Unit II - Populations
|Topic 6 - Classification: Concepts and Principles
Refer to Chapter 37
Taxonomy is the branch of biology that deals with the identification and naming of living things.
The main function of a classification system is to allow biologists to group organisms according to similar characteristics. This organization helps biologists study living organisms and to make predictions about their relationships, including structural information, biochemical information, cytological information, embryological information, behavioural information and fossil information.
The modern classification system is based on increasingly narrower (more specific) categories. The broadest category is the kingdom and the most specific category is the species. The categories from most general to most specific are kingdom. phylum, class, order, family, genus, and species.
Nomenclature is a term that refers to a system for naming organisms. In biology the system is "binomial" meaning that two names are used to specifically identify every organism - genus and species.
The binomial system uses a two word latin name to identify a specific type of organism. This is similar to the use of a first name and a last name to identify a person. The genus name and species name are the two words used. For example the binomial name for the fragrant water lily is Nymphaea ordorata. Notice that the genus name is always capitalized and the species name is never capitalized.
The five kingdoms used in modern biology are kingdom Monera, kigndom Protista, kingdom Fungi, kingdom Plantae, and kingdom Animalia.
The advantage of a five kingdom classification system is that there is far less overlap and confussion as compared to the original two kingdom classification system as proposed originally by Linneaus. There are still some problems with the five kingdom system and taxonomists are still working on improvements. One suggested improvement is to adopt a Domain system or a six kingdom system of classification.
The dichotomous system consists of a series of two point (paired) choices that deal generally with the presence or absence of characteristics that are easily identifyable in the organism. Each pair of statements in the dichotomous key gets more specific until the species is finally identified.