Paraphyletikus

Paraphyletikus is the Hungarian term for paraphyletic, a concept in phylogenetics and taxonomy. A paraphyletic group includes the most recent common ancestor of the group and some, but not all, of its descendants. In other words, it contains an ancestral lineage but omits one or more lineages that descend from that same ancestor.

Paraphyly is distinguished from two related concepts. A monophyletic group, or clade, includes the ancestor and all of its descendants. A polyphyletic group gathers organisms without including the most recent common ancestor of all members, often grouping together lineages based on convergent traits rather than shared ancestry. Paraphyletic groups often arise from traditional classifications that relied on visible features (plesiomorphies) rather than on derived, shared traits (synapomorphies).

Common examples are historical plant and animal groups where later-diverging lineages are excluded. A classic oft-cited example is Reptilia when birds are excluded: reptiles share a common ancestor with birds and other descendants, but the group as traditionally defined omits birds, rendering it paraphyletic.

In modern systematics, monophyly is generally preferred for formal taxonomy because it best reflects evolutionary history. Paraphyletic groups may still appear in descriptive or historical contexts and can be useful for illustrating evolutionary relationships without reclassifying all descendants. Understanding paraphyly helps clarify how classifications change as new phylogenetic data reveal the full pattern of descent.