The counterpart structures are structures that do not show exact similarity in appearance and function, but are linked to their common ancestor. On the other hand, the analogous structures are those structures that are similar in function and appearance but have no link between their ancestors.
The arms of humans, the legs of dogs, are common examples of homologous structure, where they must have diverged and evolved as different beings. The wing of insects, birds, bats and penguin flippers are the common examples of analogous structure, as they do not show any typical ancestral appearance, but their structures exhibit similar action.
Understanding the structural similarity and diversity of organisms helps researchers to gain accurate knowledge of those organisms, and also helps them to understand their nature so that they can learn about the human biological process. It can also guide them in the production of medicines and for better treatment of humans and other related animals. It will also reduce the risk of experimenting with any kind of dangerous treatment directly for humans.
Thinking about nature and its variation within different organisms is amazing and then looking closely at how we all evolved from a single cell to multicellularity and living with all kinds, from the smallest like insects to the giant like the whale is in itself a great work of research that is still going on.
But with changes in the environment, all living things evolved and we have shown tremendous morphological change with time upward, compared to the ancestors. Like before, we all had tails, including humans, but now we don’t have tails, giraffes didn’t have long necks, but now they are the tallest of all, and so on.
However, in this article, we will study the differences between the two terms homologous and analogous structure, which are advantageous for recognising diversity.
Comparative chart
| BASIS FOR COMPARISON | COUNTERPART STRUCTURES | ANALOGOUS STRUCTURES |
|---|---|---|
| Sense | A similar structure that is present in related organisms or common ancestors is known as homologous structures. | A similar structure that is present in unrelated organisms or organisms that do not share a common ancestor but have a similar function are known as analogue structures. |
| Example | The wings of a bat, the wings of birds, the arm of humans, the leg of dogs and the fin of a whale (these are mammals, but the function of the structures is different). | The wings of insects, bats, birds, and the fins of fish and penguins are analogous structures. |
| Anatomy | Shows a similar anatomy. | Show different anatomy. |
| Functions | They are different in function. | They are similar in their functions. |
| is developed | Such structures develop in a species related. | Such structures develop in unrelated species. |
| Other features | The homologous structure is inherited from the ancestors. | Analogous structure is not inherited from its ancestors. |
| The homologous structure arises from the divergent evolution. | The analogous structure arises from convergent evolution. | |
| The homologous structure developed due to adaptation to the different environment. | Analogous structure developed due to adaptation to a similar environment. |
Definition of homologous structures
One of the essential terms for understanding the anatomical structure is the homologywhich refers to a structure that arises from common ancestors or is closely related, but the structure differs in function. These organisms are said to have undergone divergent evolution.
When closely related species evolve and become less similar in function and structure, this is referred to as divergent species. Occurs when such species adapt to the particular environment as part of the process of natural selection. This may be due to migration to new locations, competition with other species, or other microevolutionary changes such as mutations, variations, etc.
The typical example are the tails of dogs, cats and the coccyx of humans. Just as over time, the human coccyx or tailbone has become vestigial organs, but animals such as dogs and cats still have an intact tail.
Even plants, such as the leaves of the oak tree and the spines of the cactus, look different from each other, but they also represent homology. Like the leaf of the oak tree works in the process of photosynthesis and cactus spines prevent water loss from plants and also play an important role in photosynthesis.
Definition of analogous structures
Analogue structures or analogy is the term that says that there are no common ancestors of the two organisms; but also their anatomical structure performs the same functions and even resemble each other. As indicated above also, such organisms have no connection in the tree of life, but there few body structures look the same and perform the same work. These are the product of convergent evolution.
Convergent evolution is the term that explains how two unrelated species change to adapt to the environment and adapt to the situation. Generally, such species are part of such different environments in different parts of the world that they favour the same adaptations. Therefore, supporting such species to survive according to the changes in that particular environment.
A typical example of analogous structure is the wings of birds, flying insects and bats. These organisms have the common structure as wings and are used for flight, but they have no common ancestors as bats are mammals, which separates them from insects and birds.
In fact, birds are said to be a close relative of dinosaurs, but all three have adapted to the niches of their environment and so evolved such developing wings. Although, this does not show the kind of close evolutionary relationship.
Key differences between homologous and analogous structures
The following points are important in understanding the difference between homologous and analogue structures:
- Such similar structures that are present in related organisms or common ancestors, although different in function, are known as homologous structures. In contrast, such similar structures that are present in unrelated organisms or that do not share a common ancestor but have a similar function are known as analogous structures.
- The wing of a bat or bird, the arm of a human, the wing of a bird, the leg of a dog and the fin of a whale (these are mammals, but the function of the structure is different), are examples of homology. structure, while the wings of insects, bats, birds and fins of fish and penguins are all examples of analogous structures.
- Homologous structures exhibit a anatomy similar, although the difference in the functionsIn the analogous structure there is a difference in anatomy, but similarity in their functions.
- Homologous structures develop in a related species or one that shares common ancestors, while homologous structures develop in unrelated species.
- Homologous structure arises from divergent evolution, and analogous structure arises from convergent evolution.
- Homologous structure evolved due to adaptation to the different environment, while analogous structure evolved due to adaptation to the similar environment of different species.
Conclusion
Homologue and analogue are rather confusing terms in the field of biology, but it is equally important to know them. As this helps to understand the variations and similarities of different organisms, it also helps to build the genetic tree, how organisms evolve and other biological details. So, everyone supports the ‘Theory of Evolution’ in one way or another.