4.1.1 classification schemes

Biodiversity and continuity

Classification schemes

Image of classification:

http://www.tutorvista.com/content/biology/biology-iii/animal-kingdom/animal- classification.php

AP Biology: Microbe evolution and classification video

http://outreach.mcb.harvard.edu/materials.htm

Artificial classification systems, such as the grouping of vehicles into those that provide transport on land / water / air etc., are based on arbitrarygroupings and have little meaning. The biological classification system, however, is based on research in biology, chemistry, genetics, etc. It is a scientific method of classification used in biology to group similar organisms that share commonfeatures and is and is more universally accepted.

It is always necessarily hierarchical where the important features inherited from a common ancestor determine the group in which the organisms are placed.For example humans and whales both feed their young on milk and it is a characteristic inherited from a common ancestor which places them under thesame class “mammals” even though their habitat is completely different.

Each organism is grouped into one of 5 large groups or kingdoms , which are subdivided into smaller groups called phyla (singular: phylum) and then smaller and smaller groups with other names.

Kingdom

Phylum

Class

Order

Family

Genus

Species

History of classification

Aristotle a 4th century (384 to322 BC) Greek philosopher divided organisms into two main groups namely plants and animals. His system was used into the 1600's. Peoplewho wrote about animals and plants either used their common names in various languages or adopted more-or-less standardized descriptions. Caspar Bauhin(1560–1624) took some important steps towards the binomial system by modifying many of the Latin descriptions to two words.

Carolus Linnaeus (Carl Von Linne) was an 18th century (1707–1778) Swedish botanist and physician. He classified plants and animals according to similarities in form and dividedliving things into two main kingdoms namely - plant and animal kingdoms. He named the plants and animals in latin or used latinised names in his book Species Plantarum (1753) and Systema Naturae (1758).

You can watch a video about Carolus Linnaeus at Photo of Carolus Linnaeus http://www.youtube.com/watch?v=Gb_IOSzLgk&feature=related

Since Latin was once the universal language of science among western scholars in medieval Europe these names were typically in Latin. Latin is used to name andclassify living organisms, since it is a dead language - it’s no longer changing and is regarded as international.

His classification system is still used today; however, we use a five kingdom system instead of two kingdom system.

He designed a scientific system of naming organisms called binomial nomenclature ("bi-two, nomial-names”. He gave each organism a two part scientific name - genus (plural = genera) and species (plural = species) names. The genus and species names would be similar to your first name and surname. Genus name is always written with a capital letter whereas species name is written with a small letter. Species name belongs to that specific type of organism which are only able to interbreed and produce fertile offspring. Thescientific name must always be either underlined or written in italics.

For example the scientific name of the African elephant is...

Genus Species

http://www.flickr.com/photos/12333120@N00/3679975496/sizes/l/in/photostream/

An organism will always have only one scientific name even though they might have more than one common name. For example – Blue crane, indwe (foramaXhosa) and mogolori (for Batswana) are all common names for South Africa’s national bird. However, it has got only one scientific namewhich is Anthropoides paradiseus.

The scientific name of our human race is Homo sapiens . We are the only surviving members of the genus Homo – other more ancient / ancestral types have all become extinct, such as Homo ergaster and Homo neanderthalensis.

Prokaryotes and eukaryotes

Prokaryotes are uni- or multicellular organisms made up of cells that do not have a nuclear envelope (pro-, “before”, karyon,“nucleus”). The genetic material is not bound in a nucleus. They also lack cell organelles such as an endoplasmic reticulum, a Golgi apparatus,lysosomes, and mitochondria. Prokaryotes are divided into two main groups namely the Bacteria and the Archaea (ancient bacteria).

Eukaryotes are multicellular organisms made up of cells (eu-, “true”, karyon, “nucleus”) that possess a membrane-bound nucleus (that holds genetic material) as well as membrane-bound cell organelles. Genetic material in eukaryotes is contained within a nucleus.Eukaryotic organisms include organisms such as plants, animals, fungi, and protists.

Table: Differences between prokaryotes and eukaryotes.