Homology: Homology is the reonship among organs of different groups of organisms, that show similarity in their basic structure and embryonic development, but perform different functions.
Homology of organs of different organisms indicates their common ancestry.
Homology is found in the bones of forelimbs of whales, cheetah, birds, amphibians and humans, they have similar basic anatomical structure with the bones humerus, radius,ulna,carpals, metacarpals and phalanges.
Other examples are the hearts and brains of vertebrates.
Among plants, the thorns of Bougainvillea and tendrils of Cucurbita represent homology.
Homology or homologous organs is/are the result of divergent evolutions, i.e., the evolutionary process where the same structure develops along different directions due to adaptations for different needs.
(ii) Analogy : Analogy is the relationship among organs of different groups of organisms performing the same function, irrespective of structural of anatomical differences.
Some examples of organs showing analogy are:
• Eyes of octopus and those of mammals.
• Wings of a butterfly (insect) and those of birds.
• Flippers of whales or dolphins and those of penguins.
Tubers of sweet potato (root modified) and those of potato (stern modified).
Analogy is the result of convergent evolution, i.e., the evolutionary process, where anatomically different structures in different groups of organisms evolve towards the same function. It is the similar habitat conditions that have selected similar adaptive features in different groups of organisms, towards the same function,
