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Two individuals have a genetic relationship if one is the ancestor of the other or if they share a common ancestor. In evolutionary theory, species which share an evolutionary ancestor are said to be of common descent. However, this concept of ancestry does not apply to some bacteria and other organisms capable of horizontal gene transfer. Some ...
Common descent is a concept in evolutionary biology applicable when one species is the ancestor of two or more species later in time. According to modern evolutionary biology, all living beings could be descendants of a unique ancestor commonly referred to as the last universal common ancestor (LUCA) of all life on Earth. [1] [2] [3] [4]
Also called the last universal cellular ancestor or simply the last universal ancestor. The most recent population of organisms from which all extant organisms on Earth share a common descent; i.e. the most recent common ancestor of all organisms now living. LUCA is not thought to have been the earliest life on Earth, but rather the only ...
A proposed, earlier, non-cellular ancestor to LUCA is the First universal common ancestor (FUCA). [71] [72] FUCA would therefore be the ancestor to every modern cell as well as ancient, now-extinct cellular lineages not descendant of LUCA. FUCA is assumed to have had other descendants than LUCA, none of which have modern descendants.
Sequence comparison is considered a measure robust enough to correct erroneous assumptions in the phylogenetic tree in instances where other evidence is scarce. For example, neutral human DNA sequences are approximately 1.2% divergent (based on substitutions) from those of their nearest genetic relative, the chimpanzee , 1.6% from gorillas ...
The blue and orange subgroups are clades; each shows its common ancestor stem at the bottom of the subgroup branch. The green subgroup alone does not count as a clade; it is a paraphyletic group with respect to the blue group, because it excludes the blue branch which has descended from the same common ancestor. The green and blue subgroups ...
The tree of life or universal tree of life is a metaphor, conceptual model, and research tool used to explore the evolution of life and describe the relationships between organisms, both living and extinct, as described in a famous passage in Charles Darwin's On the Origin of Species (1859).
Willi Hennig 1972 Peter Chalmers Mitchell in 1920 Robert John Tillyard. The original methods used in cladistic analysis and the school of taxonomy derived from the work of the German entomologist Willi Hennig, who referred to it as phylogenetic systematics (also the title of his 1966 book); but the terms "cladistics" and "clade" were popularized by other researchers.