What are Homologous Structures?
Last Updated : 28 Sep, 2022
Evolution is a continuous process of nature. Any species need to upgrade itself. Thus it can able to survive in a continuously changing environment. This change always occurred in a positive direction. This means after the changing of a creature, they became more developed than the previous version. Evolution works in such a way. It takes millions & millions of years to complete a process. Some scientists believe that Evolution is a never-ending process. It g-oes running for an infinite time. During this process, a creature will be always developed. There are many structures developed during the evolution process of certain species. Homologous Structure is one of them.
Homologous Structure
Homologous Structures are those structures, that have the same anatomical structure. But they perform different functions. Homologous Structures are generally a missing link among a set of species. It proves that those species were closely linked up with each other at any point in time. Due to the evolution process, they developed two distinct species. But their origin is the same. Due to some factors, the Homologous Structures developed with the help of natural selection. from the outside of the structure, they can resemble two different structures. As they perform two different functions. But if those structures can be noticed internally, there will be a clear similarity among them. This type of structure developed from a certain evolutionary process, known as Divergent Evolution.
Divergent Evolution
Evolution is a large process. There are many types of evolution. Depending on the structure developed during the evolutionary process & the probability of happening such evolution, scientists divided the evolution into some categories. Divergent Evolution is such a category. In the Divergent Evolution, species will develop from a single ancestor. This means from a single ancestor species, many species can be developed. So, developed species share some common traits among them. Divergent Evolution is the most often evolutionary process that happened in nature. That is the reason behind the available species in nature. Scientists found some common traits between most species. That is why they concluded that Divergent Evolution can be the most important evolutionary process. With the Divergent Evolution, the Homologous Structure developed among the developed species.
Connection between Divergent Evolution & Homologous Structure
Scientists found that the Homologous Structure is closely related to Divergent Evolution. Whenever in nature Divergent Evolution occurred, Homologous Structure developed as a result. As the Divergent Theory states that the developed species must have a common ancestor. So, the developed species will have the same anatomical structure. But due to the natural selection process, they need to develop new traits in it. That is why the structure may perform different functions. Also, for the Divergent Evolution process, they might be looking at the dissimilar from the external.
Vestigial Structures
Vestigial structures are those structures in the body which does not have any particular function and are just the residual part of the ancestors. For Examples pelvic bone of snakes, the human appendix, wings of flightless birds. As they don't have any function in the body but they require extra energy in the body and they can also cause many diseases. Most of them are harmless that's why they are not removed from the body because removing them requires many alterations and can also cause many side effects in the body. These structures are not useless from the start instead they were very useful in ancient times but along with evolution the functions which were performed by these parts no longer exist so they become useless.
Properties of Homologous Structure
- The Homologous Structure can be developed in such species, which were closely related to each other. The species must have a common ancestor in the evolutionary process.
- The Homologous Structures must be similar to the internal. As they will be the same from the anatomical view.
- The Homologous Structure must perform different activities. Then only the structures can be categorized as Homologous Structures.
- The Homologous Structure can be similar to the external. But many times, they don't have a similar view from the outside.
Importance of Homologous Structure
Homologous Structures plays an important role in the evolutionary study. They act as a bridge or as a missing link between two species. Scientists can able to find a clear relationship between two species by studying the Homologous Structures. As it can only be associated with the Divergent Evolution, it can be proof of Divergent Evolution also. Scientists found similarities between two species by finding a relationship between them. This type of discovery helps us to know the process of Evolution. The steps of evolution can also be drawn by studying such structures. That is why Homologous Structure is very important.
Example of Homologous Structure
Structure of Forelimbs of Mammals
The forelimbs of mammals are a very important Homologous Structure. Scientists found a clear relationship by studying the forelimbs. An example can be drawn by taking reference to the forelimbs of Humans, Horse & Bat. The forelimbs can act different functions for different animals. Like the Human use their forelimbs to grab anything. The forelimbs of the Horse are used to run. And the forelimbs of the Bat are used to fly. The functions of the forelimbs are different. But the anatomical structure is the same. All the forelimbs are made with the same set of bones. There are five bones. These are Humerus, Radius, Ulna, Carpal, and Metacarpal. In every forelimb these five bones are present. So, they are the Homologous Structure.
Beak of Birds
Every bird has a beak. The beaks are made with bones. The anatomical structure is the same for all the birds. The same number of bones are required to make a beak of a bird. But they don't perform the same functions all the time. Like the Woodpecker and the Crow have the beak. But the function is not the same. The Woodpeckers use their beak to make a hole in the wood of the trees. From there, they find their food. But the beak of the crow uses to hold many things. The beak of Crow is used for normal purposes. Also, some birds' beak is different from each other. Depending upon the food they usually take, the beak structure pattern changes. So, the beak of birds is also an example of Homologous Structure.
Question 1: What is Convergent Evolution?
Answer:
Convergent Evolution is another type of evolutionary process. Here, two or more species developed from two different ancestors. But they share a common trait between them. It is quite opposite of the divergent evolution. Here, with the help of nature, the same traits developed in two distinct species.
Question 2: What is a Homologous Structure?
Answer:
Homologous structures are those which have the same structures but functions that are different. For example forelimbs of mammals, reptiles, and amphibians, the structure of the forelimbs of these animals is the same but the function of the forelimbs in all these animals is different. These structures originated from similar ancestors.
Question 3: Does the wings of a Bird & Butterfly an example of Homologous Structure?
Answer:
No! The wings of a Bird & Butterfly are not Homologous Structures. As they perform the same function. Also, the anatomical structure of the wings is not the same. So, they are fulfilling the criteria for the analogous structure. That is why they are analogous structures.
Question 4: Does the wings of Bird & Bat an example of Homologous Structure?
Answer:
Yes, The wings of birds & bats are a homologous structures. Though they perform the same function, the anatomical structure of the wings is the same. So, they are fulfilling the criteria for the Homologous Structure. That is why they are homologous structures.
Question 5: Does genetic changes required for developing Homologous Structure?
Answer:
Genetic changes are the basic things in the evolutionary process. When the species tries to get a new trait, it tries to make a change in the gene itself. Natural Selection also helps to make a change there. This genetic change will be inherited by the next generation. Thus, it helps to create new species. The creation of new species from the same ancestor leads to develop a homologous structure.