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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 ...
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.
Evidence for common descent comes from the existence of vestigial structures. [72] These rudimentary structures are often homologous to structures that correspond in related or ancestral species. A wide range of structures exist such as mutated and non-functioning genes, parts of a flower, muscles, organs, and even behaviors.
Homologous structures - structures (body parts/anatomy) which are similar in different species because the species have common descent and have evolved, usually divergently, from a shared ancestor. They may or may not perform the same function. An example is the forelimb structure shared by cats and whales.
Pelvic spurs (also known as vestigial legs) are external protrusions found around the cloaca in certain superfamilies of snakes belonging to the greater infraorder Alethinophidia. [1] These spurs are made up of the remnants of the femur bone, which is then covered by a corneal spur, or claw-like structure. [ 1 ]
Convergent evolution is the development of analogous structures that occurs in different species as a result of those two species facing similar environmental pressures and adapting in similar ways. It differs from divergent evolution as the species involved do not descend from a closely related common ancestor and the traits accumulated are ...
That this vestigial response occurs even before becoming consciously aware of a startling noise would explain why the function of ear-perking had evolved in animals. The mechanism serves to give a split-second advantage to a startled animal – possibly an animal being stalked and hunted.
[3] [4] Studies of the genomic organization and of the molecular phylogeny have shown that the nucleomorph of the cryptomonads used to be the nucleus of a red alga, whereas the nucleomorph of the chlorarchniophytes was the nucleus of a green alga. In both groups of organisms the plastids originate from engulfed photoautotrophic eukaryotes.