Page 3 - LN

 The flippers are used for swimming, the forelimbs of frogs are used for jumping
and propping, and the forelimbs of man are used for writing, eating, holding
things, etc.

→ Homologous organs provides evidence for evolution by telling us that they are
derived from the same ancestor.

Analogous Organs
 Analogous organs are defined as the organs of different animals that are having
different structure but perform the same functions.

 Example of analogous organ is the wings of insect and the wings of the bird. The
structure of wings of the bird has bones covered by flesh, skin, and feathers.
Whereas the wings of insect is an extension of integument. But in both the cases
the wings are used for flying.

 These organisms would have to adapt to the same ecological niche as other
organisms.

 Hence, they may have evolved similar (analogous) organs. Analogous organs
provide mechanism for evolution.

Difference between Homologous and Analogous organs

Homologous Structure Analogous Structure

Similar anatomy Dissimilar anatomy

Dissimilar functions Similar Functions

Inherited from a common ancestor Not inherited from ancestors

Develops in related species Develops in unrelated species

A result of divergent evolution A result of convergent evolution

Developed as a result of the adaptation Developed as a result of the adaptation to a
to a different environment similar environment

An arm of a human, the leg of a dog or a From wings in birds, bats and insects to fins in
flipper of a whale are all homologous penguins and fishes are all analogous structures
structures

3