Speciation and classification

Classification is a means of organising the variety of life based on relationships between organisms and is built around the concept of species. Two organisms belong to the same species if they are able to produce fertile offspring. The fact that all organisms share a common ancestry allows them to be classified.

Originally classification systems were based only on observable features but more recent approaches draw on a wider range of evidence to clarify relationships between organisms. This has been helped by advances in genetic technology.

A phylogenetic classification system attempts to arrange species into groups based on their evolutionary origins and relationships. It uses a hierarchy in which smaller groups are placed within larger groups, with no overlap between groups. Each group is called a taxon (plural taxa). One hierarchy comprises the taxa: domain, kingdom, phylum, class, order, family, genus and species. Each species is universally identified by a binomial consisting of the name of its genus and species, eg Homo sapiens.

Transfer of genetic information from one generation to the next can either ensure continuity of the species or lead to variation within a species, which can ultimately lead to the formation of a new species.

Factors such as reproductive isolation can lead to accumulation of different genetic information in populations', potentially leading to the formation of new species.

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