noun, plural: homologies
(1) A degree of similarity, as in position or structure, and that may indicate a common origin; a correspondence of structure
Homology, in general biology, pertains to the degree of similarity, as in position or structure, and that may indicate a common origin.
In genetics, it is associated with the chromosomes and pertains to a condition denoting to the pair of chromosomes having corresponding genes for a particular trait or characteristic. The pair of chromosomes having the same gene sequences, each derived from one parent, is referred to as homologous chromosomes. An example of that would be two chromosomes with genes coding for the eye color: one may code for brown eyes, the other for blue. One of the pair may be dominant and the other is recessive. Hence, even if an individual has genes for brown eyes and blue eyes, only one eye color is expressed.
In evolutionary biology, homology pertains to a state of similarity in structure and anatomical position but not necessarily in function between different organisms. They may arise from a common ancestry or evolutionary origin. An example would be the forelimbs of humans and bats. These structures are described as homologous. These structures have dissimilar function but have the same fundamental skeletal structure and developmental origin. Their similarity in this regard could indicate a likely evolution from a common ancestor.
Word origin: Greek homologia agreement, from homologos agreeing