and it shows how livings things are related to each other in ways we might not have otherwise considered. Most importantly, by focusing our attention towards the details, we gain a much better appreciation for the intricacy, uniqueness, and beauty of all of our Earthly cohabitants.
Once in the field, the intrepid explorer will usually find that the Phylum/Division and the Family categories are the most useful Taxa for trying to identify a newly encountered species.
Ecology studies how living things get along together. If Taxonomy is a study of the history of life, then Ecology is the study of current events...
to be continued.
Page 5 of 38
This site produced and maintained by Ari Kornfeld, email: (email@example.com)
Copyright © 1996-2007 All rights reserved.
Please take a moment to provide your feedback on this site.