Parafyleettisten

Parafyleettisten, often translated as paraphyletic, is a term used in evolutionary biology and taxonomy to describe a group of organisms that includes a common ancestor but not all of its descendants. This means that a paraphyletic group is defined by the exclusion of certain lineages that have evolved from it. For example, traditional classifications of reptiles are considered paraphyletic because they include the ancestor of birds but exclude birds themselves, even though birds are direct descendants of this reptilian ancestor.

The concept of paraphyly is crucial for understanding phylogenetic relationships. A monophyletic group, in contrast, includes a common ancestor and all of its descendants. Evolutionary biologists strive to define taxonomic groups that are monophyletic, as these groups accurately reflect evolutionary history. The identification of paraphyletic groups often leads to revisions in classification systems to ensure that groups are evolutionarily coherent. Recognizing paraphyly helps scientists understand the patterns of evolution, such as how certain traits have evolved and been lost or modified in different descendant lineages. The term originates from Greek, with "para" meaning "beside" and "phylon" meaning "tribe" or "race," suggesting a group that is beside or separate from a complete evolutionary lineage.