Definitions of Species
- Scientists have been classifying organisms into species for hundreds of years, in order to investigate the diversity of life that exists today and in the past
- There is difficulty in determining whether new organisms discovered belong to an existing species, or a new one
- This is because the most widely accepted definition of a species is:
- A group of organisms with similar morphological and physiological features that able to breed together and produce fertile offspring
- This is the biological species concept, and is reliant on determining whether interbreeding produces fertile offspring - this is difficult and time-consuming to determine in practice
- However there are other discriminating factors that scientists can use to group similar organisms together
Morphological species concept
- In the past, most scientists described organisms by their physical features (morphology) as these can be more easily observed
- They group together organisms that share many physical features that distinguish them from other species
- This is the morphological species concept
Ecological species concept
- When there is a population of similar organisms living in the same area at the same time, they can be described as an ecological species
- This is the ecological species concept
Naming species
- Species are often given common names, but in order to avoid confusion about what group of organisms scientists are talking about, all species are given a two-part scientific name using the binomial system
- This naming convention was developed and established by the Swedish scientist Carl Linnaeus in the 18th Century
- The first part of the name is the genus that the species belongs to; this is a group of very similar organisms
- The second part of the name is specific and unique to a single group of organisms that are identified as a species (and occasionally there may be a third name)
- The binomial name is always italicized in writing (or underlined if it is not possible to italicise)
- For example:
- The most commonly known yeast is Saccharomyces cerevisiae
- It is common to abbreviate the genus name: S. cerevisiae
- Saccharomyces paradoxus is another species of that is a member of the same genus as cerevisiae
