What is the difference between homologous and analogous structures?
The evolution of organisms has resulted in the development of homologous and analogous structures in different species. These structures happen to be the reason behind divergent and convergent evolution.
The main difference between homologous and analogous structures is that the former are developed from a common ancestor while the latter belong to unrelated species in spite of having similar functions.
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Comparison Table (Homologous vs Analogous Structures)
| Basic Terms | Homologous Structures | Analogous Structures |
| Meaning | These are structures that have evolved from living organisms with the same ancestry. | These are structures that have evolved independently from different organisms but serve the same function |
| Examples | Wings of bats, bird, arms of humans, legs of dogs, and fins of whales | Wings in birds, bats, and fins of fishes |
| Anatomy | Similar anatomy | Dissimilar anatomy |
| Functions | Dissimilar functions | Similar functions |
| Development | From structures of related species | Developed from structures of unrelated species |
| Type of Evolution | Divergent | Convergent |
| Other Features | Develop due to adaptation to the different environment | Develop due to adaptation to the same environment |
What Are Homologous Structures?
Homologous structures are anatomical structures that evolved from organisms having the same ancestry. These structures develop from organisms of related species but they do perform different functions.
Homologous structures result in divergent evolution. It is an evolution where related species adapt to a specific environment due to the natural selection process.
Natural selection processes occur due to migration, mutation, variations, and competition with other related species. The homologous structures usually occur in both plants and animals.
Common examples of homologous structures in plants are leaves of oak and spines of cactus. These structures are quite different but both the spines and leaves perform the same function.
Common examples of homologous structures in animals are the tail of dogs, cats, and the tailbone of human beings. The tails of animals are intact while that of humans have become vestigial structures.
What Are Analogous Structures?
Analogous structures are morphological structures that evolved independently from different organisms to perform the same function.
Analogous structures result in the development of convergent evolution. It helps to highlight how unrelated species adapt to the environment and cope up with the situation.
Common examples of analogous structures in the animal kingdom are the wings of birds, flying insects, and bats. These structures occur from unrelated organisms but perform the same function.
Common examples of analogous structures in the plant kingdom are succulent leaves of cactus and African euphorbias. These structures are responsible for the storage of water.
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Main Difference between Homologous and Analogous Structures
- Homologous structures have similar anatomy while analogous structures have dissimilar anatomy.
- Homologous structures have dissimilar functions while analogous structures have similar functions.
- Homologous structures are inherited from a common ancestor whereas analogous structures are not inherited from a common ancestor
- Homologous structures occur in related species while analogous structures develop in unrelated species
- Homologous structures result in divergent evolution while analogous structures result in convergent evolution
- Homologous structures develop to adapt in different environments while analogous structures develop to adapt in a specific environment.
- Examples of homologous structures are human arms and legs of dogs while analogous structures are wings of birds, bat, and flying insects.
Similarities between Homologous and Analogous Structures
- Occur both in plant and animal kingdom
- Both result in a certain type of evolution
- Both help the organism to adapt to the environment
Comparison Video
Summary
Homologous and analogous structures are terms used in the study of evolution. These two crucial terms tend to confuse many students pursuing biological sciences.
These structures help learners to understand the variations and similarities of living organisms. Organisms with homologous structures have common ancestry while those with analogous structures are different.
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