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The term monophyly, or monophyletic, derives from the two Ancient Greek words μόνος (mónos), meaning "alone, only, unique", and φῦλον (phûlon), meaning "genus, species", [4] [5] and refers to the fact that a monophyletic group includes organisms (e.g., genera, species) consisting of all the descendants of a unique common ancestor.
In biological phylogenetics, a clade (from Ancient Greek κλάδος (kládos) 'branch'), also known as a monophyletic group or natural group, [1] is a grouping of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. [2]
They held that only monophyletic groups should be accepted as formal ranks in a classification and that – while this approach had been impractical previously (necessitating "literally dozens of eukaryotic 'kingdoms '") – it had now become possible to divide the eukaryotes into "just a few major groups that are probably all monophyletic". [42]
Cladistics (/ k l ə ˈ d ɪ s t ɪ k s / klə-DIST-iks; from Ancient Greek κλάδος kládos 'branch') [1] is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry.
Many cladistic systems therefore redefine Reptilia as a clade (monophyletic group) including birds, though the precise definition of this clade varies between authors. [4] [3] Others prioritize the clade Sauropsida, which typically refers to all amniotes more closely related to modern reptiles than to mammals. [4]
In biology, taxonomic rank (which some authors prefer to call nomenclatural rank [1] because ranking is part of nomenclature rather than taxonomy proper, according to some definitions of these terms) is the relative or absolute level of a group of organisms (a taxon) in a hierarchy that reflects evolutionary relationships.
A taxon is called monophyletic if it includes all the descendants of an ancestral form. [61] [62] Groups that have descendant groups removed from them are termed paraphyletic, [61] while groups representing more than one branch from the tree of life are called polyphyletic.
"Tricolpate" is a synonym for the "Eudicot" monophyletic group, the "true dicotyledons" (which are distinguished from all other flowering plants by their tricolpate pollen structure). The number of pollen grain furrows or pores helps classify the flowering plants, with eudicots having three colpi (tricolpate), and other groups having one sulcus ...