Vestigiality

In humans the vermiform appendix is a vestigial structure; it has lost much of its ancestral function.

The Darwin-tubercle (left) is a vestigial form of the ear tip (right) in the mammalian ancestors of humans - here shown in a Barbary Ape.

Vestigial hindlegs (spurs) in a Boa constrictor

The blind mole rat (Spalax typhlus) has tiny eyes completely covered by a layer of skin.

Vestigiality refers to genetically determined structures or attributes that have apparently lost most or all of their ancestral function in a given species, but have been retained during the process of evolution. Assessment of the vestigiality must generally rely on comparison with homologous features in related species. The emergence of vestigiality occurs by normal evolutionary processes, typically by loss of function of a feature that is no longer subject to positive selection pressures when it loses its value in a changing environment. The feature may be selected against more urgently when its function becomes definitively harmful. Typical examples of both types occur in the loss of flying capability in island-dwelling species.

单词	Vestigal
释义	Vestigal 英语百科 Vestigiality Vestigiality refers to genetically determined structures or attributes that have apparently lost most or all of their ancestral function in a given species, but have been retained during the process of evolution. Assessment of the vestigiality must generally rely on comparison with homologous features in related species. The emergence of vestigiality occurs by normal evolutionary processes, typically by loss of function of a feature that is no longer subject to positive selection pressures when it loses its value in a changing environment. The feature may be selected against more urgently when its function becomes definitively harmful. Typical examples of both types occur in the loss of flying capability in island-dwelling species.
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Vestigal

Vestigiality