5.3 Classification and Biodiversity

5.3 Syllabus

U1. The binomial system of names for species is universal among biologists and has been agreed and developed at a series of congresses.

-The binomial system of nomenclature is the formal system by which all living species are classified (taxonomy). It was initially developed by a Swedish botanist named Carlous Linnaeus in 1735.

-The binomial system of nomenclature provides value because:

It allows for the identification and comparison of organisms based on recognized characteristics
It allows all organisms to be named according to a globally recognized scheme
It can show how closely related organisms are, allowing for the prediction of evolutionary links

U2. When species are discovered they are given scientific names using the binomial system.

-A formal two naming system of classifying species. The first name in the binomial naming system is called the genus and is always capitallized. The second name starts with a small letter and is called the species

-The binomial system allows for scientists across cultures, regions and languages to communicate effectively with regards to specific organisms.
-Species= the natural basic grouping of organisms

A group of organisms with similar characteristics
Which can interbreed
and produce fertile offspring

-Genus= every species is classified into a genus

A group of similar species

-Binomial nomenclature

First name= Genus written in italics, if in type, or underlined if not, with the first letter in upper case
Second name = Species, written in italics, if in type, or underlined if not, all letters in lower case

U3. Taxonomists classify species using a hierarchy of taxa.

-Taxonomy is the science involved with classifying groups of organisms on the basis of shared characteristics. Organisms are grouped according to a series of hierarchical taxa - the more taxa organisms share, the more similar they are.

-The taxa used are kingdom, phylum, class, order, family, genus and species

A taxon means a group of something
Scientists arrange or organize species in to a hierarchical set of groups in order to organize organisms into specific similar groups based on similar characteristics
As one goes higher up on a classification chart, the greater the number of species are included into the group

U4. All organisms are classified into three domains.

-Currently, all living organisms are classified into three domains. Archaea, eubacteria and eukaryote should be used for three domains.

Eukarya- Eukaryotic organisms that contain a membrane-bound nucleus (includes protist, plants, fungi and animals)
Archaea- Prokaryotic cells lacking a nucleus and consist of the extremophiles (e.g. methanogens, thermophiles, etc.)
Eubacteria- Prokaryotic cells lacking a nucleus and consist of common pathogenic forms (e.g. E. coli)

-Members of these domains should be referred to as archaeans, bacteria and eukaryotes.

The Archaea and Bacteria domains are prokaryotes. These are organisms that do not have a membrane bound nucleus and their DNA is not associated with proteins.
The Bacteria domain consists of Eubacteria and archaebacteria are classified as Archaeans.
The Eukarya domain includes eukaryotes, or organisms that have a membrane bound nucleus. This domain is further subdivided into the kingdoms Protista, Fungi, Plantae and Animalia
Groups organisms primarily based on differences in ribosomal RNA structure. Ribosomal RNA is a molecular building block for ribosomes.

U6. In a natural classification, the genus and accompanying higher taxa consist of all the species that have evolved from one common ancestral species.

-For natural classification, it is assumed that all members of that group shared a common ancestor at some point in their history. This can be seen in their structure. Unnatural or artificial classification for example would be birds and flies. They both can fly; however flight evolved separately, and they are classified separately.

U7. Taxonomists sometimes reclassify groups of species when new evidence shows that a previous taxon contains species that have evolved from different ancestral species.

-Sometimes new evidence is found that shows scientists that members of a particular group do not share a common ancestors as once originally thought. Sometimes other species that were once thought to be a lot different, are found to be more similar; sharing a common ancestor. The switching of classification is an ongoing process as new discoveries or better methods of classification are found.

U8. Natural classification helps in identification of species and allows the prediction of characteristics shared by species within a group.

-Historically, there have been two main classification schemes used to identify living organisms - artificial and natural classification. Both use prominent features as the basis for classification, however differ in the way these characteristics are established

Artificial classification involves arbitrarily selecting unifying characteristics first and then grouping organisms accordingly
Natural classification involves grouping organisms based on similarities first and then identifying shared characteristics. A third type of classification - phylogenetic classification - is now being used to differentiate organisms based on genetics

-Natural classification is very useful for research into biodiversity. It is easier in identification of new species that do not obviously fit into a specific classification.