cladisztika

Cladistics, or cladistic analysis (Hungarian: kladisztika), is a method of biological classification that groups organisms into clades—monophyletic groups consisting of an ancestor and all its descendants. The core premise is that evolutionary relationships are best inferred from shared derived characters, or synapomorphies, rather than overall similarity alone, which can be distorted by convergent evolution. Cladograms are branching diagrams that depict hypothesized patterns of descent and common ancestry.

Historically, cladistics was developed by Willi Hennig in the mid-20th century and has since become a dominant framework in systematics. It emphasizes monophyly as the criterion for natural groups and seeks to distinguish true evolutionary lineages from paraphyletic or polyphyletic assemblies. The approach aims to reveal the branching order of organisms rather than reflect rank-based similarity alone.

Methodologically, cladistic analysis combines character data from morphology, molecular sequences, and sometimes behavior. Outgroup comparison is used to polarize character states. Tree-building can rely on maximum parsimony, as well as maximum likelihood and Bayesian inference, with both morphological and molecular data contributing to resolution. The outcome is a cladogram that represents hypothesized relationships among taxa.

Applications include revising classifications, constructing evolutionary trees, and studying character evolution. Cladistics informs taxonomy by focusing on ancestry and shared derived traits rather than traditional ranks, though many classifications still intersect with Linnaean hierarchy. Limitations and debates persist regarding character coding, homoplasy, incomplete lineage sorting, and the computational demands of complex datasets, which continue to shape methodological choices in practice. Numerous clades, such as Vertebrata, Tetrapoda, and Arthropoda, are commonly recovered as monophyletic in cladistic analyses.