phylogenetics In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

, informative site is a term used when

maximum parsimony In phylogenetics and computational phylogenetics, maximum parsimony is an optimality criterion under which the phylogenetic tree that minimizes the total number of character-state changes (or minimizes the cost of differentially weighted charact ...

is the

optimality criterion Optimality may refer to: * Mathematical optimization * Optimality theory Optimality theory (frequently abbreviated OT) is a linguistic model proposing that the observed forms of language arise from the optimal satisfaction of conflicting const ...

for construction of a

phylogenetic tree A phylogenetic tree or phylogeny is a graphical representation which shows the evolutionary history between a set of species or taxa during a specific time.Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA. In ...

. It refers to a characteristic for which the number of character-state evolutionary changes of at this site depends on the topology of the tree. The characteristics can take on multiple types of data, including morphological (such as the presence of wings, tentacles, etc.) or molecular information such as sequences of

DNA Deoxyribonucleic acid (; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of al ...

proteins Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, re ...

. The informative site is a position in the relevant set of aligned sequences at which there are at least two different character states and each of those states occurs in at least two of the sequences. In other words, it cannot be a fully conserved (i.e., invariable) site nor can it be a (singleton) site with a difference in only one sequence (as seen, for example, in

single-nucleotide polymorphism In genetics and bioinformatics, a single-nucleotide polymorphism (SNP ; plural SNPs ) is a germline substitution of a single nucleotide at a specific position in the genome. Although certain definitions require the substitution to be present in a ...

s and single-nucleotide variants). In both cases, the number of character-state changes is the same regardless of the topology of the tree, equal to 0 and 1 respectively.

References

Computational phylogenetics {{Bioinformatics-stub