Phylogenetic analysis

During the past few decades, phylogenetic analysis has become an important tool throughout biology for comparing information about genes, individuals, populations, and species. This information is usually in the form of morphological, behavioral or molecular data, and phylogenetic analysis is used to estimate the historical relationships among the genes or species, and to depict these relationships in the form of a branching diagram, known as a phylogenetic tree. Beyond the traditional use of phylogeny in evolutionary biology, there has been an increasing realization of the need for phylogenetic analysis in any study in which biological variation is compared across samples. The need for phylogenetic analysis arises from the fact that the objects of study (usually called taxa, whether they are genes, species, or some other level of organization) are not statistically independent, but are connected through historical relationships. Any valid statistical interpretation of the patterns of biological variation among taxa requires an estimate of these historical relationships.