the quality of being homologous; morphological or other similarity of structures.

Homologs have common origins but may or may not have common activity. Genes that share an arbitrary threshold level of similarity determined by alignment of matching bases are termed homologous. They are inherited from a common ancestor which possessed the structure. This may be difficult to determine when the structure has been modified through descent. Note: homology is a qualitative term (something is either homologous or not), while similarity is the corresponding quantitative term. Therefore, it is more appropriate to refer to xx % similarity (i.e. never xx % homology).

(i) Sequence identity between two nucleotide sequences. (ii) Genetic relatedness between two sequences of common ancestry. Commonly confused with sequence similarity. For example, 85% similarity means that 85 nucleotide positions out of 100 are identical in the two polynucleotides.

Similarity by common ancestry or genetic relatedness.

a similar character state present in two or more species of organisms, and derived from a single character in their common ancestor. (homologous, adj.)

Refers to two genes, from different organisms and therefore of different sequence, that code for the same gene product. Two homologous genes ate usually sufficiently similar in sequence for one to be used as a hybridization probe for the other.

Similarity in structure of an organ or a molecule, reflecting a common evolutionary origin. Specifically, such a similarity in protein or nucleic acid sequence. Contrasted with analogy - a similarity that does not reflect a common evolutionary origin.

Degree of identity existing between the nucleotide sequences of two related but not complementary DNA or RNA molecules; 70 % homology means that on the average 70 out of every 100 nucleotides are identical in a given sequence. The same term is used in comparing the amino acid sequences of related proteins.

(strict) Two or more biological species, systems or molecules that share a common evolutionary ancestor. (general) Two or more gene or protein sequences that share a significant degree of similarity, typically measured by the amount of identity (in the case of DNA), or conservative replacements (in the case of protein), that they register along their lengths. Sequence "homology" searches are typically performed with a query DNA or protein sequence to identify known genes or gene products that share significant similarity and hence might inform on the ancestry, heritage and possible function of the query gene.

This is a gene, gene product or compound that shares a common ancestry or morphology with a different gene, gene product or compound.

The degree to which two pieces of DNA match, or complement each other (two pieces of DNA are complementary if their respective nucleotides, in their current order, match C to G and A to T). If one piece of DNA is 100% complementary to another piece of DNA, they demonstrate very high homology; if the pieces are only able to form a handful of base pairs between their corresponding nucleotides, they demonstrate very low homology.

Common ancestry of two or more genes or gene products.

Quality of being homologous and therefore corresponding in structure, position, or origin.

a similarity due to inheritance from a common ancestor.

Similarity of characters derived from a common ancestral origin.

Similarity attributed to descent from a common ancestor.

Homology refers to elements of a protein's amino acid sequence that when compared to other proteins, are similar. Homologous proteins share similar ancestry, and may be functionally related. See also Conservation, Domain, Orthology, Paralogy.

Being related by the evolutionary process of divergence from a common ancestor. Homology implies similarity, but low similarity does not necessarily prove homology. See also: Twilight zone, Midnight zone

Resemblance in characteristics (e.g., body form, behavior) as a consequence of common ancestry, also see Analogy

Similarity of the structure, physiology, or development of different species of organisms based upon their descent fro a common evolution ancestor

the quality of being similar or corresponding in position or value or structure or function

a characteristic which is similar if not identical as a consequence of common evolutionary descent

a character shared between species that was also present in their common ancestor

a structural similarity among organisms

A similarity of structures due to their 'affinity' through an ideal type, or archetype, according to Richard Owen. In modern evolutionary theory, the similarity is homologous if it evolved from the same structure in a common ancestor. Otherwise, any similarity is convergent and therefore 'analogous'. See also transcendentalism.

The degree of identity between individuals, or characters. The degree of identity between the nucleotide sequences of two nucleic acid molecules or the amino acid sequences of two protein molecules. Although sequence determination is the ultimate test of homology, useful estimates can be provided by either DNA-DNA or DNA-RNA hybridization.

Similarity in characteristics resulting from a shared ancestry.

Being related by the evolutionary process of divergence from a common ancestor. Homology is not a synonym for similarity.

Evolutionary descent from a common ancestor due to gene duplication.

Similarity due to common ancestry.

similarity or correspondence. Homologous DNA is similar at matched positions (e.g., SIV and HIV-2 are 70% homologous). Homologous blood or tissue transfers are those which are transferred or transplanted from one individual to another. Contrast with autologous. (adjective homologous)

similarity in the sequence of a protein or nucleic acid or in the structure of an organ that reflects a common evolutionary origin. Molecules or sequences that exhibit homology are referred to as homologs. In contrast, analogy is a similarity in structure or function that does not reflect a common evolutionary origin.

(adj. homologous) Similarity due to common evolutionary origin, i.e. derived from the same ancestral character; thus, equivalent to synapomorphy. Morphologists also define homology by common developmental origin, which is quite a different concept, being based on a different process, although empirically the two homologies may be congruent. Non-cladists like to include symplesiomorphy in their concept of homology.

Here, a relationship of having evolved from the same ancestral gene. Two nucleic acids are said to be homologous if their nucleotide sequences are identical or closely related. Similarly, two proteins are homologous if their amino acid sequences are related. Homology can also be inferred from structural similarity.

similarity in nucleotide or protein sequence between two individuals within the same species, or among different species.

Similarity in DNA or protein sequences between individuals of the same species or among different species.

Refers to similar structures, regardless of function. For evolutionists, structures are homologous only if they were derived from the same structure in a common ancestor.

That relation between parts which results from their development from corresponding embryonic parts, either in different animals, as in the case of the arm of man, the fore-leg of a quadruped, and the wing of a bird; or in the same individual, as in the case of the fore and hind legs in quadrupeds, and the segments or rings and their appendages of which the body of a worm, a centipede, &c., is composed. The latter is called serial homology. The parts which stand in such a relation to each other are said to be homologous, and one such part or organ is called the homologue of the other. In different plants the parts of the flower are homologous, and in general these parts are regarded as homologous with leaves. 93

Two structures are considered homologous when they are inherited from a common ancestor which possessed the structure. This may be difficult to determine when the structure has been modified through descent.

structural similarity due to descent from a common ancestor or form.

similarity of features based on common descent.

Homology is the similarity of characters found in different species that are due to common descent. Examples include the flippers of whales and our arms.

In biology, homology is any similarity between structures that is due to their shared ancestry. There are examples in different branches of biology. Anatomical structures that perform the same function in different biological species and evolved from the same structure in some ancestor species are homologous.

In mathematics (especially algebraic topology and abstract algebra), homology (in Greek homos = identical) is a certain general procedure to associate a sequence of abelian groups or modules with a given mathematical object such as a topological space (singular homology) or a group. See homology theory for more background.

In anthropology and archaeology, homology is a type of analogy whereby two human beliefs, practices or artefacts are separated by time but share similarities due to genetic or historical connections. Specifically in anthropology, a homology is a structure that is shared through descent from a common ancestor.

Homologies are a "structural 'resonances'...between the different elements making up a socio-cultural whole."