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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]
Monophyletic phylogenetic tree of organisms". [23] Phylogenetic nomenclature is a semantic extension of the general acceptance of the idea of branching during the course of evolution, represented in the diagrams of Jean-Baptiste Lamarck and later writers like Charles Darwin and Ernst Haeckel.
A rooted tree of life into three ancient monophyletic lineages: bacteria, archaea, and eukaryotes based on rRNA genes Lineages are typically visualized as subsets of a phylogenetic tree . A lineage is a single line of descent or linear chain within the tree, while a clade is a (usually branched) monophyletic group, containing a single ancestor ...
The two approaches, evolutionary taxonomy and the phylogenetic systematics derived from Willi Hennig, differ in the use of the word "monophyletic". For evolutionary systematicists, "monophyletic" means only that a group is derived from a single common ancestor.
These relationships are determined by phylogenetic inference methods that focus on observed heritable traits, such as DNA sequences, protein amino acid sequences, or morphology. The result of such an analysis is a phylogenetic tree—a diagram containing a hypothesis of relationships that reflects the evolutionary history of a group of ...
It is now known that Orchidaceae is the most basal clade in Asparagales, with the astelioid clade diverging next. [16] [17] According to cladistic analyses based on morphological character states or on nucleotide sequences, the orchid family is a monophyletic group. The subfamilies recognized by Dressler, however, were not all monophyletic.
Recent studies, as per the APG, show that the monocots form a monophyletic group (a clade), but that the dicots are paraphyletic; nevertheless, the majority of dicot species fall into a clade with the eudicots (or tricolpates), with most of the remaining going into another major clade with the magnoliids (containing about 9,000 species).