Q.(a) Differentiate between analogous and homologous structures.

Homologous and Analogous Organs

Comparative anatomy provides evidence for evolution through two contrasting kinds of structures.

Homologous organs have the same fundamental structure and developmental origin but may perform different functions. They arise by divergent evolution from a common ancestor (adaptive radiation). Examples: the forelimbs of humans, whales, bats and cheetahs; and, in plants, the thorn of Bougainvillea and the tendril of Cucurbita — both modified axillary buds with a common origin but different functions.

Analogous organs have different structure and origin but perform the same function; they result from convergent evolution in unrelated lineages facing similar environments. Examples: the wings of insects and birds; the eyes of octopus and mammals; the flippers of penguins and dolphins. …