Kladistika

Kladistika is a method of classifying organisms into groups called clades, which are based on shared derived characteristics. These characteristics, known as synapomorphies, are inherited from a common ancestor and distinguish a clade from other groups. The goal of cladistics is to reconstruct the evolutionary history of life by identifying these nested relationships. A clade must include an ancestral species and all of its descendants. Cladistic analysis typically involves creating a data matrix of traits for different species and then using algorithms to determine the most likely phylogenetic tree that explains the observed distribution of these traits. This tree, also known as a cladogram, visually represents the evolutionary relationships. Strictly speaking, only monophyletic groups, which are clades, are considered valid in cladistics. Paraphyletic groups (which exclude some descendants of a common ancestor) and polyphyletic groups (which include organisms from different lineages) are not recognized as natural evolutionary units. Cladistics has become a dominant approach in systematics, influencing fields such as evolutionary biology, paleontology, and molecular phylogenetics.