Species
From BioMineWiki
Generally, a class of individuals with common qualities and a common name. But there is also a specific biological meaning with the species classification. A species in biology is a category of biological classification ranking below the genus.
During the era before genetic information morphological changes where used to define a species. Therefore a plant or animal species was defined to be:
- A population of individuals able to interbreed under natural conditions
- Able to produce fertile offspring
- Reproductively isolated from other populations
Species concept of prokaryotes
The older (above mentioned) classification is not relevant for prokaryotes because they
- Reproduce asexually by binary fission and produce clones
- May transfer genetic variation within and between species by horizontal gene transfer
- Have a high frequency of heterologous recombination, which allows the acquisition of genetic material which was not present in the original species.
{Guerrero, 2002 #47}
Current patterns of biodiversity are the results of past events reflected in the genetic code. Therefore prokaryotes and eukaryotes are classified as species on genetic bases:
- Homologous genetic sequences (“molecular clocks”) are compared. Classification is based on the number of amino acid substitutions between the sequences.
- A new prokaryote species is defined to have a 16S ribosomal RNA sequence that differs more than 3% from all other organisms.
In addition to the species concept, microbes are usually also classified according to the kind of environment where they thrive.
Naming
A species is a category of biological classification ranking below the genus. Therefore a species is designated by a binomial that consists of the name of the genus followed by a Latin or latinized uncapitalized noun or adjective agreeing grammatically with the genus name, for example Acidithiobacillus ferrooxidans.
