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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 and all its descendants. [3] Phylogenetic trees are typically created from DNA, RNA or protein sequence data. Apart from this, morphological differences and similarities have been, and ...
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.
A clade is by definition monophyletic, meaning that it contains one ancestor which can be an organism, a population, or a species and all its descendants. [ note 1 ] [ 10 ] [ 11 ] The ancestor can be known or unknown; any and all members of a clade can be extant or extinct.
Also called a monophyletic group. A phylogenetic grouping of organisms that consists of a single common ancestor and all of its lineal descendants , and which by definition is monophyletic . The common ancestor may be an individual organism, a population , a species , or any other taxon ; any and all members of a clade may be extant or extinct .
In mathematics and science, a nonlinear system (or a non-linear system) is a system in which the change of the output is not proportional to the change of the input. [1] [2] Nonlinear problems are of interest to engineers, biologists, [3] [4] [5] physicists, [6] [7] mathematicians, and many other scientists since most systems are inherently nonlinear in nature. [8]
Homology is the term used to characterize the similarity of features that can be parsimoniously explained by common ancestry. Homoplasy is the term used to describe a feature that has been gained or lost independently in separate lineages over the course of evolution.
Molecular systematics is an essentially cladistic approach: it assumes that classification must correspond to phylogenetic descent, and that all valid taxa must be monophyletic. This is a limitation when attempting to determine the optimal tree(s), which often involves bisecting and reconnecting portions of the phylogenetic tree(s).
The idea of a tree of life arose from ancient notions of a ladder-like progression from lower into higher forms of life (such as in the Great Chain of Being).Early representations of "branching" phylogenetic trees include a "paleontological chart" showing the geological relationships among plants and animals in the book Elementary Geology, by Edward Hitchcock (first edition: 1840).