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Such vestigial structures typically are degenerate, atrophied, or rudimentary, [3] and tend to be much more variable than homologous non-vestigial parts. Although structures commonly regarded "vestigial" may have lost some or all of the functional roles that they had played in ancestral organisms, such structures may retain lesser functions or ...
Vestigial structures and comparisons in embryonic development are largely a contributing factor in anatomical resemblance in concordance with common descent. Since metabolic processes do not leave fossils, research into the evolution of the basic cellular processes is done largely by comparison of existing organisms' physiology and biochemistry .
Arrows show the vestigial structure called Darwin's tubercle. In the context of human evolution, vestigiality involves those traits occurring in humans that have lost all or most of their original function through evolution. Although structures called vestigial often appear functionless, they may retain lesser functions or develop minor new ones.
Homology includes a unique group of shared structures referred to as vestigial structures. Vestigial refers to anatomical parts that are of minimal, if any, value to the organism that possesses them. These apparently illogical structures are remnants of organs that played an important role in ancestral forms.
As of 2007, only two monophyletic groups of organisms are known to contain plastids with a vestigial nucleus or nucleomorph: the cryptomonads [3] of the supergroup Cryptista and the chlorarachniophytes [4] of the supergroup Rhizaria, both of which have examples of sequenced nucleomorph genomes.
During evolution, some structures may lose their original function and become vestigial structures. [171] Such structures may have little or no function in a current species, yet have a clear function in ancestral species, or other closely related species.
However, because evolution is a branching process that produces a complex bush pattern of related species rather than a linear process producing a ladder-like progression, and because of the incompleteness of the fossil record, it is unlikely that any particular form represented in the fossil record is a direct ancestor of any other. Cladistics ...
The repeated independent evolution of nylonase in two different strains of Flavobacterium and one strain of Pseudomonas. The myoglobin from the abalone Sulculus diversicolor has a different structure from normal myoglobin but serves a similar function — binding oxygen reversibly. "The molecular weight of Sulculus myoglobin is 41kD, 2.5 times ...