Study of the diversity of life on the planet earth, both past and present, and the relationships among living things through time

Used to understand the evolutionary history of life on earth

Describing, identifying, classifying, and naming of organisms

Systematics is different from taxonomy

A strain is a typical representative of the species to which it may be assigned

Species share a recent common ancestor for their 16S rRNA genes

Species are defined operationally as a group of strains

sharing a high degree of similarity in many traits

A strain is a low-level taxonomic rank used in three related ways, usually at the infraspecific level (within a species)

Only a few characters are considered

More stable classification

Members of different groups are usually not similar in hereditary pattern

Related phylogenetically

The specific name can change if the organism is assigned to another genus because of new information

A law of priority ensures the use of the newest available legitimate name

The generic name is stable

The oldest epithet for a particular organism takes precedence and must be used when you consider the specific name

Photoheterotroph

Chemoautotroph

Photoautotroph

Chemoheterotroph

Grows between -5°C and 15°C, but can grow at temperatures between 45°C and 70°C

Grows between 15°C and 30°C, but can grow at lower temperatures as well

Grows between 25°C and 45°C

Grows between 45°C and 70°C

a

b

c

d

e

The lipid A of Gram negative bacteria like other glyerol lipids contains glycerol to which long-chain hydrocarbons are attached to the hydroxyl groups via carboxylic acid ester linkages

Cell walls of certain methanogens have pseudomurein which replaces NAG with NAT

The glycosidic bonds between the sugar derivatives in archaea is β-1,4 instead of β-1,3

Cell walls of some archaea may be composed of polymers of glucose, glucuronic acid, galactosamine uronic acid, and acetate

Gram positive and Gram negative bacteria produce acidic molecules called teichoic acids embedded in their cell wall

A value of 70% or less genomic hybridization and a difference in SSU rRNA gene sequence of 3% or more between two organisms is taken as evidence that the two are distinct species

The genomic similarity between the two organisms is calculated as a percentage of probe hybridized to target relative to a control (probe DNA hybridized to target DNA from the same organism)

Pairs of strains that share greater than 70% 16S rRNA gene sequence similarity and 97% genomic hybridization values are likely members of the same species

The degree of DNA–DNA hybridization between the genomes of two organisms provides a measure of their genomic similarity