Distinguish between homologous and analogous organs.
Hint: Between homologous and analogous organs, one type originates from a similar embryonic source, while analogous organs share a common function. Some organisms can be very closely related genetically, yet small genetic differences can cause significant changes in their appearance, making them look quite distinct.
Complete answer:
Traits in organisms are often classified as either homologous or analogous. Homologous structures have the same embryonic origin, while analogous organs serve the same purpose. For example, the bones in a whale’s front flipper are homologous to those in a human arm, meaning they share a common origin but not the same function, so they are not analogous. In contrast, the wings of a butterfly and a bird perform similar functions, making them analogous, though they do not share a common origin. Some features can be both homologous and analogous, such as the wings of a bird and a bat, which share both structure and function.
|
Homologous Structure |
Analogous Structure |
| Exhibit similar anatomical structures | Exhibit different anatomical structures |
| Perform different functions | Perform similar functions |
| Inherited from a common ancestor | Not inherited from a common ancestor |
| Found in closely related species | Found in unrelated species |
| Result from divergent evolution | Result from convergent evolution |
| Develop as adaptations to varied environments | Develop as adaptations to similar environments |
| Examples: human arm, dog leg, whale flipper, and fish fin | Examples: wings of birds, bats, and insects, as well as fins of penguins and fish |
Note:
Some organisms may be closely related yet show significant differences in appearance due to minor genetic changes that result in major morphological differences. Conversely, distantly related organisms can appear quite similar because they have developed similar adaptations in response to comparable environmental conditions.